Pelvis and Perineum PDF

HAYAT MEDICAL COLLEGE PELVIS AND PERINEIUM By Solomon Seyoum (MSC in Anatomy, MPH) October, 2024 G.c. 1  PELVIC VISCERA The pelvic viscera include the 1- Distal parts of the urinary system - Pelvic part of uret...

HAYAT MEDICAL COLLEGE PELVIS AND PERINEIUM By Solomon Seyoum (MSC in Anatomy, MPH) October, 2024 G.c. 1  PELVIC VISCERA The pelvic viscera include the 1- Distal parts of the urinary system - Pelvic part of ureter - bladder - Pelvic part of urethra 2- Reproductive system. - Female internal genital organs - Male internal genital organs 3- Digestive tract - rectum  Rectum  The rectum is the pelvic part of the digestive tract  The rectum is about 5 in. (13 cm) long  It is continuous proximally with sigmoid colon and distally with anal canal.  The rectosigmoid junction lies anterior to the S3 vertebra. At this point, the  teniae of the sigmoid colon spread to form a continuous outer longitudinal layer of smooth muscle  fatty omental appendices are discontinued.  The lower part of the rectum is dilated to form the rectal ampulla  Rectum  The ampulla of the rectum  It is the dilated terminal part of the rectum  It is lying directly superior to and supported by the pelvic diaphragm (levator ani) and anococcygeal ligament  It receives and holds an accumulating fecal mass until it is expelled during defecation.  The ability of the ampulla to relax to accommodate the initial and subsequent arrivals of fecal material is another essential element of maintaining fecal continence.  Rectum  The puborectalis portion of the levator ani muscles forms a sling at the junction of the rectum with the anal canal and pulls this part of the bowel forward, producing the anorectal angle.  The peritoneum covers the  anterior and lateral surfaces of the first third of the rectum  only the anterior surface of the middle third  the lower third devoid of peritoneum.  Rectum  The muscular coat of the rectum is arranged in the usual outer longitudinal and inner circular layers of smooth muscle. However, the three teniae coli of the sigmoid colon come together so that the longitudinal fibers form a broad band on the anterior and posterior surfaces of the rectum.  The mucous membrane of the rectum, together with the circular muscle layer, forms two or three semicircular permanent folds called the transverse folds of the rectum. They vary in position.  Rectum Relations  Posteriorly: The rectum is in contact with the  sacrum and coccyx;  piriformis, coccygeus, and levatores ani muscles;  sacral plexus; and  sympathetic trunks  Rectum Relations  Anteriorly: In the male,  the upper two thirds of the rectum is related to the sigmoid colon and coils of ileum that occupy the rectovesical pouch.  The lower third of the rectum is related to the posterior surface of the bladder, to the termination of the vas deferens and the seminal vesicles on each side, and to the prostate. Figure - Sagittal section of the male  Rectum Relations  Anteriorly: In the female  the upper two thirds of the rectum is related to the sigmoid colon and coils of ileum that occupy the rectouterine pouch.  The lower third of the rectum is related to the posterior surface of the vagina. Figure - Sagittal section of the female pelvis.  ARTERIAL SUPPLY AND VENOUS DRAINAGE OF RECTUM Arterial supply of rectum  The superior rectal artery - supplies the proximal part of the rectum.  The right and left middle rectal arteries- supply the middle and inferior parts of the rectum.  The inferior rectal arteries- supply anorectal junction and anal canal.  Anastomoses between the superior and inferior rectal arteries may provide potential collateral circulation.  The veins of the rectum  correspond to the arteries.  The superior rectal vein is a tributary of the portal circulation and drains into the inferior mesenteric vein.  The middle and inferior rectal veins drain into the internal iliac and internal pudendal veins, respectively.  The union between the rectal veins forms an important anorectal portal–systemic anastomosis  Lymph Drainage  The lymph vessels of the upper rectum drain first into the pararectal nodes and then into inferior mesenteric nodes.  Lymph vessels from the lower part of the rectum follow the middle rectal artery to the internal iliac nodes.  Nerve Supply  The nerve supply is from the sympathetic and parasympathetic nerves from the inferior hypogastric plexuses.  