Anatomy Notes Sem2 2024 PDF

**OVERVIEW OF THE PELVIS** **Learning outcomes** - Discern difference between true pelvis, false pelvis and the perineum - Describe muscles that make up the pelvic diaphragm - Trace the 5 passageways for structures to enter and leave the pelvis - Describe the positional relationship...

**OVERVIEW OF THE PELVIS** **Learning outcomes** - Discern difference between true pelvis, false pelvis and the perineum - Describe muscles that make up the pelvic diaphragm - Trace the 5 passageways for structures to enter and leave the pelvis - Describe the positional relationships between the pelvic viscera - Describe the neurovasculature of the pelvis as it pertains to the reflexes of micturition/defecation - Contrast lymphatic drainage of pelvis and perineum **Bony pelvis -- functions** - Intersection of abdomen and the lower extremity - Locomotor function -- numerous muscle attachment sites and provides an articulation for the lower limb (acetabulum for femur etc) - Integral in weight distribution -- each vertebra is slightly larger than the one above is (inferior = larger) -- sacrum takes all of that bodyweight and distributes it into the lower extremity - Protection of organ -- ilia (superior bony pelvis) -- protects lower abdominal organs ie sigmoid colon - Pelvic bowl protects pelvic organs like rectum, bladder and reproductive organs **Bony pelvis components** Ox coxae -- pelvic bone (fuse at 16-18) -- - ileum (superior bone) with flaring wings (ala) -- the hip = ileum crest - pubis = anterior, articulates with opposite side - ischium -- posterior, when we sit we rest on the ischium Greater and lesser sciatic notches -- important for neurovasc and muscles to leave through - separated by ischial spine - inferior to lesser notch is roughened ischial tuberosity (the origin of the hamstrings) - ischiopubic ramus is a bridge connecting the ischium and pubis -- comprised of inferior pubic ramus and ischial ramus - obturator foramen is a hole inferior to acetabulum -- largely closed by a fibrous membrane, obturator internus and obturator externus  **Posterior -- sacrum and coccyx** - closed by sacrum and coccyx -- sacrum is fusion of 5 inferior vertebrae and distributes weight to ilea, - most inferior aspect of vertebral canal -- final spinal nerves off conus medullaris will travel through holes in sacrum then exit to their targets - coccyx is below sacrum, remnant of 4-5 vestigeal tailbones - most anterior and superior aspect of sacrum = promontory - laterally sacrum will articulate with ilea through auricular surface between each vertebral pair there is an intervertebral foramen, allowing spinal segment to exit the vertebral column -- as the ilea are lateral to sacrum, the intervertebral foramina need to change direction so their exit is not obstructed - anterior and posterior sacral foramina (ventral rami which innervate pelvis and dorsal rami -- spinal nerves outside pelvis) **True vs false pelvis** Pelvis is a general term! - Does it mean cavity or bones?? - Pelvic girdle resides in 2 cavities -- abdominal and pelvic cavity - True pelvis = ring of bones in pelvic cavity proper -- protects pelvic organs like bladder, rectum and reproductive organs - False pelvis -- superior projecting ala -- technically in the abdominal cavity Division between these 2 is the pelvic inlet - Sacral promontory - Arcuate line of ileum - Pectinate line of pubis  No hard borders separating abdomen and pelvis -- pelvic inlert is an IMAGINARY division, just to separate organs between abdomen and pelvis Inferior to pelvis = perineum, separated by the pelvic diaphragm Separated by levator ani **Perineum** - Diamond shaped space, separated from pelvis by muscular pelvic diaphragm Borders - Pubic symphysis - Ischial tuberosity - Tip of coccyx - Separated into 2 triangles -- urogenital anteriorly (pubic symphysis to ischial tuberosities), anal triangle (Ishchial tuberosity to coccyx)  Urogenital triangle - Openings for urinary/repro tracts - External genitalia Anal triangle - Anus (distal GIT tract opening) - Pelvic diaphragm - This space is largely full of fat in real life, separating into 2 fossae **Ligaments of the pelvis** Posterior Sacrospinous and sacrotuberous ligaments Sacrospinous = more medial, between sacrum and ischial spine Sacrotuberous -- descending (more lateral), between sacrum and ischial tuberosities - Anchor distal sacrum to oss coxae - Close off greater/lesser sciatic notches - Anterior, obturator foramen largely blocked by obturator membrane -- also have obtrurator externus outside pelvis and obturator internus within pelvis - Small tunnel -- obturator canal  **Muscles of pelvis (superior view)** Why is it called the pelvic bowl? Most of the floor of our pelvis is made up by the levator ani (cone shaped muscle) - Apex = anal canal (originates on pubis, ileum and the fascia of obturator internus) - Coccygeus -- internal sacrum (anterior) and inserts onto ischial spine -- sacrospinous ligament is just superficial to this! - Piriformis sits within the pelvic bowl  **Inferior aspect** - Obturator internus and piriformis all go onto the femur with their tendons **Muscles of pelvis -- coronal section** Can really see levatore ani tapering down to the anal canal External anal sphincter just deep to the perineal skin **Passageways for structures to enter/leave pelvis** Inguinal ligament goes from the ASIS to the pubic tubercule Under inguinal ligament - Femoral artery, vein and nerve (change their name as they go through thigh) Through inguinal canal - Obliquely running tunnel through the anterior abdominal musculature - Testicular vasculature, vas deferens run through in men on way to testes - Round ligament of uterus will pass through on way to labia majore in women Through obturator canal - Obturator artery, vein and nerve pass through into medial thigh Greater sciatic foramen - Gluteal artery, vein and nerve (pass through on either side of piriformis, superior and inferior on either side) - Pudendal nerve and internal pudendal artery and vein exit through greater sciatic foramen and then turn abruptly to get to perineum Urogenital hiatus - Leaves gap anterior for the openings of urinary and reproductive tracts into urogenital triangle of perineum - Autonomics to external genitalia  **Female pelvic viscera** - Urinary bladder and urethra anteriorly - Uterus and uterus adnexa (ie ovaries, uterine tubes, ligaments etc) - Rectum/anus most posterior **Positional relationships** Between pubis and bladder there is a potential space -- retropubic space, normally filled with loose connective tissue - As bladder is retroperitoneal, the retropubic space is rarely open, can be surgically opened if need be - Between bladder and uterus is real space -- vesicouterine pouch - Uterus and rectum -- rectouterine space -- clinically important as fluids in abdominopelvic cavity will pool into this space - Lay patient supine, put needle into vagina and then through posterior vaginal wall  **The bladder** - Quite textured, compex arrangement of smooth muscle on the wall (detrusor)  Ureters travel underneath the uterine arteries and veins (water under the bridge) They travel to posterior urinary bladder **Urinary bladder** Detrusor muscle is irregularly oriented, makes up wall of bladder and can constrict -- this contrasts the regular longitudinal and circular muscle that exists in the GIT - More efficient for the bladder to expel fluid by collapsing on itself from all directions (not just one or two) -- like how the air can leave a balloon Transitional epithelium lines surface of urinary bladder -- can cope with extreme stretching in storage or evacuation of urine -- apical cells balloon out in an umbrella shape -- as it expands, epithelium stretches and flattens gradually - Upon excretion of urine, the apical cells can once again balloon out as the bladder collapses on itself **Coronal section** - Detrusor muscle makes up most of the organ wall - Urethra opens inferiorly and drains into the vestibule (between the two labia majore, opening for the vagina and the urethra in perineum) - Muscle Becomes more circular as bladder neck approaches and approaches internal urethral sphincter (is this real tho) - Males have much more defined I.U.S, probably mostly for sexual function - External urethral sphincter in both genders is well defined, in childhood we learn to voluntarily contract this muscle until we can find a place to excrete the urine On posterior side we can see two openings for ureters, these, alongside the urethra forms the smooth area known as trigone  Female urethra = 4-6cm in length, 6cm in diameter Anterior to vagina Both of these enter vestibule between labia majora **Paraurethral glands (lesser vestibular), skene's gland** - **Secrete mucus into the lesser vestibule** - Homologous to male prostate - Distal end of the urethra - some antimicrobial functions? - In some females, can create lots of ejaculate fluid like males  **Uterus and adnexa** - Uterus is primary female reproductive organ in pelvis, adnexa is all the additional structures - Fundus superior, body and cervix inferior - Composed of fibromuscular wall called myometrium - Kind of like a sphincter in the cervix to close if off - Endometrium is internal lining, swells to receive fertilised embryo, if this doesn't happen it is shed - Cervix projects into vagina, leaving space on either side known as the fornix - Cervix -- large fibromuscular like sphincter part of uterus, both above and in vagina - Ovary lateral and posterior to the uterus - Superior to ovary = uterine/fallopian tube, with fimbriae (finger projections) which contract to expel eggs from ovaries to the uterus **Ligaments of uterus** Suspensory ligament - Fold of peritoneum form abdominal cavity to ovart - Within it is ovarian artery and vein Ovarian ligament - Anchors ovary to uterine body - Embryological remnant Cardinal ligament - Pelvic floor component - Fibrous connective tissue at base of uterus around cervix - Within it is the uterine artery and vein Uterosacral ligament - Visceral connective tissue condensation, anchoring base of uterus to walls of the pelvis - Ureter comes very close to the base of the uterus and especiallt this ligament - Also from base of uterus Broad ligament - Mesentery of uterus - 3 sections -- mesometrium (metrium = mother, broadest part attached to uterine body), mesosalpinx (trumpet -- uterine tube), mesovarium -- ovary - Mesometrium envelops uterus, mesosalpinx is superior, mesovarium is more posterior  Round ligament - Near ovarian ligament, near fundus of uterus - Extends deep in peritoneum towards the inguinal canal -- embryoloigical structure, heloing anchor uterus to the body wall - Full extent travels all the way to the labia majore **Rectum and anal canal** Characreristic muscle like rest of digestive tract Circular and longitudinal smooth muscle until anal canal - Circular muscle develops into the IAS in the anal canal -- both females and males have feal IAS (not like urinary) -- autonomic control Levator ani -- descends in a cone-like fashion and encircles the anal canal -- ends in the external anal sphincter (skeletal muscle)  **Rectum and anal canal** - Anorectal line -- border between anal canal andf rectum -- 4-5cm distal to anal verge (opening) - Underneath that is the pectinate/dentate line - Rectal epithelium -- mainly simple columnar - Underneath anorectal line -- stratified squamous epithelium (protect from outside wall) - Towards anal verge -- keratinised stratified squamous epithelium (protect the gut tube from the harmful exterior) - IAS runs underneath, EAS skeletal muscle looks different histologically **Male pelvic viscera** - Urinary