The Perineum PDF

The perineum Soressa A (PhD) November 2024  diamond-shaped area extending b/n the two abducted thigh Boundaries: Anteriorly - Pubic symphysis Anterolaterally - Inferior pubic rami and ischial rami,. Laterally - Ischial tuberosities,. Posterolaterally - S...

The perineum Soressa A (PhD) November 2024  diamond-shaped area extending b/n the two abducted thigh Boundaries: Anteriorly - Pubic symphysis Anterolaterally - Inferior pubic rami and ischial rami,. Laterally - Ischial tuberosities,. Posterolaterally - Sacrotuberous ligaments, Posteriorly - Inferiormost sacrum and coccyx,. Surface anatomy best shown when the lower limbs are abducted, and a diamond shape is depicted: Anterior: mons pubis in females, base of the penis in males. Laterally: medial surfaces of the thighs. Posterior: superior end of the intergluteal cleft.  Transverse line joining the anterior ends of the ischial tuberosities divides the diamond-shaped perineum into two triangles The midpoint of the line joining the ischial tuberosities is the central point of the perineum is the location of the perineal body The perineal body is the site of convergence and interlacing of fibers of several muscles, including the: – Bulbospongiosus – External anal sphincter – Superficial and deep transverse perineal muscles – Smooth and voluntary slips of muscle from the external urethral sphincter, levator ani, and muscular coats of the rectum. Perineal Fasciae a continuity of the abdominal fascia that has two components: – a superficial fatty layer – a deep membranous layer (Colles fascia) In females: – the fatty layer makes up the substance of the labia majora and mons pubis – is continuous anteriorly and superiorly with the Camper fascia In males: – the fatty layer is greatly diminished in the urogenital triangle, – being replaced altogether in the penis and scrotum with smooth (dartos) muscle 1. Superficial perineal pouch – is a potential space between the membranous layer of subcutaneous tissue and the perineal membrane, bounded laterally by the ischiopubic rami In males, the superficial perineal pouch contains the: – Root (bulb and crura) of the penis and associated muscles (ischiocavernosus and bulbospongiosus). – Proximal (bulbous) part of the spongy urethra. – Superficial transverse perineal muscles. – Deep perineal branches of the internal pudendal vessels and pudendal nerves. In females, The superficial perineal pouch contains: – Clitoris and associated muscles (ischiocavernosus). – Bulbs of the vestibule and surrounding muscle (bulbospongiosus). – Greater vestibular glands. – Superficial transverse perineal muscles. – Related vessels and nerves (deep perineal branches of the internal pudendal vessels and pudendal nerves). 2. Deep Perineal Pouch – is bounded: inferiorly by the perineal membrane superiorly by the inferior fascia of the pelvic diaphragm laterally by the inferior portion of the obturator fascia (covering the obturator internus muscle) Contents: – In both sexes, the deep perineal pouch contains – Part of the urethra, centrally. – The inferior part of the external urethral sphincter muscle, above the center of the perineal membrane, surrounding the urethra. – Anterior extensions of the ischioanal fat pads  In males, the deep perineal In females, the deep perineal pouch pouch contains the: contains the: – Intermediate part of the Proximal part of the urethra urethra, the narrowest part of the male urethra. mass of smooth muscle in the place of deep transverse perineal – Deep transverse perineal muscles, muscles on the posterior edge of – Bulbourethral glands, the perineal membrane, embedded within the deep associated with the perineal perineal musculature. body – Dorsal neurovascular Dorsal neurovasculature of the structures of the penis clitoris 1. Male perineum The male perineum includes: – the external genitalia – perineal muscles – and anal canal. – The male external genitalia include: 1. the urethra 1. Membranous urethra 2. Spongy urethra 2. Scrotum 3. Penis 1.SCROTUM is a cutaneous sac consisting of two layers: – heavily pigmented skin – the closely related dartos fascia - smooth muscle fibers (dartos muscle) responsible for the rugose (wrinkled) appearance of the scrotum – As dartos muscle attaches to the skin, its contraction causes the scrotum to wrinkle when cold, reducing scrotal surface area and assisting the cremaster