The rectum is sensitive only to stretch. nervation of rectum and anal canal Internal Genital Organs  Female Internal Genital Organs  Include the ovaries, uterine tubes, uterus, and vagina. OVARIES  Are oval shaped, measuring 4 by 2 cm.  the ovaries develop high on the posterior abdominal wall and then descend before birth  Each ovary is suspended by a short peritoneal fold or mesentery called the mesovarium.  They usually lies against lateral wall of the pelvis in a depression called the ovarian fossa.  In prepubertal females  the ovaries are surrounded by the tunica albuginea - the CT capsule comprising the surface of the ovary.  the tunica albuginea is covered externally by a smooth layer of ovarian mesothelium or surface (germinal) epithelium a single layer of cuboidal cells that gives the surface a dull, grayish appearance  After puberty 15  Female Internal Genital Organs  Before puberty, the ovary is smooth  After puberty, the ovary becomes progressively scarred as successive corpora lutea degenerate.  After menopause, the ovary becomes shrunken and its surface is pitted with scars. The suspensory ligament of the ovary  Is the part of the broad ligament extending b/n the attachment of the mesovarium and the lateral wall of the pelvis. The round ligament of the ovary  It connects the lateral margin of the uterus to the ovary. Functions of ovary  The ovaries are the organs responsible for the production of the  female germ cells, the ova  female sex hormones, estrogen and progesterone, in the sexually mature female. 16 Ovary 17  Uterine tubes  It extends laterally from the uterine horns and open into the peritoneal cavity near the ovaries.  Is approximately 10 cm long.  lie in a narrow mesentery (the mesosalpinx) forming the free anterosuperior edges of the broad ligaments.  The uterine tubes are divided into four parts, from lateral to medial: 1- Infundibulum:  Is the funnel-shaped distal end of the tube.  It opens into the peritoneal cavity through the abdominal ostium.  The free edge of the funnel has several finger like processes, known as fimbriae. 2- Ampulla:  Is the widest and longest part of the tube, which begins at the medial end of the infundibulum.  Is the where fertilization of the oocyte usually occurs 18  Uterine tubes 3- Isthmus:  Is the thick-walled part of the tube, which enters the uterine horn.  Is the narrowest part of the tube and lies just lateral to the uterus. 4- Uterine part:  Is the short intramural segment of the tube.  It passes through the wall of the uterus and opens via the uterine ostium into the uterine cavity at the uterine horn. 19  Uterine tubes Function  It receives the ovum from the ovary and provides a site where fertilization of the ovum can take place.  It provides nourishment for the fertilized ovum and transports it to the cavity of the uterus.  It serves as a conduit along which the spermatozoa travel to reach the ovum.  Arterial Supply and Venous Drainage of Ovaries and Uterine Tubes. Arterial supply  Arises from ovarian arteries and ascending branches of the uterine arteries  The ovarian arteries arise from the abdominal aorta  They terminate by bifurcating into ovarian and tubal branches. 20  Uterine tubes Venous drainage  The right ovarian vein ascends to enter IVC.  The left ovarian vein drains into the left renal vein.  The tubal veins drain into the ovarian veins and uterine (uterovaginal) venous plexus. Lymph Drainage  The lymph vessels of the ovary follow the ovarian artery and drain into the para-aortic nodes at the level of the 1st lumbar vertebra.  Lymph from uterine tube drain to the  internal iliac and para-aortic nodes. Blood supply and venous drainage of uterus, vagina, 21  Uterine tubes Innervation of Ovaries and Uterine Tubes  The nerve supply derives.  partly from the ovarian plexus, descending with the ovarian vessels.  partly from the uterine (pelvic) plexus. 22  Clinical anatomy Ectopic pregnancy  Tubal pregnancy 23  Clinical anatomy Tubal ligation  surgically ligate (clip) the uterine tubes  preventing spermatozoa from reaching ova 24  Uterus (womb)  Is a thick-walled, pear-shaped, hollow muscular organ.  The embryo and fetus develop in the uterus.  Its muscular walls adapt to the growth of the fetus and then provide the power for its expulsion during childbirth.  The non-gravid (non-pregnant) uterus  Usually lies in the lesser pelvis, with its: body lying on the urinary bladder cervix between the urinary bladder and rectum.  Is ~ 7.5 cm long, 5 cm wide and 2 cm thick and weighs approximately 90 g.  The uterus is divided into two main parts:  The body  cervix. 25  Uterus (womb) The body of the uterus  Forms the superior two thirds of the organ.  