bladder anterior, rectum posterior - Prostate inferior to bladder, seminal vesicles on posterior wall too  **Positional relaionships** - Males have retropubic potential space between pubic symphysis and bladder - Only one actual space -- rectovesical pouch - Bladder, like in females has irregular detrusor muscle throughout the body, becomes more organised near the internal urethral sphincter (which is real) - EAS is far away from bladder body, distal side of the prostate - Prostate itself -- dense, fibromuscular gland at base of urinary bladder, holding it up - Same trigone as for females  **Urethra (males)** - 18 to 20cm long on average - Normally 3 regions in males - Prostatic (through prostate), membranous (through EUS), spongy/penile (through root and body of penis) -- urethra expands at head of penis into a sinus called navicular (not the bone) and then reaches the world at the external urethral orifice **Prostate and seminal vesicles** - Ureters enter posterior body wall - Vas deferens enters pelvic inlet, travelling along posterior bladder to enter prostate - Seminal vesicles secrete fluid for sexual reproduction (alongside the posterior bladder too) -- and they are hollow with a complex lumen inside - These two lumens converge and open into the ejaculatory duct of the prostate - Bulbourethral (cowper's) glands -- lubricate urethra prior to ejection -- near EUS, into spongy urethra  **Blood supply and venous drainage of the pelvis** - For the most part, veins will accompany the deep arteries (with a few technicalities, multiple veins per artery) - Arteries, generally, are named for where they go -- VERY important to know for pelvis - Lots of variation in the pelvis blood supply, but it's irrelevant so long as the blood actjally goes to everywhere - Cannot be confindent about which artery is which unless you follow it to the actual destination Arterial supply - Mainlky comes from the internal iliac artery (but not always true!!)  **Male schematic -- blood supply through the pelvis** Abdominal aorta, bifurcates before pelvic inlet Right and left common iliac -- we will work off right, assume left is mirrored Between these two, there is a small artery between them, the median sacral Common branches into external (external to pelvis, heads under the inguinal ligament and becomes femoral artery) and internal iliac artery -- posterior and anterior branches [Posterior branches] - Superior gluteal (leaves pelvis) -- medius, minimus and tensor fascia lata, leaves through greater sciatic foramen - Iliolumbar off superior gluteal -- towards sacrum but ascends back to abdominal cavity - Lateral sacral -- inferior on lateral aspect of sacrum [Anterior division] - umbilical (very proximal) -- in adults no longer carries blood to placneta from embryo, but is patent until the anterior abdominal wall where it obliterates (umbilical ligament) - superior vesical (superior part of bladder) comes off the umbilical artery - obturator artery -- goes to obturator canal and enters medial thigh, runs with the nerve - inferior gluteal artery -- goes to gluteus maximus and runs through the greater sciatic foramen - internal pudendal artery -- talk about later but leaves through the greater sciatic foramen - middle rectal -- off the internal pudendal -- superior rectal comes off the inferior mesenteric meanwhile [Male specific reproductive arteries] - inferior vesical -- to the inferior part of bladder, comes off internal iliac between umbilucal and obturator -- this gives rise to seminal vesical arteries and the prostatic artery - artery to vas deferens comes off the superior vesical artery **Female schematic** [Female specific branches] - uterine artery comes off in a similar place to inferior vesical (b/w obturator and umbilical) -- this is highly variable but travels in the cardinal ligament of the uterus - gives off the vaginal artery on its way (upper portion of vagina) - vaginal artery also gives off inferior vesical to the base of the bladder  **Who's leaving the pelvis? (these need to be confidently identified)** - Superior gluteal -- leaves through greater sciatic foramen, superior to piriformis -- travels between the last lumbar and first sacral spinal nerves (ventral rami of the lumbosacral plexus) - Inferior gluteal -- inferior to piriformis, also leaves through greater sciatic foramen -- runs into gluteus maximus, leaves on opposite side of piriformis, inferior to coalescence of lumbosacral plexus - Internal pudendal (these are tough, often these bottom 2 descend as a common trunk) -- but this leaves between coccygeus and piriformis before doubling back into the perineum (enters through LSF after leaving through the GSF) - Obturator - towards obturator internus, leaves out of the obturator canal, travels with the obturator nerve LOTS OF VARIATIONS  **Autonomic innervation of pelvic organs** Sympathetic nerves are thoracolumbar -- between T1 and L2/3 Parasympathetics are craniosacral -- Cn3,7,9,10 or sacral outflow tracts -- S2-4 Pelvic nerves only come from lower lumbar and sacral area - These nerves all coalesce to form the hypogastric plexus for abdomen and pelvis - Superior aspect is mainly sympathetic -- L1-3, synapsing lower down in sympathetic trunk and forming ganglion at superior aspect of pelvic inlet - Inferior aspect has sympathetics synapsing directly in the pelvis and presynaptic parasympathetics from sacral outflow - Once coalescing, they can jump to pelvic organs which they innervate **Somatic innervation to micturition and defacation** Somatic nerve in perineum from S2-4 -\> pudendal nerve Internal pudendal artery leaves the pelvis in GSF, then enters perineum through LSF, the pudendal nerve does the same thing -- innervates several structures in anal and urogenital triangle - Innervates external urethral and external anal sphincters - Micturition and defecation need both smooth (autonomic) and skeletal (somatic) muscles **Micturition reflex** Detrusor and internal urethral sphincter (more regular/circular) are both smnooth muscle Sympathetics store urine urine by relaxing detrusor and contracting internal urethral sphincter As urine levels rise, stretch receptors send signals to CNS that it's time to evacuate, these become urgent as the levels rise to ureteric orifices Median urine in males up to 400mL, body likes to evacuate urine far before capacity Parasympathetics void urine by contracting detrusor and relaxing internal urethral sphincter (open door and force the urine out) - If location is inappropriate, the pudendal nerve will contract the external urethral sphincter until the location is appropriate  **Defecation reflex** Wall of rectum and internal anal sphincter are smooth muscle Sympathetics store feces by relaxing rectum wall and contracting internal anal sphincter Parasympathetics contract wall of rectum and relax internal anal sphincter If location is wrong, pudendal nerve contracts the external anal sphincter until location appropriate **Lymphatics of pelvis and perineum** - Lymph of pelvis different to that of the perineum (typically) - Important for cancer and infection Important nodes - Internal iliac lymph nodes -- internal pelvic structures -- ie internal urethra, cavernous bodies of clitoris and penis, middle part of rectum (as middle rectal artery and vein go to the internal iliac vessels), the prostate, some of the cervix and most of vagina - Inguinal lymph nodes -- external genitalia and perineum -- skin of perineum, anus inferior to pectinate line, rest of penis and clitoris, scrotum and vulva - Preaortic and lumbar nodes -- testes and ovaries, uterine tubes and uterine fundus -- mainly due to embryological origin of gonads and how their vessels drain mainly into IVC not into the internal iliac and aorta  Largely drain structures in pelvis and not perineum (extecpt cavernous bodies of clitoris and penis) Externla iliac lymph nodes -- superior pelvic lymph nodes and near inguinal canal -- seminal vesicles, vas deferens, uterine body and part of the cervix Adult reproductive development ***[LEARNING OUTCOMES]*** - *Orient to the perineum, its subdivisions and fascia* - *Compare erectile tissues of men and women* - *Describe neurovasculature of perineum as it pertains to sexual reproduction* - *Trace reproductive tract of males and females* - *Describe process of sexual differentiation from an early indifferent gonad stage* **Perineum and external genitalia** Perineum is a space inferior to the pelvis, delineated from pelvis by levator ani Perineum = diamond shaped pelvis, bordered by pubic symphysis, tip of coccyx and ischial tuberosities -- urogenital and anal triangles also - Urogenital traigne contains repro and urinal openings, vaginal and external urethral orifices, external genitalia - Anal triangle has distal digestive tract -- anus Levator ani encircles anal canal (cone shaped) -- encircles anal canal at its apex On either side, ischioanal/ischiorectal fossa -- largely filled with fat in real life in both genders Obturator internus is tangential to levator ani (which attaches halfway up on its investing fascia) -- the ischiorectal fossa is hence lateral to levator ani but medial to obturator internus  Anterior in urogenital triangle, inferior to anterior extent of levator ani, we have a thickened membrane -- it goes all the way to the pubis -- perineal membrane -- stable roof for the external genitalia to attach **UG spaces and fascia** -- fascia in perineum is just an extension of abdominal fascia (with different names) Perineal membrane Specific fascia -- superficial perineal (colles), Dartos fascia, deep fascia of penis and perineal body  **Spaces and fascia** Internally we have peritoneum, lining of abdominal cavity, external we have transversalis (endothoracic) fascia -- perineal membrane (composite of lots of tissue) -- transversalis fascia variably contributes to this membrane though - Perineal membrane is also connected to levator ani and the urethral support system More superficially we have Camper's and Scarpa's fascia -- these continue as the Colles' -- superficial perineal fascia - Camper's in males will become the Dartos muscle of the scrotum (smooth muscle) - In females, will make up fleshy subcut tissue of labia majore and mons pubis - Scarpa's will be called Dartos fascia over the penis and will be continue with Colles' fascia in both males and wimen Perineal body is a midline point, fibromuscular, where Colles' fascia, perineal membrane, fascia over levator ani and individual visceral fascia meet together - Midline point between anal and urogenital triangles Colles' and Scarpa fascia also delineate two separate pouches -- the superficial perineal pouch (between Colles' fascia and perineal membrane) Deep perineal pouch is superior to perineal membrane and extends to superior fascia layer (visceral fascia of EUS muscles and levator ani)  Obturator internus lateral to levator ani, colles fasia the bottom straight line in both, perineal membrane at the level of he external sphincter - External genitalia and the openings for urinary/repro tracts are in the superficial perineal pouch - Deep perineal pouch haas anterior extensions of ischiorectal ischiocrectal fossae and deep neurovasculature to the perineum We can follow the path of infections/trauma without the need of imaging by following fascia -- while medical imaging is an amazing tool, we can't send everyone to get a CT -- fascia help us to deduce clinical issues **Clinical correlate** **Extravasion of urine** - Interruption of urethra - Collection of urine within our body spaces/cavities -- could be due to calculus in urethra or a traumatic incident - If the spongy urethra is perforated, urine leaks into