muscles in holding the testes closer to the body, all of which reduces heat loss  The scrotum – is divided internally by a continuation of the dartos fascia, the septum of the scrotum, into right and left compartments. – The septum is demarcated externally by the scrotal raphe a cutaneous ridge marking the line of fusion of the embryonic labioscrotal swellings. – The superficial dartos fascia is devoid of fat: is continuous anteriorly with the membranous layer of subcutaneous tissue of the abdomen (Scarpa fascia) posteriorly with the membranous layer of subcutaneous tissue of  The arterial supply of the scrotumis from: – Posterior scrotal branches of the perineal artery a branch of the internal pudendal artery – Anterior scrotal branches of the deep external pudendal artery: a branch of the femoral artery – Cremasteric artery: a branch of the inferior epigastric artery Scrotal veins accompany the arteries. The lymphatic vessels of the scrotum drain into the superficial inguinal lymph nodes. The nerves of the scrotum include: – branches of the lumbar plexus to the anterolateral surface – branches of the sacral plexus to the posterior and inferior surfaces Genital branch of the genitofemoral nerve (L1, L2): – supplying the anterolateral surface. Anterior scrotal nerves: branches of the ilioinguinal nerve (L1) supplying the anterior surface. Posterior scrotal nerves: branches of the perineal branch of the pudendal nerve (S2-S4) supplying the posterior surface. Perineal branches of the posterior cutaneous nerve of thigh (S2, S3): supplying the posteroinferior surface. Testis are paired ovoid male gonads produce the male germ cells (sperms, or spermatozoa) and male hormones, primarily testosterone are suspended in the scrotum by the spermatic cord the left testis (testicle) usually suspended (hanging) more inferiorly than the right Testis, Why? Covered with two layers: 1. tunica vaginalis 2. tunica albugina – tough fibrous CT layer – that thickens into a ridge on – its internal, posterior aspect as the mediastinum of the testis  The tunica vaginalis is a closed peritoneal sac partially surrounding the testis represents the closed-off distal part of the embryonic processus vaginalis Made up of two layers: 1. Parietal layer: – adjacent to the internal 2. Visceral layer: spermatic fascia covers the surfaces of the testis – is more extensive than except where the testis the visceral layer attaches to the epididymis and – extends superiorly for a spermatic cord short distance into the closely applied to the testis, distal part of the epididymis, and inferior part of spermatic cord the ductus deferens Epididymis – is an elongated structure on the posterior surface of the testis – is formed by minute convolutions of the duct of the epididymis, so tightly compacted that they appear solid consists of the: Head of the epididymis: the superior expanded part that is composed of lobules formed by the coiled ends of 12 -14 efferent ductules. Body of the epididymis: consists of the convoluted duct of the epididymis. Tail of the epididymis: continuous with the ductus deferens, the duct that transports the sperm from the epididymis to the ejaculatory duct for expulsion via the urethra during ejaculation  Blood supply of testis – The long and slender testicular arteries arise from the anterolateral aspect of the abdominal aorta just inferior to the renal arteries – testicular veins: veins emerging from the testis and epididymis form the pampiniform venous plexus, a network of 8 -12 veins a right testicular vein enters the inferior vena cava (IVC) a left testicular vein enters the left renal vein 3. Penis – is the male copulatory organ – conveying the urethra – provides the common outlet for urine and semen – consists of three parts: a root body the glans. – is composed of three cylindrical bodies of erectile cavernous tissue: the paired corpora cavernosa dorsally single corpus spongiosum ventrally 1. The root of the penis – is the attached part of the penis – is located in the SPP – consists of: the two crura, The bulb Two associated muscles – ischiocavernosus – bulbospongiosus muscles – The crura and bulb of the penis contain masses of erectile tissue 2. The body of the penis – is the free pendulous part that is suspended from the pubic symphysis – has no muscles – The penis consists of: thin skin connective tissue blood and lymphatic vessels fascia,and the corpora cavernosa the corpus spongiosum containing the spongy urethra Distally, the corpus spongiosum expands to form the conical glans of the penis, or head of the penis The margin of the glans projects beyond the ends of the corpora cavernosa to form the corona of the glans The corona overhangs an obliquely grooved constriction, the neck of the glans, which separates the glans from the body of the penis. The slit-like opening of the spongy urethra, the external urethral orifice (meatus), is near the tip of the glans.  