Includes the fundus of the uterus  Fundus is the rounded part that lies superior to the uterine ostia.  It has two surfaces:  vesical (related to the bladder) and intestinal.  Is demarcated from the cervix by the isthmus of the uterus  the isthmus of the uterus  It is a relatively constricted segment  It is approximately 1 cm long. 26  Uterus (womb) The cervix of the uterus  Is the cylindrical, relatively narrow inferior third of uterus.  It is approximately 2.5 cm long in an adult non-pregnant woman.  It has two parts: 1- A supravaginal part  Is between the isthmus and the vagina.  Is separated from the  bladder anteriorly by loose CT  from the rectum posteriorly by the rectouterine pouch. 2- A vaginal part  Protrudes into the vagina.  It surrounds the external os of the uterus.  It is surrounded by a narrow recess called 27 vaginal fornix.  Lifetime Changes in Normal Anatomy of Uterus  The uterus is possibly the most dynamic structure in human anatomy.  At birth  the uterus is relatively large  has adult proportions (body to cervical ratio = 2:1)  In childhood  Uterus body to cervical ratio=1:1 with cervix having greater diameter (thickness).  In infancy the uterus is mainly an abdominal organ. Because of the small size of the pelvic cavity during infancy.  During puberty  the uterus assumes adult proportions (body to cervical ratio = 2:1)  In the postpubertal, premenopausal, non-pregnant woman  Uterus body to cervical ratio = 2:1  In multiparous women = body to cervical ratio is 3:1  In postmenopausal women = body to cervical ratio is 1:1 28 Lifetime Changes in Normal Anatomy of Uterus 29  Uterus (womb) Uterine cavity  Is approximately 6 cm in length.  Extends from the external os to the wall of the fundus.  The uterine horns  Is the superolateral regions of uterine cavity, where uterine tubes enter.  It continues inferiorly as the cervical canal.  The uterine cavity (in particular, the cervical canal) and the lumen of the vagina together constitute the birth canal. The 3 layers of The wall of the body of the uterus are: 1- Perimeterium:  It is the outer layer of uterine wall. 30  Uterus (womb) Myometrium  Is the middle layer which contains smooth muscle.  The main branches of the blood vessels and nerves of the uterus are located in this coat.  During childbirth, contraction of the myometrium dilate the cervical os and expel the fetus and placenta.  During the menses, myometrial contractions may produce cramping. Endometrium  Is the inner mucous layer  It is actively involved in the menstrual cycle, differing in structure with each stage of the cycle.  If conception occurs  the blastocyst becomes implanted in this layer.  if conception does not occur,  the inner surface of this layer is shed during menstruation. 31  Uterus (womb) Positions of the Uterus Anteversion of the uterus  The position of uterus in which the long axis of the uterus is bent forward on the long axis of the vagina. Anteflexion of the uterus  The position of uterus in which the long axis of the body of the uterus is bent forward at the level of the internal os with the long axis of the cervix. Retroverted  The position of uterus in which the fundus and body of the uterus are bent backward on the vagina so that they lie in the rectouterine pouch (pouch of Douglas). Retroflexed 32  The position of uterus in which the body of the  Uterus (womb) Relations of the uterus: Anteriorly:  The vesicouterine pouch and superior surface of bladder.  The supravaginal part of the cervix is related to the bladder. Posteriorly:  The rectouterine pouch containing loops of small intestine and the anterior surface of rectum. Laterally:  The body of the uterus is related laterally to the broad ligament and the uterine artery and vein.  The supravaginal cervix is related to the ureter as it passes forward to enter the bladder.  The vaginal cervix is related to the lateral fornix of the vagina.  The uterine tubes enter the superolateral angles of the uterus, and the round ligaments of the ovary and of the uterus are attached to the uterine wall just below this level. 33 Function Relationship of the female pelvicviscera 34  Supports of the Uterus  The uterus is supported By.  pelvic diaphragm  ligaments Ligaments of Uterus  the ligament of the ovary  It attaches to the uterus posteroinferior to the uterotubal junction  The round ligament of the uterus = connect uterus to labia majora  The broad ligament of the uterus  is a double layer of peritoneum (mesentery) that extends from the sides of the uterus to the lateral walls and floor of the pelvis.  