the superifical perineal pouch -- urine between Colles fascia and the perineal membrane -- extension of Scarpa fascia and also the dartos fascia - Urine found in root of penis (deep to skin) and also in the scrotum -- also expect to see it between the rectus sheath and superficial fasic over the abdomen If the wound was more proximal, urine would not be able to escape the perineal membrane, so we'd have urine between peritoneum and transversalis fascia and in ischorectal/ischioanal fossa **External genitalia** Mons pubis -- rounded fatty eminence anterior to pubic bone, the amount of fartty tissue varies throughout life - Highest at puberty, lower at menopause Labia majora -- prominent folds protecting labia minora and structures in vestibule Labia minora -- fat-free folds of hairless skin, core of spongy erectile tissue and anterior form the frenulum and preface foreskin of clitoris Clitoris -- erectile organ -- 4-7mm in length, 1cm in diameter Internal extent of clitoris can be 4-7cm in length Vestibule -- space outlined by labia minora, within it is the external urethral orifice and the vaginal orifice Posterior to this is the external anal orifice/anal verge  Deep to the skin, erectile tissue is more complicated Clitoris has multiple tissues -- crus for example - Right and left crura are cavernous erectile tissues anchored to the ischiopubic rami -- these two meet in the midline to form the body of the clitoris - Glans clitoris is what is visible at labia minora junction (spongy erectile tissue, highly sensitive nerve endings) - Deep to labia are the bulbs of vestibule -- 3cm long spongy erectile tissue, limiting the opening of the vagina - Posterior to vestibule are the greater vestibular glands -- secrete lubricating fluids in sex into vestibule and distal vagina **Spongy vs cavernous erectile tissues** In general, erectile tissues are where deep arteries/veins can open up into sinuses Normally closed but during sex these relax to let blood into these tissues Spongy - Less blood during erection - Ideal for patency -- located near structures that have a lumen or need to remain open - Does this through having a thin connective tissue covered Cavernous - Hold more blood - Good for turgidity and rigidity - Found in areas where erection needs to be near blood pressure -- thick and taut connective tissue covering known as tunica albuginea - Most of the clitoris and crura are cavernous -- clitoris needs to be turgid in erection, needs to be supported by equally turgid crus - Bulb of vestibule and the glans clitoris are spongy though As bulb is on both sides of vaginal orifice, the aim is to keep vaginal orifice patent but limit the size **Skeletal muscles** Erectile tissues covered in skeletal muscles Crus of clitoris overlayed by ischiocavernosis Bulb of vestibule overlied by bulbospongiosis Many functions -- main one is to maintain erection - Reflex arc where stretch receptors are triggered due to erectile tissue becoming engorged with blood -- muscles contract to pinch off veins which normnally drain these tissues - Muscles aid in erection and in maintaining erection [Superficial/deep transverse perineal muscles ] - Support pelvic floor - Support abdominopelvic viscera - Maintain intra-abdominal pressure  **External male genitalia** Externally, body of penis and glans penis -- full penis not visible externally -- root of penis (anchor to the ischiopubic rami) also can be similar in length to external penis Spermatic cord goes into the testis -- in it is the vas deferens and testicular neurovasculature testis sit in scrotum - fibromuscular sac, and is the home of spermatogenesis epididymis arcs over testis and receives newly developed sperm, storing it till it becomes mobile **Testis** - Produce testosterone and sperm - Surface of each covered by tunica albuginea - Fibrous septa extend internally between lobes of tightly coiled seminiferous tubules - Seminiferous tubules = sperm production, join with straight tubules (rete testis) in mediastinum of testis -- where neurovasculature enters - Sperm goes into the efferent tubules and then the epididymis (3 regions -- head, body and tail) -- tightly coiled tube appearing like a solid mass - Continuous with vas deferens which transports mature sperm to pelvic cavity  **Male erectile tissue** Penis similar to clitoris Root of penis consists of the 2 penis crura -- meet in the midline to form the corpus cavernosus (cavernous body) Also contains the bulb of the penis (unlike female vestibules on both side) -- as males don't have vestibules and because the urethra joins the penis, the bulb becomes one structure - Tapers as it enters penis as the corpos spongiosum - Greatly expands to form the glans penis distally Glans penis contains external urethral orifice, arches over the distal corpus cavernosym Just like the clitoris, most of the penis is cavernous (for turgidity, erection, anchoring to ischopubic ramus), corpus spongiosum is however spongy, urethra needs to be patent in sexual reproduction **Perineal muscles -- male** Bulbospongiosus over bulb of the penis Ischiocavernosus over crus of the penis - Both aid in sustaining erections, also void urine/semen from the distal urethra Also have superficial and deep transverse perineal muscles  **Neurovasculature** Internal pudednal leaves through greater sciatic foramen In the following images, levator ani has been cut -- obturator internus on both sides of it, coccygeus posterior (between sacrum and ischial spine) Piriformis just superficial to lumbosacral plexus External anal sphincter off the levator ani Internal pudendal artery exits pelvis through greater sciatic foramen, turns towards perineum, running over sacrospinous ligament (next to coccygeus) and under sacrotuberous ligament (through the lesser sciatic foramen) - Runs through the investing fascia over obturator internus to access the perineum Coccygeus is really small and runs just superficial to coccygeus After internal pudendal passes over sacrospinous ligament, enters greater sciatic foramen Runs under sacrotuberous ligament to go through lesser sciatic foramen Passes through obturator internus investing fascia -- runs through pudendal/alcock's canal GSF superior to sacrospinous ligament Outside levator ani cone we have the ischiorectal fossa, and the internal pudendal artery runs on the very lateral side of that, just on medial side of obturator internus - Gives off lots of branches from Alcock's canal  **Branches** First few, medial to anus, EAS and ischioanal fat - inferior rectal artery Gives off perineal artery, bifurcating on either side of the superficial transverse perineal muscle -- the superficial and deep perineal supply muscles of external genitalia and erectile tissues Dorsal genital artery -- to dorsal clitoris and penis -- deep to perineal membrane, coarses along crura and emerges on dorsal aspect of the genitalia A diagram of the muscles of the pelvis Description automatically generated **Perineal nervous innervation** Perineal nerve follows same path as the internal pudendal artery, gives off similar named artery Somatic nerves for skeletal muscles -- does not control erection but innervates bulbospongiosis and ischiocavernosis and MAINTAINS erection -- does NOT initiate it Innervates external anal and urinary sphincters also  **Autonomic innervation of erectile tisse** Comes from inside pelvis -- hypogastric plexus Autonomics enter urogenital triangle through urogenital hiatus after innervating pelvic organs A diagram of the human body Description automatically generated Sexual reproduction is complex interplay between somatic pudendal nerve and these autonomic nerves Parasympathetic -- erection/remission (after ejaculation/orgasm) Sympathetic -- emission/ejaculation (before and during ejaculation/orgasm) Somatic -- maintain erection/aid in ejaculation -- by innervating bulbospongiosis and ischiocavernosus, aid in male ejaculation/female lubrication by pressing on the greater vestibular gland and also aids in orgasm **Female reproductive tract** Ovaries are oval shaped female gonads which contain oocytes and also produce hormones Suspended by ovarian and suspensory ligament and wrapped around by broad ligament Once a month, one ovary will expel one oocyte into the peritoneal cavity - Oocyte trapped by finger-like projections over medial aspect of ovary which pull and guide oocyte into uterine tube - 4 sections, infundibulum (funnel shaped, opens into peritoneal cavity, has fimbriae) - Ampulla -- widest and longest where fertilisation of oocyte typically takes place - Isthmus -- narrows uterine tube and has a thick muscular wall, entering into horm of uterus - Intermural part -- short segment into myometrium and enters uterus through uterine osteum  Hormones trigger endometrium changes, with it becoming swollen and highly vascularised A few days after oocyte expulsion, production of homrones like progesterone diminishes Without fertilisation and impkantation of an embryo to compensate, the endometrium also diminishes -- goes ftom 6 to 1 mm in thickness - Blood from surface vessels escapes causing a haematoma, and the endometrium and blood supplying this layer eventually become completely shed **Erectile tissues and sexual stimulation** - Smooth muscle in the crura relax and allow blood to dilate the cavernous sinuses (this is through parasympathetic innervation) -- in erection - As these are cavernous, the blood within these regions are close to blood pressure -- very rigid - Bulbospongiosis and ischiocavernosus go trough a reflex arc to compress the veins (somatic innervation) -- when they feel the erectile tissues are being engorged with blood, a reflex arc contracts these muscles through pudendal nerve to cut off the venous drainage of this area **Greater vestibular glands** - Secrete mucus during sexual arousal to lubricate vestibule - Overlayed with bukbospongiosus - Homologue to male bulbourethral glands (also lubricating) **Vagina and cervix** - Vagina underrg0oes distension during intercourse and childbirth - Vagina extends from 7-9cm long - Acidic environment in vagina poses an obstacle to approaching sperm - Cervical os opens during puberty and is exposed to the acidic environment of vagina, this further opens in reproduction to let sperm enter cervix **Ejaculation/orgasm** - Is this real in women? - Proponents believe Skene's glands (periurethral -- similar to prostate) -- can secrete lots of fluid during an organism -- but in orgasm bulbospongiosus and ischiocavernosus contract violently due to pudendal nerve **Remission** - Involves PNS, SNS and somatic control - Smooth muscle constricts arteries supplying cavernous tissue, decreasing arterial flow, bulbospongiosus and ischiocavernosus relax to let blood out **Reproduction** - If sperm go through the acidic environment of vagina, through cervical oss - Choose correct uterine tube to enter and make it through oocyte cell membrane, cell fertilisation will occur  If this happens and embryo implants successfully, embryo prolongs progesterone production in the ovary till the placenta can take over This sustained progesterone prevents menstruation (gravid phase) **Ectopic pregnancy** Successful implantation should happen within the uterine cavity, but sometimes the egg can implant in any place causing an ectopic pregnancy -- ie on ovary surface, in uterine tube and in peritoneal cavity -- ectopic pregnancies will abort themselves normally due to a lack of nutients, but if they don't then it is dangerous  **Pregnancy** - Uterus enlarges and pushes other orfgans out of the way - Respiratory diaphragm stays at the same height, the rest of the abdominal organs have to fit in leftover