The skin of the penis – is thin, darkly pigmented relative to adjacent skin – connected to the tunica albuginea by loose connective tissue – At the neck of the glans, the skin and fascia of the penis are prolonged as a double layer of skin, the prepuce (foreskin The frenulum of the prepuce is a median fold that passes from the deep layer of the prepuce to the urethral surface of the glans suspensory ligament of the penis is a condensation of deep fascia that arises from the anterior surface of the pubic symphysis The fundiform ligament of the penis is an irregular mass or condensation of collagen and elastic fibers of the subcutaneous tissue that descends in the midline from the linea alba superior to the pubic symphysi Arterial Supply of the Penis The penis – is supplied mainly by branches of the internal pudendal arteries – Dorsal arteries of the penis: run on each side of the deep dorsal vein in the dorsal groove between the corpora cavernosa supplying the fibrous tissue around the corpora cavernosa, the corpus spongiosum and spongy urethra, and the penile skin – Deep arteries of the penis: pierce the crura proximally and run distally near the center of the corpora cavernosa supplying the erectile tissue in these structures – Arteries of the bulb of the penis: supply the posterior (bulbous) part of the corpus spongiosum and the urethra within it as well as the bulbourethral gland Innervation of the Penis The nerves derive from the S2 to S4 spinal cord segments and spinal ganglia, passing through the pelvic splanchnic and pudendal nerves, respectively Sensory and sympathetic innervation – is provided primarily by the dorsal nerve of the penis, a terminal branch of the pudendal nerve, which arises in the pudendal canal and passes anteriorly into the deep perineal pouch – The penis is richly provided with a variety of sensory nerve endings, especially the glans penis. – Branches of the ilioinguinal nerve supply the skin at the root of the penis – Cavernous nerves, conveying parasympathetic fibers independently from the prostatic nerve plexus, innervate the helicine arteries of the erectile tissue Nerve supply Lymph Drainage The skin of the penis is drained into the medial group of superficial inguinal nodes. The deep structures of the penis are drained into the internal iliac nodes Clinical cases Qs. define the following terms Phimosis Paraphimosis Circumcision Erection Emission Ejaculation 2. Female Perineum – includes the female external genitalia – perineal muscles – and anal canal Female External Genitalia Include: the mons pubis labia majora (enclosing the pudendal cleft) labia minora (enclosing the vestibule) Clitoris bulbs of the vestibule The synonymous terms vulva and greater and lesser vestibular pudendum include all these parts glands the term pudendum is commonly used clinically The vulva serves: – as sensory and erectile tissue for sexual arousal and intercourse. – to direct the flow of urine. – To prevent entry of foreign material into the urogenital tract 1. Mons Pubis is the rounded, fatty eminence anterior to the pubic symphysis, pubic tubercles uperior pubic rami the eminence is formed by a mass of fatty subcutaneous tissue the amount of fat increases at puberty and decreases after menopause after puberty, the mons pubis is covered with coarse pubic hairs 2. Labia Majora – are prominent folds of skin – indirectly provide protection for the urethral and vaginal orifices. – each labium majus largely filled with a finger-like digital process of loose CT containing smooth muscle – is the termination of the round ligament of the uterus – passes infero-posteriorly from the mons pubis toward the anus. lie on the sides of a central depression (a narrow slit when the thighs are adducted), the pudendal cleft  The external aspects of the labia majora: – in the adult are covered with