This ligament assists in keeping the uterus in position.  The largest part of the broad ligament, inferior to the mesosalpinx and mesovarium, which serves as a mesentery for the uterus itself, is the mesometrium. 35  Supports of the Uterus  Cardinal (transverse cervical) ligaments  It extend from the supravaginal cervix and lateral parts of the fornix of the vagina to the lateral walls of the pelvis.  Uterosacral ligaments  It pass superiorly and slightly posteriorly from the sides of the cervix to the middle of the sacrum.  they are palpable during a rectal examination.  Pubocervical Ligaments  Consist of two firm bands of connective tissue that pass to the cervix from the posterior surface of the pubis. 36  Uterus (womb)  The arterial supply to the uterus  Is mainly from the uterine artery.  The uterine artery gives off: Descending branch - supplies the cervix and the vagina Ascending branch- gives the ovarian and tubal branch.  The uterine vein follows the artery - Drains into the internal iliac vein. 37  Uterus (womb) Lymph Drainage  The lymph vessels from the fundus of the uterus accompany the ovarian artery and drain into the para-aortic nodes at the level of the first lumbar vertebra.  The vessels from body and cervix drain into the internal and external iliac lymph nodes.  A few lymph vessels follow the round ligament of the uterus through the inguinal canal and drain into the superficial inguinal lymph nodes. Nerve Supply  Sympathetic and parasympathetic nerves from branches of the inferior hypogastric plexuses. 38  Clinical anatomy Cervical Cancer, Cervical Examination, and Pap Smear 39  Clinical anatomy Hysterectomy 40  VAGINA  Is a distensible musculomembranous tube (7-9 cm long).  It extends from the middle cervix of the uterus to the vaginal orifice.  The vaginal orifice, external urethral orifice, and ducts of the greater and lesser vestibular glands open into the vestibule of the vagina.  Communicates superiorly with cervical canal and inferiorly with vestibule of vagina.  The vaginal fornix  Is the recess around the cervix  Has anterior, posterior, and lateral parts.  The posterior vaginal fornix is the deepest part and is closely related to the rectouterine pouch. 41  VAGINA  The vaginal orifice in a virgin possesses a thin mucosal fold called the hymen, which is perforated at its center.  the upper half of the vagina lies above the pelvic floor and the lower half lies within the perineum The vagina is related:  Anteriorly to  the fundus of the urinary bladder and urethra.  Laterally to  the levator ani, visceral pelvic fascia, and ureters.  Posteriorly (from inferior to superior) to  the anal canal, rectum, and rectouterine pouch. The vagina:  It serves as a canal for menstrual fluid.  It forms the inferior part of the birth canal. 42  VAGINA Supports of the Vagina  The upper part of the vagina is supported by the  levatores ani muscles and the transverse cervical, pubocervical, and uterosacral ligaments.  These structures are attached to the vaginal wall by pelvic fascia.  The middle part of the vagina is supported by the urogenital diaphragm  The lower part of the vagina, especially the posterior wall, is supported by the perineal body 43  Clinical anatomy Vaginal Fistulae 44  Clinical anatomy Culdocentesis 45  VAGINA ARTERIAL SUPPLY AND VENOUS DRAINAGE OF VAGINA Arteries supplying the superior part of the vagina  Derive from the uterine arteries. Arteries supplying the middle and inferior parts of vagina  Derive from the vaginal and internal pudendal arteries. The vaginal veins  Form vaginal venous plexuses  are continuous with the uterine venous plexus as the uterovaginal venous plexus and drain into the internal iliac veins through the uterine vein.  This plexus also communicates with the vesical and rectal venous plexuses. Lymph Drainage  The upper third of the vagina drains to the external and internal iliac nodes  the middle third drains to the internal iliac nodes 46  the lower third drains to the superficial inguinal nodes.  Male Internal Genital Organs Male Internal Genital Organs include: the  Testes  Epididymis  Ductus deferens  Seminal glands  Ejaculatory ducts.  Prostate  Bulbourethral glands. Pelvic male internal genital organs are:  Ductus deferens  Seminal glands  Ejaculatory ducts.  Prostate 47  Bulbourethral glands  Ductus deferens (vas deferens)  Is the continuation of the duct of the epididymis.  Has relatively thick muscular walls and a minute lumen, giving it a cord-like firmness.  