space - Cervix becomes rigid, then shortens and softens before birth - Cervical and thoracic spine straighten, lumbar spine becomes more lordosed - Normally cervical lordosis, thoracic kyphosis, lumbar lordosis, kyphosis sacrum - this is to maintain center of gravity between legs - In pregnancy, center of gravity moves more anterior -- we compensate by straightening the cervical and thoracic spine and allow lumbar spine to become even more lordosed - Pubic symphysis and sacroiliac joints relax -- this affects locomotor gait **Male reproductive tract** **Erectile tissues/sexual stimulation** - Smooth muscle relaxes near arteries near corpora cavernosa and crura of penis allowing blood to flow in and dilate cavernous spaces (parasympathetic) - Bulbospongiosus and ischiocavernosus do the same reflex arc as in females -- contract to compress venous return from erectile tissues **Testis and epididymis** Sperm develop in seminiferous tubules Move into epididymis to gain motility, "learn how to swim" -- as they come through rete testis and efferent tubules **Vas deferens and seminal vesicles during emission** Sperm moves from epidiymis to the prostatic urethra throughsmooth muscle contractions -- sympathetic innervation Seminal vesicles - Fructose (energy for sperm) - Prostaglandins (dilates cervix) - Bicarbonate -- neutralise the acidic vagina **Prostate** - As sperm and seminal fluids move through ejaculatory duct, sympathetics innervate prostate Produces: - Citric acid (nutrient for sperm health) - Seminalplasmin (antibiotic) - Prostate specific antigen -- liquifies semen **Bulbourethral glands** - Sympathetic innervation - Clear mucus secretion (lubricant) to condition urethra before ejaculation **Ejaculation** - Smooth muscular contractions continue from emission (sympathetic) -- violent! - Internal urethral sphincter closes (sympathetic) -- important to prevent sperm/seminal fluids from entering urinary bladder -- hence why IUS is more important for reproduction - Bulbospongiosus and ischiocavernosus contract to expel semen forcefully **Remission** - Smooth muscle (sympathetic) constricts cavernous tissue, cutting off most arterial flow - Bulbospongiosus and ischiocavernosus relax to open up veins **Embryology** **Urinary embryology** "urogenital system" -- both derived from common mesodermal ridge -- intermediate mesoderm, excretory ducts of both enter a common cavity: cloaca Reproductive system co-opts a developing kidney as the definitive kidney develops in the pelvis  **Development of urinary system** - 4^th^ week -- primary excretory duct -- mesonephric duct (wolffian duct once co-opted by reproductive system) -- starts in cervical region - Grows caudally and gives rise to 3 nephric structures - Pronephros -- cervical region, degenerates - Mesonephros -- thoracolumbar region -- functional for 4-6 weeks, atrophy and degenerates in females (forms part of genital system in males) -- not fully true as some remnants remain in adult female anatomy as cysts near the ovaries -- mesonephros and nephric structures largely degernate in females and have no true function in women - Metanephros -- lumbosacral region from local condensation of mesenchyme (metanephric blastema) and outpocketing of mesonephric duct called ureteric bud **Development of reproductive system** **3 levels of sexual development** Genotype -- females vs males (XX vx XY) -- determination occurs at fertilisation which directs gonadal development which in turn directs phenotypic development of reproductive tract and external genitalia Gonadal -- ovaries vs testis Phenotype -- vagina vs phallus (secondary sexual characteristics) Sex in biology assigned based on above levels -- they can technically be discordant in terms of gonads vs phenotype -- and also some bs about gender **Indifferent gonad** Around 5^th^ week, gonad appears as cellular proliferation on medial aspect of mesonephros -- the genital ridge -- gonad has no sexually differentiating features till about week 7 **Primordial germ cells** - Form early in development from epiblast - Far from somatic cells until week 5 - Necessary for development of gonad - Housed in yolk sac, migrate to area adjacent to developing mesonephric kidney  A diagram of a human body Description automatically generated Little dots in second image are primordial germ cells moving towards embryo from yolk sac Migration through dorsal mesentery and into medial surface of mesonephros triggers development of this genital ridge -- coelomic epithelium thickens, proliferates and forms the genital ridges - This induces differentiation of primitive sex cords once they are at the ridges  Migration of these germ cells chooses which duct to prolong Mesonephric duct -- wolffian duct, paramesonephric duct = mullerian duct (parallel to mesonephric) -- we only can keep one duct when developing into adult Mesonephric duct persists in male anatomy, paramesonephric duct remains in females (some remnants left behind, but they are mostly useless) **Male development** Genetic males (X, Y) carry the SRY (testis-determining gene) -- this sits on the Y chromosome - Creates the SRY protein, differentiating somatic support cells in this area into sertoli cells - Sertoli cells and interstitial cells form the testis cords Mesonephric duct contains the mesonephric tubules still -- gonadal ridge on mesonephros persists and the sertolin cells there form testis cords -- these then get organised into rete testis (in testicular mediastinum) -- this entire thing gets surrounded by tunica albugenia -- coelomic epithelium separated from testis cord A diagram of a human body Description automatically generated **Male development** Sertoli cells make anti-mullerian hormones which actively degenerates mullerian duct The mesonephric ducts remain and connect testis to prostatic region  Sertoli cells also recruit mesenchymal cells to reidges that differentiate into Leydig cells -- to produce testosterone and hence produce secondary sexual characteristics Testosterone Fetal life - Differentiate epididymis, vas deferens, seminal vesicles and "male brain" Puberty - Canalise seminiferous tubukles, spermatogenesis, secondary sexual characteristics (muscle growth, body hair, deeper voice) 5-alpha reductase protein transforms testosterone into dihydrotestosterone Fetal life - Differentiate indifferent external genitalia into penis and scrotum, prostate, male urethra Blue -- dihydrotestosterone Brown -- testosterone **Female development** X,X and no SRY protein Somatic support cells of gonad differentiate into follicle cells (not sertoli) - Mullerian duct persists (no AMH) -- differentiate into uterine tubes, uterus and upper vagina - Mesonephric ducts degenerate in the absence of Leydig cells - Epoophoron and paroophoron remnants of mesonephros  **How to remember this?** Mesonephric was connected to the kidney as part of primitive glomeruli -- the relationship between this and the kidney continues -- attached to the gonad via tubuoles (ie testis attached via vas deferens and epidiymis) Paramesonephric duct never attached to actual gonads (just parallel) -- ovary not attached to tube, instead needing to expel oocyte into peritoneal cavity and be taken up by contraction of fimbriae **Female development** - Tip of mullerian ducts fuse at the caudal end to the urogenital sinus (anterior cloaca) - This induces formation of sinovaginal bulb - They begin to fuse cranially forming the uterovaginal canal (eventual uterus) - Unfused cranial portions become the uterine tubes - Septum dividing the two ducts eventually degrades, forming a common intrauterine space - Sinovaginal bulb proliferates and elongates eventually forming a lumen connecting openings of paramesonephric ducts (uterus) with the urogenital sinus - Upper 1/3 of vagina -- paramesonephric ducts - Lower 2/3 -- endoderm derivative from the urogenital sinus This fusion starts at about 9 weeks, keeps developing until birth These two tubes may not fuse correctly! **Clinical correlates**  Failure to fuse in upper margins -- divided uterus If the paramesonephric duct fuses to urogenital sinus separately -- two separate sinovaginal bulbs with their own uterus -- double/didelphic uterus A diagram of a human embryo Description automatically generated  **Indifferent state table** A table with text on it Description automatically generated **Differentiation of external genitalia** Early development similar in both sexes Genital tubercule anteriorly and midline and cloacal folds more laterally and posterior Cloacal folds become urogenital folds along urogenital sinus and anal folds along anal sinus and there are also labioscrotal swellings lateral to this  **Formation of external genitalia** - Genital tubercule forms as underlying proliferation of mesenchyme covered with ectoderm - Mesoderm around anal membrane = anal folds - Urogenital folds around urethral plate, labiosacral fold lateral to them - Folds continue to grow, depending also on if the embryo becomes male or female **Male external genitalia** - Urethral plate excavates into genital tubercule - Acquires a urethral groove - Invagination continues and gets closed by urethral fold swelling -- "zipping" distally rowards glans penis enclosing the penile urethra - Labioscrotal swelling fuse in midline to form scrotum A diagram of the human body Description automatically generated **Clinical correlates** - Ideally, the only urethral opening should be distal in glans penis - Hypospadias -- abnormal ventral openings on the ventral (underside) of the penis -- failure of the urogenital folds to fuse normally -- can be penoscrotal (when lavioscrotal swellings and urethral folds fail to fuse, penile, in glans or coronal - Epispadias -- urethral openings on dorsal aspect of penis (more related to abdo wall defects) **Female genitalia** - No androgens to direct female genital tubercule growth - Instead the labioscrotal swellings become labia majora, urethral folds do not fuse across midline forming labia majora and genital tubercule bend inferiorly to form clitoris  **Descend of the gonads -- male** Embryological ligament from labioscrotal swelling to gonad -- gubernaculum -- runs through inguinal canal to enter abdomen from gonad Guides each gonad into place -- gubernaculum shortens in males, extra-inguinal portion (bit outside body wall) -- shortens and pulls testis down into pelvis until 3-4 month in utero, through more shortening, they are pulled through inguinal ring into scrotum, bringing the anterior abdominal wall layers woth it - Some of the peritoneum (processus vaginalis) -- outpockets through inguinal canal as well -- causing a connection between abdominopelvic cavity and developing scortum within first postnatal year  Within first postnadal year -- this section of peritoneum is obliterated, leaving a remnant only, the tunica vaginalis on the ventral surface of the testis - Without this obliteration, wre get a congenital indirect ingional hernia -- where connection between scortum and abdomen maintained, accumulation of fluid or loop of bowel in scrotum -- can cause a testicular hydrocele (serous fluid draining into testis and can't be drained away) - Testis may also not descend correctly -- incorrect gubernaculum shortening -- so we can get inguinal, abdominal or prepubic -- cryptorchidism **Descent of gonads -- female** - Gubernaculum does not shorten -- but causes ovaries (through rest of body elongation) to descent in the 3rd month in utero - Allows the testis to move laterally into peritoneal fold of the uterus - the broad ligament! - Embeds itself into mesovarium, gubernaculum becomes 2 structured (originally goes from gonad, through ligament to labia majora) -- with