Begins in the tail of the epididymis, at the inferior pole of the testis.  Ascends posterior to the testis, medial to the epididymis.  Is the primary component of the spermatic cord.  Penetrates the anterior abdominal wall via the inguinal canal.  Crosses over the external iliac vessels and enters the pelvis.  Passes along the lateral wall of the pelvis, where it lies external to the parietal peritoneum.  Ends by joining the duct of the seminal gland to form the ejaculatory duct.  During the pelvic part of its course  the ductus deferens maintains direct contact with the peritoneum; no other structure intervenes between them. 48  Ductus deferens (vas deferens)  The duct crosses superior to the ureter near the posterolateral angle of the bladder, running between the ureter and the peritoneum of the ureteric fold to reach the fundus of the bladder.  Posterior to the bladder  the ductus deferens at first lies superior to the seminal gland, then descends medial to the ureter and the gland.  The terminal part of the vas deferens is dilated to form the ampulla of the vas deferens. 49  Ductus deferens (vas deferens) Arterial Supply and Venous Drainage of Ductus Deferens.  The artery to the ductus deferens  usually arises from a superior (sometimes inferior) vesical artery and  terminates by anastomosing with the testicular artery, posterior to the testis.  Venous drainage  Veins from most of the duct drain into the testicular vein Clinical anatomy  Its terminal portion drains into the vesicular/prostatic venous plexus. Vasectomy 50  Seminal glands  Are an elongated structure (approximately 5 cm long but sometimes much shorter) that lies b/n the fundus of the bladder and the rectum.  Are obliquely placed superior to the prostate. The superior ends of the seminal glands  Are covered with peritoneum and lie posterior to the ureters, where the peritoneum of the rectovesical pouch separates them from the rectum. The inferior ends of the seminal glands  Are closely related to the rectum and are separated from it only by rectovesical septum.  The duct of the seminal gland joins the ductus deferens to form the ejaculatory duct. 51  Seminal glands Function  The function of the seminal vesicles is  to produce a secretion that is added to the seminal fluid.  The secretions nourish the spermatozoa.  During ejaculation, the seminal gland contract and expel their contents into the ejaculatory ducts, thus washing the spermatozoa out of the urethra. Blood vessels of seminal gland  The arteries - derive from the inferior vesical and middle rectal arteries.  Veins  The veins accompany the arteries and have similar names  The veins drain into the internal iliac veins. Lymph Drainage  The internal iliac nodes. 52  Ejaculatory ducts  Are slender tubes that are about 2.5 cm long.  Formed by the union of the ducts of the seminal glands with the ductus deferentes.  Arise near the neck of the bladder.  Pierce the posterior surface of the prostate  Open into the prostatic part of the urethra, close to the margins of the prostatic utricle.  Their function is to drain the seminal fluid into the prostatic urethra. Arterial Supply and Venous Drainage of Ejaculatory Ducts.  The arteries to the ductus deferens, usually branches of the superior (but frequently inferior) vesical arteries, supply the ejaculatory ducts.  The veins join the prostatic and vesical venous plexuses 53  PROSTATE  Is approximately 3 cm long, 4 cm wide  Is the largest accessory gland of the male reproductive system.  Is a fibromuscular glandular organ that surrounds the prostatic urethra.  The glandular part makes up~ two thirds of the prostate; the other third is fibromuscular.  Is surrounded by a fibrous capsule.  The fibrous capsule of the prostate is dense and neurovascular, incorporating the prostatic plexuses of veins and nerves.  All this is surrounded by fibrous prostatic sheath  prostatic sheath is thin anteriorly, continuous anterolaterally with the puboprostatic ligaments, and dense posteriorly where it blends with the rectovesical septum.  The posterior surface of the prostate is pierced by two ejaculatory ducts which open into the prostatic urethra. 54  Prostate  The prostate has  A base closely related to the neck of the bladder. The urethra enters the center of the base of the prostate.  An apex – it is in contact with fascia on the superior aspect of the urethral sphincter and deep perineal muscles. The urethra leaves the prostate just above the apex on the anterior surface.  A muscular anterior surface This surface is separated from the pubic symphysis by retroperitoneal fat in the retropubic space.  A posterior surface  It is related to the ampulla of the rectum.  It is separated from it by the rectovesical septum.  Inferolateral surfaces that are related to the levator ani. 55  PROSTATE Lobes of Prostate  The prostate is divided into five lobes. The anterior lobe - lies in front of the urethra and is devoid of glandular tissue. The median, or middle, lobe  Is situated b/n urethra and the ejaculatory ducts. It is rich in glands.  it tends to undergo hormone-induced hypertrophy in advanced age, and is closely related to the neck of the bladder. The posterior lobe  Is situated behind the urethra and below the ejaculatory ducts and also contains glandular tissue. The right and left lateral lobes  lie on either side of the urethra  are separated from one another by a shallow vertical groove on the posterior surface of the prostate.  The lateral lobes contain many glands. 56 Lobes of prostate 57  PROSTATE  The prostate has three distinct zones:  The central zone occupies 25% of the gland's volume. The central zone is comparable to the middle lobe.  The peripheral zone- occupies 70% of the gland’s volume which is the major site of prostatic cancer.  The transition zone is of medical importance because it is the site at which most benign prostatic hyperplasia originates.  The prostatic ducts (20-30) open chiefly into the prostatic sinuses that lie on either side of the seminal colliculus on the posterior wall of the prostatic urethra. Fig. prostate 58 zones.  PROSTATE Function of the Prostate  It produces a thin, milky fluid that provides approximately 20% of the volume of semen and plays a role in activating the sperms.  The smooth muscle, which surrounds the glands, squeezes the secretion into the prostatic urethra.  Its secretion is alkaline and helps neutralize the acidity in the vagina.  Semen is a mixture of secretions produced by the testes, seminal glands, prostate, and bulbourethral glands that provides the vehicle by which sperms are transported. 59  Clinical anatomy Benign hypertrophy of the prostate (BHP) and DRE 60  PROSTATE  The prostatic arteries  Mainly arises from the inferior vesical arteries  It also the internal pudendal and middle rectal arteries.  The veins join to form prostatic venous plexus.  It is between the fibrous capsule of the prostate and the prostatic sheath  It is continuous superiorly with the vesical venous plexus and communicates posteriorly with the internal vertebral venous plexus.  It receives the deep dorsal vein of the penis and numerous vesical veins.  It drains into the internal iliac veins.  Lymph Drainage= Internal iliac nodes.  Nerve Supply  Inferior hypogastric plexuses.  The sympathetic nerves stimulate the smooth muscle of the prostate during ejaculation 61  Bulbourethral glands (Cowper glands)  Are two pea-size mucous glands.  They are posterolateral to the intermediate part of the urethra, largely embedded within the external urethral sphincter.  The ducts of the bulbourethral glands:  Pass through the perineal membrane with the intermediate urethra  Open through minute apertures into the proximal part of the spongy urethra in the bulb of the penis.  Their mucus-like secretion enters the urethra during sexual arousal. 62  Innervation of the internal genital organs of male Sympathetic nerve fibers pelvis.  Innervates the ductus deferens, seminal glands, ejaculatory ducts, and prostate.  Presynaptic sympathetic fibers  originate from cell bodies in intermediolateral cell column of T12-L2 (or L3) spinal cord segments.  They traverse the paravertebral ganglia of sympathetic trunks to become components of lumbar (abdominopelvic) splanchnic nerves and hypogastric and pelvic plexuses.  The function of the sympathetic innervation  It stimulates contraction of the internal urethral sphincter to prevent retrograde ejaculation.  it stimulates rapid peristaltic-like contractions of the ductus deferens, and the combined contraction of and secretion from the seminal glands and prostate that provide vehicle (semen) and expulsive force to discharge sperms during ejaculation. 63  Innervation of the internal genital organs of male pelvis.fibers Presynaptic parasympathetic  From S2 and S3 spinal cord segments traverse pelvic splanchnic nerves.  The function of the parasympathetic innervation:  Is unclear however, it traverses the prostatic nerve plexus and form the cavernous nerves that pass to the erectile bodies of the penis.  Cavernous nerves are responsible for producing penile erection. 64