developing labia majora and uterus, the guvernaculum gets adhered to developing uterus and becomes 2 structures -- round ligament (anchors to the body wall via its path through inguinal canal) and ovarian ligament -- anchoring ovary to uterus A diagram of the reproductive system Description automatically generated **Differences in sex development -- discordance** **Androgen insensitivity syndrome** - Phenotypically normal looking female -- with 46XY genotype and undescending tesdtes - Female external genitalia, vagina ends in blind pouch, uterus and uterine tubes absent  - Insensitive to androgens like testosterone -- if one is insensitive, even if testosterone is produced, the AMH degenerates the mullerian ducts, but we also don't get testosterone or dihydrotestosterone formation of the male genitalia **5a reductase deficiency** Individuals have male gonads and 46XY chromosome, female phenotype Testosterone cannot be converted to dihydrotestosterone -- male gonads can't develop Testosterone acts at puberty as well to develop male secondary sexual characteristics -- hence no male external genitalia, only normal internal genitalia - External gneitalia, intead of going down male line to form the expanded genital tubercule, those folds remain open and develop into labia and the penis becomes a clitoris? - At puberty -- increased muscle mass, changes in voice and body hair - Genetic male with feminised genitalia **Virilising congenital adrenal hyperplasia** - Disorder of fetal adrenal glands with excessive androgen production - Everything normal, but too many androgens causes external genitalia to develop along male line (hence we get penis, prostate, scrotum -- albeit smaller than usual) Anatomy of the labia and clitoris ***[LEARNING OUTCOMES]*** - *Define the vulva* - *Describe structure, function and neurovascular supply of the labia minora and majora* - *Understand the range of normal anatomical variation in the appearance of the labia* - *Describe structure, function and neurovascular supply of the clitoris* - *Compare and contrast development of the labia and clitoris with development of penis and scrotum* **Why this topic?** - Underrepresentation within anatomical and gynaecological texts -- ie Last's anatomy - New editions of texts attempt to address inequity - Evidence for a disconnect between societal ideals and anatomical reality - Increasing cosmetic surgery on labia due to a lack of knowledge amongst students **Key terms** Vulva -- region consisting of mons pubis, labia majora, labia minora, vagina (vestibule and orifice) and vestibular glands Other tempers = pudendum (being removed -- as it means to be ashamed) and external genitalia Vagina is NOT the vulva (rest of vagina superior to vulva, inferior to uterus) **Key structures** **Mons pubis** - Rounded area of hair bearing skin and adipose tissue anterior to pubic symphysis, pubic tubercules and superior pubic ramus - Hairless and flat before puberty, more fat after puberty, less after menopause **Labia majora** - Bilateral, prominent folds of skin going from mons pubis anteriorly to perineum posteriorly - Lateral boundaries of vulva **Labia minora** - Between labia majora - Two cutaneous folds of skin, free of fat and hair **Clitoris** - Seen anteriorly (although only the glans can be seen externally) **Vestibule of vagina** - Between labia minora - Means entrance chamber (hence contains vaginal orifice, external urethral orifice and greater vestibular glands) - Greater vestibular glands = bartholin's glans -- analogue to bulbourethral glans in men (about ½ com in diameter, open into vaginal vestibule and secrete mucus fluid in sexual arousal Anus not part of vulva **Hymen** - Thin fold within vaginal orifice of mucus membrane - Border between vestibule of vagina and actual vabina - Variable/misunderstood bit of anatomy Shape could be - annular (ring like) - cresenteric/semilunar -- widest posteriorly - fibriated/denticular - septate - cribriform  no established function elastic fibres -- if penetrated it can stretch or could be torn **External labia majora** Photo taken in lithotomy position -- limbs abducted Labia majora joins anteriorly to form anterior commissure of labia majora below pons pubis Extend posteroinferorly and merge to form the posterior commissure of labia majora (overlies perineal body) -- posterormost limit of labia Anterior parts typically thicker than posterior - laterally, labia majora form border with thigh -- genitofemoral sulcus - medially, they border labia minora -- with thighs adducted, this forms pudendal cleft Following puberty, labia majora are covered with coarse hair - skin more pigmented than the surrounding thighs - labia minora smooth and hairless, with large sebaceous follicles **Subcutaneous** Deep to skin -- loose connective and adipose tissue intermixed with smooth muscle (like dartos muscle of scrotum) Similar to anterior abdominal wall -- superficial fatty layer, deep membranous layer (Colles' fascia) Highly vascular region, many vessels visible Round ligament terminates in adipose tissue/skin of the anterior labia majora  **Labia minora** - one is called labia minus - cutaneous folds without hair of fat - internal to labia majora, enclosed within pudendal cleft -- narrow cleft when thighs adducted - typically moisture keeps labia minora passively opposed, hence vaginal vestibule also closed - anterior labia minora split to form two laminae (layers) - medial laminae unit to form frenulum of clitoris - lateral laminae unite to form prepuce (hood) of the clitoris - posteriorly connected by the frenulum of labia minora (fourchette) - labia minora have many sebaceous glands, lots of nerve endings, core of spongy connective tissue with erectile tissue at their base (lots of blood vessels too) overall, labia majora and minora help to protect vaginal and urethral openings, direct urine and contribute sensory/erectile tissue for sexual arousal and intercourse **Neurovascular supply** Lots of sources! **Arterial supply** Anterior labial branches of the external pudendal artery (from femoral artery) -- supplies anterior labia Posterior labial branches of internal pudendal artery (from internal iliac artery) -- supplies posterior labia - anastomose for eac other, provide vascular engorgement during sexual arousal **Venous** - venous drainage via tributaries of the internal pudendal veins lymph -- drains to the superficial inguial nodes, anterior portions drain to deep inguinal nodes **Innervation** Anterior parts -- anrterior labial merves -- ilioinguinal nerve (L1) -- anterior 1/3 Posterior 2/3 -- posterior labial nerves -- pudendal nerve -- S3 Hence there is an internervous line of non-overlap, neighbouring parts of the labia are supplied by dermatomes of nonconsecutive spinal cord segments - in nerve blocks, pudendal and ilioinguinal blocks might both be required all students identify no labia minora or pubic hair visible as being normal  **Normal variation of the labia** Very little research until recent -- Lloyd et al frirst stydy **Diversity** - lots of size, colour and rigidity variation - 20-100mm length range, 7-50mm width range - 10 studies published now 5-100mm length and 1-60mm width range Labia minora wider pre-menopause Labia minora produding beyond labia majora more common than not Asymmetry between left and right is common Etymology of word clitoris is debated, but potentially comes from the Greek word to rub -- kinda correct as its only function is for sexual arousal Shoutout Helen O'Connell -- best clitoral researcher in the world (work done recently!) **Clitoris** Erectile structure The public thinks of it as only the section which can be viewed externally (only the glans) -- majority of clitoris is more deep, broad attachments to surrounding structures - Glans is midline, densely neural (only externally visible part of clitoris -- continuous with most caudal part of clitoris body - Glans covered by the prepuse (hood of clitoris) -- lateral lamina of labia minora - Also connected via the frenulum of clitoris (medial lamina of labia minora) Clitoris deep to mons and labia Glans forms tip of clitoris body (angled structure, projecting into mons pubis fat) -- can sometimes be palpated through skin as is superficial - Body continuous with crura of clitoris, connected to ischopubic rami and perineal membrane) - Bulb of clitoris lie on either side of the vestibule of vagina (sometimes described as bulb of the vestibule but they ARE separate to the vestibule) - Greater vestibular glands in contact posteriorly with the bulbs of the clitoris Crura and bulbs sometimes called root of clitoris  **Erectile tissue of clitoris** 2 pairs of erectile tissues forming clitoris -- corpora cavernosa (forming crura laterally and form body) -- separated by an incomplete fibrous septum Bulbs of clitoris comprised of spongy erectile tissue, homologous to corpus spongiosum of penis **Muscles related to clitoris** Clitoris in superficial pouch -- between deep fascia, perineal membrane and superficial perineal fascia -- some muscles here (also contains erectile tissues, 3 superficial muscles and the greater vestibular glands (NOT bulbourethral tho) Crura covered by ischiocavernosus muscles Bulbs covered by bulbospongiosus (same structures exist in penis too) Suspensory ligament of clitoris -- attaches it superiorly to the pubic symphysis  **3D view of clitoris** -- multiplanar structrure Broad attachment of crura on ischiopubic rami and the bulbs to the perineal membrane Sharp angle where proximal body attaches to the pubic symphysis -- the angle of the clitoris Bulbs surround the external urethral and vaginal orifices partially Section based studies may be biased by lack of blood flow, embalming studies and the fact most donors are also post-menopausal  **Relation of clitoris to urethra and vagina** Clitoris bright white on MRI Triangular clitoro-uretrhral vaginal complex -- but the clitoris is not functionally related to urethra unlike the penis - These three come together in the putative erogenous zone (G spot) **Neurovascular supply of the clitoris** Neurovascular bundles ascend along periosteum of ischiopubic rami Arteries -- internal pudendal artery -- - dorsal arteries traverse suspensory ligament and run along dorsal aspect of clitoris to the glans - terminal branches of the internal pudendal - deep arteries are hte other terminal branches -- supply corpora cavernosa - internal pudendal also gives off artery of bulb veins -- dorsal vein for drainage, drains into vesical venous plexus lymphatic drainage to deep inguinal nodes nerves - pudendal nerve -- sensation via the dorsal nerve of clitoris - glans is more innervated than rest of clitoris, has less erectile tissue (more important in sensation) - parasympathetic fibres from the cavernous nerves of uterovaginal plexus -- reach via arteries supplying clitoral erectile tissue and help cause vascular engorgement of the clitoris  **Erection reflex arc and orgasm** Only responsible for sexual arousal and pleasure Engorgement of corpora causes clitoral erection Engorgement of bulbs causes vulval swelling -- helps support vaignal orifice and prevent micro-organism movement into bladder during sex Reflex arc 1. receptors on clitoris and vulval skin -- stimulation occurs directly or indirectly through other structures like distal vagina 2. afferents travel through pudendal nerve to reach the central nervous system (esp spinal cord segments S2-4) 3. visceral efferents via cavrrtnous nerves reach receptors on clitoral erectile tissues 4. causes dilation of arterioles supplying the erectile tissue and vascular engorgement 5. sufficient arousal causes orgasm -- sympathetically mediated through T12-L1 through hypogastric nerves and inferior hypogastric plexus to uterovaginal plexus 6. causes reflex muscle contraction -- smooth uterus muscle and skeletal in perineum through pudendal nerves **Development of labia and clitoris** Up to week 7, external genitalia are undifferentiated -- we don;'t know if we'll get penis or labia - have genital tubercule, urogenital folds and labioscrotal swelligns more laterally - structures which well develop are still indeterminate at week 10 -- but urogenital folds will be separate - genital tubercule will elongate to form primordial phallus but stays small and neither genital nor labioscrotal folds will fuse - primordial phallus bends inferiorly to form glans of clitoris - urogenital folds form labia minora - labioscrotal swellings form labia majora - paired labia lateral to vaginal vestibule -- protect external urethral orifice and vaginal orifice  **Comparing labia and clitoris to penis and scrotum** When penis and scrotum develop (due to androgens) Urethral groove forms on ventral aspect of urogenital plate, genital folds on either side - as the genital tubule grows, urogenital folds fuse and grow in midline, beginning in perineal region and progressing distally towards glans penis - converts urethral groove into enclosed penile urethra - labioscrotal swellings fuse in midline to form scrotum - genital tuberucule grows to form glans penis and penile shaft **Analogous structures** - differences due to fusing (creating penis and scrotum) or remaining separate (to form labia) intersex conditions can cause a variety of external genitalia appearances (abnormalities of genital development)  Labioscrotal is named after what it forms! IMAGING WEEK 1 **Quiz 1** X-ray density list -\> metal (white), bone, fluid/fat/soft tissue, air A -- sacrum (wider than I thought) B -- sacroiliac joints C -- coccyx D -- ileum E -- iliac crest (the actual top of the ileum) F -- ischium (ischium has that weird downwards curve) G -- pubis -- closer to symphysis H -- pubic symphysis I -- obturator foramen J -- acetabilim K -- ASIS L -- AIIS (these two are close together, both lateral side!) M -- ischial spine -- medial version of the AIIS, highest point of ischium **Male vs female pelvis** - smaller pubic arch angle - narrower pelvic inlet - smaller bispinous diameter - superiorly elongated ilia **Osteoarthritis features** - osteophytes - subchondral cysts/sclerosis - joint erosion/space narrowing Pubic symphysis separation compromises pelvic stability, the ability of the person to weight-bear, this can be due to shear forces or traction forces **Pelvic inlet order** - sacral promontory - sacral ala (wide area) - arcuate line on ileum - pectinate line of pubic ramus (superior) - pubic symphysis **Outlet** - coccyx tip - sacrotuberous ligament - ischial tuberoisties (bony prominence opposite to ischial crest) -- most inferior and posterior margin of the bony pelvis - pubic arch the larget the gluteal muscle, the more posterior it is! Hence maximus furthest away from the ileal wing ischal tuberosities and femur are all that can be seen at the inferior pelvic margin ischial spine is the most posterior component of the ischium, seoperates the greater and lesser sciatic notches, lateral to the acetabulum Pubic bone the most anterior part of the bony pelvis, can see as anterior to coccyx on the sagittal CT  LATERAL (not sagittal) view 1. lumbar vertebrae 2. sacrum 3. PSIS 4. ASIS (above iliac fossa and iliacus muscle!) 5. Iliaqc crest 6. Coccyx 7. Acetabulum **Quiz 4** Urethra anterior to the vaginal canal, anterior to vaginal canal Rectouterine pouch -- pouch of douglas! -- where fluid amasses in women (can see on ultrasound) Longitudinal ultrasound is not symmetrical, transverse is  A - Rectus abdominus (I think this transverse view foes front-back) B -- bladder (posterior to RA) -- no echo C -- vaginal canal -- posterior to bladder, collapsed potential space D -- thick muscular wall E -- uterus, long lumen, closer to superior nladder aspect (how we know its superior?) **Quiz 5** **Viscera and their arteries** Uterus -- uterine artery -- anterior division of internal iliac **Bladder** Superior vesical -- umbilical artery Inferior vesical -- anterior division of internal iliac artery **Rectum** Superior rectal artery -- inferior mesenteric artery Middle rectal -- anterior internal iliac artery Inferior rectal -- internal pudendal artery **Glutes** Superior gluteal artery -- posterior division of internal iliac Inferior gluteal -- anterior division of internal iliac Abdominal aorta branches into common iliac arteries at level of L4 -- these branch into the internal iliac (posterior) and external iliac (anterior becomes femoral after going under inguinal ligament) Umbilical curves around, superior vesical to middle of obturator foramen  A -- abdominal aorta B -- common iliac C -- internal iliac D -- external iliac E -- femoral head F -- pubic symphysis G -- femoral artery H -- lumbar vertebrae I -- bladder Internal pudendal goes back through the LSF and alcock's canal to run more anterior, inferior gluteal remains posterior Inferior epigastric deep to the rectus muscle, superficial epigastric superficial to the rectus muscle -- in subcutaneous layers (both off the external iliac artery) Specimens week 1 **The fascia of which muscle serves as the attachment for the levator ani muscles? And which of the levator ani specifically originates from there?** - **The fascia overlying the obturator internus are the origin point for the levator ani, especially for the iliococcygeus muscle** **What gaps exist between these muscles where neurovasculature can pass through?** - **Greater Sciatic Foramen -- between inferior border of greater sciatic notch of pelvis and the superior border of the sacrospinous ligament -- subdivided by piriformis muscle and thus makes the sciatic nerve compressible by piriformis pathology** - **Lesser Sciatic Foramen -- inferior to sacrospinous ligament, posterior to ischial tuberosity and anterior to sacrotuberous ligament** - **Obturator foramen -- posteroinferior to superior pubic ramis, and superolateral to obturator membrane and obturator internus** - **Ischiorectal fossa -- lateral to levator ani, medial to obturator internus, inferior to arcuate ligament and superior to urogenital triangle** **Hypertrophy in the obturator internus can compress both obturator and pudendal neurovascular bundles** **How far should I insert my finger in anus to feel the prostate? And what part of anal canal do we palpate to feel the prostate?** - **The anus goes up about 3-4cm, the prostate can be palpated at the very distal part of the rectum -- and hence as we gotta go into the rectum, digital rectal exam causes us to need to go up about 5-6cm -- and palpate the anterior wall of course as the anus posterior to prostate** **Pelvic prpolapse is where the passive supports of the pelvic organ are lengthened or damage and the organs become more mobile, descending in the pelvis under load. Anterior vaginal wall has a large bulge in it going posterior, what was it that prolapsed?** - **The anterior vaginal wall lies just posterior to the bladder and urethra** - **If the passive supports of either (ligaments/fascia -- not muscles as those are active) are damaged, then they can migrate inferoposteriorly and create an indentation in the anterior abdominal wall** **Identify any vessels supplying/draining the pelvic viscera that do NOT originate from the iliac vessels** - **Gonadal arteries** - **The gonads originally arise in the abdomen, hence gonadal vessels also come off the aorta as they're originally embryologically derived too** **Ureter relationship to the pelvic vessels, why is it important to be careful when ligating the uterine arteries in a hysterectomy?** - **The ureter passes posterior to the uterine artery as it travels into the posterior aspect of the bladder from the posterior body wall -- water under the bridge** **What vessels travel with neuralk structures -- what foramens do they pass through to exit the pelvis?** - **Obturator nerve, artery and veins -- pass through the obturator canal** - **Superior gluteal nerve and artery -- greater sciatic foramen suprapirifomic section** - **Inferior gluteal nerve and artery -- greater sciatic foramen infrapiriformic section** **Neuropraxia (transient dysfunction of a nerve as a result of traction injury) of the obturator nerve is often screened for following childbirth -- why is the obturator nerve more at risk?** - **Obturator nerve takes a long journey through the pelvis, goes from posterior to anterior pelvis along the lateral wall, susceptible to inferior traction as the baby moves through pelvis.** - **In contrast, the sacral nerve roots for the sciatic nerve only pass through the pelvis for a short time, mremaining close to the posterolateral pelvic wall before passing through the greater sciatic foramen** **ANATOMY TUTORIAL** **Discuss the structures associated with the uterus that need to be divided to peform a hysterectomy** **Simple hysterectomy** - **Removal of uterus and cervix, vagina and parametrium are preserved** - **Preservation of ovaries and fallopian tube** - **Hysterectomy plus bilateral salpingo-oophorectomy** **In general, hysterectomies are recommended when the patrient has a uterine prolapse, adeno orn endometriosis, uterine fibroids or other sources of pain or abnormal bleeding** **Subtotal hysterectomy** - **If there's no risk of cervical cancer or other abnormalities** - **The patient wishes to maintain cervical support for pelvic organs** - **Smaller operation than the total so a quicker recovery** - **Patient wants to preserve sexual sensation associated with the cervix** **How is a hystrerectomy done** - **Abdominal or laparascopic approach or vaginal -- abdominal you have to open a whole abdomen** - **Surgeon closes off the blood vessels that go to the utereus -- ie uterine artery** - **Sugeon locates and carefully avoids damaging the ureters, bladder and blood vessels** - **The body of the uterus is separated form the cervix** **Radical you use when it's crazy and severely damaged** **And prostatectomy -- how does it compare?** **simple or radical** **Simple** - **Only partial removal, through urethra** **Full removal** - **Open incisision** - **Retropubic,** - **Subrapubic** - **Perineal** **Can also cause urinary incontinence and other damage in the area around -- due to nerves, arteries, lymph etc passing** **Compare and conteast the shape and alignment of the bony pelvis across the human spectrum -- descriptions and reported incidence of gynaecoid, android, anthropoid and platypelloid -- why is this present -- research findings on how pelvic shape can affect locomotion** - **Pelvic inlet -- space and shape of pelvic bones, how do they affect childbirth** - **Gynaecoid -- 40-50% of women, more rounded and borad inlet shape, more suited for childbirth and let baby;s head pass through** - **Android -- most commin in men -- more narrow and larger, better for weight distribution -- better for locomotion** - **Platypoid -- hard to do vaginal delivery, most people with this shape have a C-section** - **Anthropoid -- 23.5% of women, can have vaginal delivery but it also is harder than gynaecoid** **Females generally have wider pelvises, men are less wide** - **Locomotion** - **Apes have a narrower and longer pelvis allowing them to move, ours are wider allowing us to move on 2 legs** - **Not much evidence that the gynaecoid pelvis is worse for movement, may actually be more energy** **Indicate effects of pregnancy and parturition on pelvic joints including sacrum movements and pubic symphysis relaxation -- what is the plane of least dimensions and how is it relevant to childbirth?** - **Sacroiliac joint expands during pregnancy to let the baby pass, often they get pain there cause there's more weight pushing on it** - **Parturition -- lumbar spine flattens (space of baby head), base of sacrum drops downwards and eventually tilts forward** **Pubic symphysis sits at bottom of pelvis, pubic symphysis dysfunction -- produce relaxin causing the ligaments to loosen -- joint becomes more flexible which lets pelvic bones separate, but if it stretches too far then causes pain and instability, depending on how the baby'\[s weight and pressure is distributed -- can cause discomfort and pain on back** **Plane of least dimensions -- smallest part of pelvis the baby has to pass through** - **Transverse = between ischial tuberosities** - **AP -- pubis to sacrococcygeal joint** - **The diagonal circumference is most important, needs to be over 11.5 cm for a birth to actually be possible** - **Typically where labour may slow down or stall, as it is the narrowest point, esp if the baby's head does not adequately descend** - **CPD -- baby's head is too large to descend through the pelvis** **Discuss importance of pelic diaphragm in fecal and urinary incontinence -- how do the divisions of the levator ani (esp puborectalis) associate with pelvic organs, and how does weakness in the pelvic diaphragm cause prolapse in pelvic organs?** **Levator ani** - **Puborectalis -- forms the sling around the lower rectum (important in maintaining fecal ciontinence) -- acts with the anal sohincters In defacation too** - **Pubococcygeus -- important in controlling urine, could play a role in urinary incontinence -- supports vagina and prostate, also has oles in ejacuklation and childbirth** - **Iliococcygeus -- anchoring point for the pelvic floor** **All symmetrical** - **Puborectalis normally constricted, keeping the EAS closed, if it relaxes unnecessarily we get fecal incontinence, same for pubococcygeus in relation to urinary incontinence** - **Pelvic prolapse, when a pelvic organ flals out of its position, increased pressure in the abdomen and the organ falls out of its diaphagm -- could be due to coughing, or pregnancy** - **Could be uterus, rectum or bladder that all could fall out -\> at risk because the whole weight of the body press on them** **Week 2 imaging** ***[LEARNING OBJECTIVES]*** - ***Revise the gross anatomical structures of the external genitalia, correlate them with MRI imaging*** - ***Examine a hystero-salpingogram. Course the path og an egg from the ovary to the uterus and identify where fertilisation occurs on average*** - ***Examine a cysto-urethrogram, identify stricture points and revise implications for catherterisation*** - ***Examine branches of internal pudendal artery on arteriogram, identify major vessels delivering blod to external genitalia and anus*** **How to approach a pelvic X-ray** **Three rings** - **Main pelvic ring and 2 obturator foramina, if a ring is disrupted, think fracture then look for a second one** **Joint spaces** - **Sacroiliac joints symmetrical, joint space range 2-4mm** - **Symphysis pubis joint space \ urinary bladder, uterus, rectum** - **Men -\> urinary bladder, rectum** **Intraperitoneal spaces?** - **Women -\> vesicouterine, rectouterine (pouch of Douglas)** - **Men -\> Rectovesical** **Internal iliac arteries and veins** - **Internal iliac artery a branch of common oiliac** - **Internal iliac vein a tributary of common iliac vein** **Plane of least dimensions** - **The pelvic outlet -- midplane of the pelvis!** - **Narrowest part of the birth canal and can be a limiting factor in vaginal delivery** - **Average diamrter in women is 10-11cm, this can vary though!** **Reasons for variation in pelvic bony anatomy** - **Genetic factors** - **Evolutionary factos** - **Mechanical stresses** - **Nutritional status** - **Etc** **[Week 2]** **What is the perineum, what structures comprise it?** - **It is the region between thighs, from pubic symphysis to coccyx** - **External genitalia and anus contined in it** - **Perineal membrane, deep/superficial perineal pouches** - **Anal canal** - **Superficial fascia** **Shape of pelvic diaphragm** - **U shaped, gap between the 2 halves anteriorly at the pubic bones** - **Vagina and urethra traverse this** **Triangular regions of the pelvic outlet** - **Anal triangle** - **Urogenital triangle** **Vessels accompanying the pudendal nerve** - **Internal pudendal artery and vein** **Foramina for pudendal nerve** - **Travels out through the GSF, travels back into the pelvis through the LSF** - **The nerve courses around the ischial spine (as mentioned in a previous question) which seperates these 2 foramina** **Location of the dentate line** - **2cm above the anal verge in the anal canal** - **Junctiron between embryonic hindgut and the proctodeum (memorise) -- anatomical landmark** **Vessels going to perineum/glutes** - **Superior/inferior gluteal nerves** - **Sciatic nerve** **Perineum** - **Pudendal** - **Klateral femoral cutaneous nerve (perineal branch)** **Clinical Cases of the Pelvis** **Kade's accident?** - **19 years old, brought to hospital after being hit by a car, speeding around the rcorner** - **Resp rate 30, SpO2 88, HR 135, systolic blood pressure of 69mmHg,** - **Groaning of pain, bruises over pelvis, chest and abdoimen, pelvic binder has been applied for a suspected pelvic fractyre** **Where in the body could large volumes of blood accumulate in that patient following the trauma and why? Define space** **Retroperitoneal -- behind the peritoneum** **Intraperitoneal -\> potrntially -- the blood could accumulate in the true pelvis part (ie rectovesical) -- anterior abdo wall is flexible and fluid could accumulate, causes abdominal distension** **Lesser sac -- between stomach and liver posterior** - **Greater sac is anterior side, stomach to intestine** **Bleeding in thigh? We'd see lots of swelling** **Low oxygen, high heart rate -- pleural cavities -- haemothorax -- normally only a thin film of fluid, but we could lose a high degree of fluid in that space** **pericardial cavity (how tf do we actually get this to bleed -- and would cause cardiac tamponade to stop bleeding etc) -- tough fibrous layer is not necessarily expansible** - **Normal rate = 12-16 resp, but under 20 isnt a concern** **Next step of case** - **Chest and pelvis x-rays are performed in the trauma bay -- right sided haemopneumothorax (blood and air) -- treater with intercostal catheter insertion** - **Pelvis x-ray shows disruprtion of pubic symphysis and multiple pubic rami fractures** - **Trauma reg does a bedside ultrasound to determine fluid in the rectovesical pouch (intraperitoneal space)** - **Arrange a CT scan with contrast to work out where the blood is** **Answers** - **Bleeding needs to be intraperitoneal...** - **Fractured bone surfaces -- the bleeding needs to be intraperitoneal and these aren't, I guess the top side of the bone is intraperitoneal** - **Internal pudendal -- all in pelvis or peritoneum -- runs inferior in pelvis -- but abnormal anatomy is messed up due to fracture!** - **Superior gluteal -- too posterior --GSF posterior** - **Obturator artery -- not really intraperitoneal. (anteroinferior on the lateral pelvic wall)** - **Common iliac artery -- definitely could be** - **Tributaries of internal iliac vein -- definitely could be** - **Bleeding from another region -- possible tbh... but not main cause** - **Veins are more susceptible to distension due to thinner wall (so they could theoretically tear first? But bleeding would be lower)** **Final segment** - **Given pelvic fractures identified, the team are concerned about damage to other pelvic structures** - **What else is at risk and would need to be evaluated for injuries?** **Answers** - **Bladder as it's anterior - haematuria** - **Pudendal nerve, obturator nerve (ESPECIALLY as the obturator canal is right near the pubis), femoral nerve, sciatic all at risk** - **Prostate, urethra, testes (maybe less so due to testicular artery coming off aorta but surely they got crushed)** - **Root of penis** **Notes** - **The peritoneal cavity is continuous with the abdomen, fluid can pool within pelvic cavity (rectovesical pouch) but bleeding could be from a variety of sources in abdominopelvic cavity** - **Greater pelvis superior to pelvic inlet (false pelvis), lesser (true) pelvis is inferior to pelvic inlet, contains structures like the rectum and urinary bladder** - **Pelvic fractures are associated with a significant risk of haemorrhage, can be from arteries, veins or the fractured bone** - **Binding pelvis reduces the pelvic volume (creating a tamponade effect) and temporarily stabilises fracture fragments (reducing haemorrhage from fractures) -- essentially a sophisticated belt to push the pubic symphysis together** - **Consider structures related to pelvic fractues which may aso be injured, especially rupture of urinary bladder and urethra -- can be indicated by blood at the penile meatus** ***[CASE 2 - Pat's pelvic discomfort]*** - **Pat writes they are 33 years old, identify gender as woman/female -- primary reason for visit is pelvic discomfort** - **Discomfort has lasted for years, has a feeling of "heaviness" and "dragging" that worsens towards thr end of the day** - **She is otherwise well -- has 3 children** - **She would also want to disacuss management of her varicose veins** **What additional info would you prioritise?** - **Anything history related -- menstrual, obstetric** - **Non-invasive exams, ie lower limb vasculature** - **Abdominal exam** - **Leave the scans until we have more information about what happened** - **Who actually had the kids** - **Pill can cause varicose veins -- does that cause any other symptoms** **What are the top differentials?** - **Endometriosis -- lots of cramps, so could be** - **UTI (several years???)** - **Uterine fibroid -- lots of bleeding??** - **Pelvic congestion syndrome -- defined as heaviness, poor venous drainage causing discomfort** - **Cervical cancer** - **Pelvic inflammatory disease -- could just cause pelvic pain** - **Menorrhagia ? only during menstrual flow** - **Pelvic organ prolapse -- this would likely hurt more** - **Pelvic congestion syndrome ius the ovarian homologue of testicular varicocele, commonly missed cause of chronic pelvic pain, associated with varicose veins in the vulva and lower limb -- incompetent valves in ovarian vein and obstruction to venus outflow** - **Compression of the left renal verin at junction site with ovarian vein -- nut cracker syndrome** - **Compression by retroperitoneal pathology? Ie the lymph nodes** - **Obstruction by tumour or clot in the vein?** - **Treatment option include ovarian vein embolization (endovascular procedure** **Multiple overlapping soruces of venous drainage of \[elvis and perineum in women** - **Anastomoses between ovarian venous systema nd internal iliac vein system** - **Venous drainage of perineum is through internal pudendal vein (branch of internal iliac) and external pudendal vein (branch of great saphenous vein)** - **Can get vulval varices or even lower limb varices as a consequence** ***[CASE 3 -- Belinda's difficulty walking]*** - **Belinda is 1 day post c section of a healthy infant** - **She laboured for many hours and used an epidural for pain management -- put this below the cauda equina** - **Midwife got concerned, they used a C section, baby seems fine** - **When attempting to walk for the first time, belinda experiences difficulty controlling her left leg** - **Lower leg neuro exam gets 3/5 for left hip adduction** - **Sensation is normal bilaterally, she has a urinary catheter in situ and has not opened her bowels since Caesarean** **Which is best explaining belinda's presentation and why?** - **Obturator and femoral are BOTH L2-L4** - **Cauda equina syndrome -- issues with the bottom of the spinal cord -- severe low back pain, difficulties getting up (more sciatic nerve) -- L1-L5** - **This gotta be obturator nerve -- issues with the ADDUCTORS (medial side of the thigh)** **Lower limb neuro symptoms can arise due to the compression of nerves in the pelvis, post partum neuropathy is usually related to the stretch or compression of nerves relating to ligaments and bony prominences by the foetal head, forceps or prolonged extremes of positioning (labouring for hours)** - **Obturator nerve innervates a small area of skin on the mid thigh -- medial femoral cutaneous nerve does the rest but comes off the femoral** ***[CASE 4 -- Huy's fever]*** - **35 years old, goes to the ED after having groin pain and fevers the past few hours. Huy has type 1DM and reports recent difficulties controlling his BGL** - **120bpm, hypotensive \*90/40), resp rate 30, fever -- 39.5** - **Crepitus in inguinal region -- indurated and hot to touch** - **Scrotum swollen and oedematous** - **Phimosis (difficulty pulling back femur skin)** **What is the next step in your care for Huy** - **Keep him in the hospital** - **Swab and culture** - **Septic shock? High HR, low BP, fever** - **If it's sepsis, do we put him on antibiotics** - **Doxycycline and penicillins** - **Gas gangrene and necrotising fasciitis? -- the crepitus is due to gas buildup, hence we got to treart the bacteria and also debride the tissue** **Urgently taken to operating theatre by gen surg which makes an incision in skin over inguinal region** **Fournier gangrene -- necrotising fasciitis of the perineum, dishwasher fluid present everywhere -- erythema, very severe pain, blistering** **Infection and necrosis spread upwards into the ASIS and inguinal region, but testes and the spermatic cord were spared?** **Definitive diagnosis is established by surgical exploration** **Which layer prevented the spread of infection into the spermatic cord and testis?** **In this case, scrotum and perineal skin are necrosed but spermatic cord and testis are spared -- suggests the external spermatic fascia (outermost layer of spermatic cord) is currently intact -- even if camper's and scarpa's are broken/pierced** - **Deep layers commence with the external oblique/external spermatic fascia -- this is currently preventing spread to spermatic cord and tissue** - **Camper's = adipose, only exists in abdo wall and perineum** - **Scarpa's = membranous, becomes dartos on penis, colles on perineum** **Understanding fascial layers and spaces can predict how infection will spread** **Layers of perineum** - **Adipose layer** - **Membranous layer** - **Perineal investing fascia of Gallaudet = deep fascia** - **Perineal membrane** - **Anterior recesses of ischioanal fossa** **The ischioanal fossa is continuous with the actual skin of the perineum, so infections can bypass these layers by going posteriorly through anal triangle and then through the anterior side of the ischioanal fossa** **In an AP xray, the posterior side is closer to the detector** **Tutorial week 2** **Describe the fascial planes of the perineum and the possible routes taken by iunrections, correlate these fascial planes with thise covered in the abdominal unit** - **Superficial perineal fascia is continuous from the Scarpa fascia from the abdomen (deeper layer of the superficial fascia of the abdomen) -- under Camper's and becomes the Colles fascia -- attaches to the fascia lata of the thigh laterally and posterior perineal membrane (memorise)** - **Deep perineal fascia (perineal membrane) -- tough triangular m,embrane whoich spans the ANTERIOR half of the pelvic outlet - pierced by urethra and vagina** - **The third layer of fascia is the visceral fascia to the levator ani and coccygeus muscles -- as we know, these muscles help to maintain continence and support the pelvic floor** - **Superficial perineal space infections -- can spread to the scrotum, penis, labia and anterior abdominal wall** - **Limited posteriorly by colles attaching to pertineal gangrene** - **Fournier's gangrene is a necrotising fasciitis of the perineal and genital regions, lifethreatening if not treated quickly** - **Deep infections can spread to the pelvis and ischianal fossa and then posterior -- retroperitoneal space infections can descend into deep perineal space** **Superficial perineal fascia (colles') is continuous with Scarpa's and dartos fascia of scrotum and penis** **Deep perineal = transverslais fascia** **Pelvic diaphragm = continuous woth transversus abdominus** **Embryology of pectinate line** **Upper side is endoderm, bottom is ectoderm** **Upper is columnar epithelium, lower is stratified squamous** **Above is superior rectal artery, off the inferior mesenteric, inferior is from the internal pudendal, m,idle from the internal iliac arteriwes** **Lumph comes from ther internal iliac, lower part goes to superficial inguinal nodes -- anal cancers would spread into either dplace depemnding on where they are** **Hypogastric plexus supplies sympathetic, pelvic splanchnics responsible for parasympathetic** **Veins either go portal system (upper) or to systemic (lower)** **Defecation reflex** - **Simp in love with someone, sympathetic wants to keep the feces -- relax the recum and constrict the internal anal sphincter** - **Parasympathetics (pelvic splanchnic) will constrict the rectum and relax IAS** **Course of the urethra** **Women 3-4cm in front of vagina** **Men -- 20cm -- 3 sections = first = prostatic -- straightest and widest, then membraneous -- surrounded by EUS and is narrowest, and then bulbar, longest and runs up to the external urethral orifice** **Angles** **Prepubic angle -- spongy urethra (curves down)** **Infrapubic angle -- membranous urethra (curves up)** **Catheterisation** - **Patient will be flat on back, make sure the area is clean** **In women** - **Folle catheter, keep ballon little until it gets to bladder, second section with water = more inflation and see if it gets loose (pls do not do in males)** - **Make sure you insert it ALL the way in, then inflate balloon (DO NOT TUG)** **Anatomical predisposition to UTIs** - **Females have a shorter urethra, closer proximity to bacteria** - **Vaginal delivery is a major UTI concern, pelvic organ prolapse** - **Pelvic outlet obstruction, lesions -- stone or catheter intraluminal** - **Intramural, extramural or intraluminal are the classes** **Contrast the pathways of somartic and autonomic innervation to the external genitalia and perineum** **Somatic** - **Pudendal nerve ocmes off S2-4** - **3 branches -- inferior rectal nerve (EAS), perineal nerve (to scrotum or also to the labial branches in women), dorsal mnerve of penis and clitoris** **Autonomics** - **T12-L2 (potentiall L1-L4) -- sympathtetics -- lumbar splanchnics, synapse para-aortically** - **Travel down from ovarian (pelvic) plexus** - **Below cervix, pelvic splanchnics (S2-S4) -- inferior hypogastric plexus** - **First 1/3 of the uterus -- lumbar splanchnics,** - **Below this to the vaginal opening -- pelvic splanchnic nerves** - **Lowest down somatics -- pudendal** **What do the autonomics do?** - **Smooth muscle of clitoris crura relaxes -- parasympathetics** - **Reflex arc of bulbospongiosus/ischiocavernosis -- parasympathetic** - **Skenes/greater vestibular gland -- somatic** - **Contraction of bulbo/ischio -- somatic** - **Smooth muscle relaxes to increase blood flow -- sympathetic** **Sympathetics want to increase blood flow to the erectile tissue** **Parasympathetics decrease it** **Pudendal nerve causing cancer issues or erection?** - **Can cause erectile dysfunction as the muscles can't function properly after prostate or rectal surgery due to hitting pudendal nerve** - **If we remove the testes, we lose testosterone (cannot maintain erections) and also predisposes everyone to cancer** - **Pudendal nerve innervates bulbospongiosis and ischiocavernosus, causing them to contract, blood to remain in the erectile tissues -- if this nerve is impeded, then the blood drains out, no erection** **Organisation of the Neck** ***[LEARNING OUTCOMES]*** - ***Orient the head and neck to other regions of the body*** - ***Differentiate between visceral and non-visceral spaces*** - ***Demonstrate the embryological and anatomical importance of the pharynx in connecting the visceral spaces*** - ***Introduce fasciae in the head and neck*** - ***Introduce cranial nerves as an important area of study*** **Overview and orientation to the head and neck** **Dorsal (for CNS)** - **Cranial (brain)** - **Vertebral (spinal cord)** **Ventral (divided by diaphragm)** - **Thoracic** - **-\> mediastinum (heart)** - **-\> pleural (lungs)** - **Abdominopelvic** - **-\> abdominal organs** - **-\> pelvic organs** **Visceral vs nonvisceral spaces** **Visceral -- some organs/sensory structures** - **Cranial cavity** - **Ear** - **Orbital cavity** - **Nasal cavity** - **Oral cavity** - **Pharynx** - **Larynx** **Non-visceral (muscular/neurovascular)** - **Face** - **Infratemporal fossa** - **Musculoskeletal neck** **Face and scalp** - **Superficial region housing the muscles of facial expression** - **Unlike other muscles we've seen in anatomy -- almost evrrywhere else, musclesa are deep to deep fascia** - **In the face, the muscles are in the hypodermis -- subcutaneous fascia as they need to move** - **Clinically important anastomoses with orbit and cranial cavity**  **Infra fossa** - **Muscles of mastication -- manipulate mandible for chewing** - **Deep to mandible, anterior to the ear** - **Deepest part connects with the pterygopalatine fossa -- one of the 4 important parasymnpathetic ganglia of the head, the pterygopalatine ganglion** - **Other ones include the otic ganglia -- infratemporal fossa, ciliary in orbital cavity and submandibular in the oral cavity** - **Pterygopalatine fossa is a complicated, tiny space, connecting to other parts of our head -- letting neurovasc communicate with cranial, nasal, oral cavities, orbit and pharynx** **Visceral spaces = areas with sensory organs/special senses or speech** **Cause the head and neck is relatively small compared to other regions, spaces are close and ntimite connections with each other** - **Cranial cavity, ear, orbit, nasal cavity nad oral cavity included** - **Inferior we have the laryx and the pharynx**  **Cranial cavity** - **Where brain is loicated** - **Main function is to protect brain** - **Numerous openings in the floor of the cavity to let spinal nerve and spinal cord to pass through** **Skull** - **Complicated bony structure forming from fusion of 24 bones** - **Neurocranium -- 8 bones to protect brain (4 unpaired, 3 paired)** - **Face -- 14 bones - 2 unpaired, 6 paired** - **Most bones bilateral, some unilateral**  **Ear** **3 subdivisions** **External ear -- fleshy auricle** **Middle ear -- smallest bones in body which convert air vibrations to fluid waves** **Inner ear -- interprets fluid waves as sound, has a sense of balance -- travels to nasopharynx** **Small space to dissect, lots of nerves travelling and branching within middle ear** **Orbital cavity** - **Much larger space, but complex** - **Muscle sthat move the eye (6 of them), the eye, lacrimal (tear) gland, and all of the neurovascuklature which supports this and enters face/nasal cavity** - **Connection with nasal cavity via nasolacrimal duct -- gutter for tears, as we secrete tears to moisten eye, they get drained into nasal cavity** - **Hence we get tears and also a runny n