pigmented skin containing many sebaceous glands – are covered with crisp pubic hair The internal aspects of the labia: are smooth, pink, and hairless are thicker anteriorly where they join to form the anterior commissure Posteriorly, in nulliparous women (never having borne children) they merge to form a ridge, the posterior commissure, is the posterior limit of the vulva This commissure usually disappears after the first vaginal birth 3. Labia minora – are rounded folds of fat-free, hairless skin fold – are enclosed in the pudendal cleft – immediately surround the vestibule into which both the external urethral and the vaginal orifices open – have a core of spongy connective tissue containing erectile tissue at their base and many small blood vessels – Anteriorly, the labia minora form two laminae The medial laminae of each side unite as the frenulum of the clitoris The lateral laminae unite anterior to the glans of the clitoris, forming the prepuce (foreskin) of the clitoris In young women, especially virgins, the labia minora are connected posteriorly by a small transverse fold, the frenulum of the labia minora (fourchette) the internal surface of each labium minus consists of thin moist skin it has the pink color typical of mucous membrane and contains many sebaceous glands and sensory nerve endings 4. Clitoris – is an erectile organ located where the labia minora meet anteriorly – consists of a root and a body – are composed of: two crura two corpora cavernosa the glans of the clitoris, which is covered by a prepuce – the body and glans of the clitoris are ≈ 2 cm in length and < 1 cm in Clitoris is highly sensitive and diameter enlarges on tactile stimulation. The glans of the clitoris is the most – It functions solely as an organ of highly innervated part of the clitoris sexual arousal and is densely supplied with sensory endings The vestibule is the space surrounded by the labia minora into is space in which: – the urethra orifice, – Vagina orifice and the ducts of the greater and lesser vestibular glands open – The external urethral orifice is located 2 - 3 cm posteroinferior to the glans of the clitoris and anterior to the vaginal orifice – On each side of the external urethral orifice are the openings of the ducts of the paraurethral glands – The size and appearance of the vaginal orifice vary with the condition of the hymen a thin anular fold of mucous membrane immediately within the vaginal orifice surrounding the lumen The hymen: – After its rupture, only remnants of the hymen, hymenal caruncles (tags), are visible – These remnants demarcate the vagina from the vestibule – The hymen has no established physiological function The bulbs of the vestibule: are paired masses of elongated erectile tissue approximately 3 cm in length lie along the sides of the vaginal orifice, superior or deep to (not within) the labia minora, immediately inferior to the perineal membrane covered inferiorly and laterally by the bulbospongiosus muscles extending along their length The bulbs are homologous with the bulb of the penis of the corpus spongiosum Vestibular Glands The greater vestibular glands – approximately 0.5 cm in diameter – are located on each side of the vestibule, posterolateral to the vaginal orifice and inferior to the perineal membrane; – are in the superficial perineal pouch – The greater vestibular glands (Bartholin glands) are round or oval and are partly overlapped posteriorly by the bulbs of the vestibule, and like the bulbs, are partially surrounded by the bulbospongiosus muscles. – The slender ducts of these glands pass deep to the bulbs of the vestibule – open into the vestibule on each side of the vaginal orifice – These glands secrete mucus into the vestibule during sexual arousal 2. The lesser vestibular glands: – are small glands on each side of the vestibule – open into it between the urethral and the vaginal orifices – These glands secrete mucus into the vestibule, which moistens the labia and vestibule Arterial supply of the vulva – Source: from the external and internal pudendal arteries The internal pudendal artery supplies most of the skin, external genitalia, and perineal muscles. The labial arteries are branches of the internal pudendal artery, as are those of the clitoris Venous and Lymphatic Drainage of the Vulva – The labial veins are tributaries of the internal pudendal veins – Venous engorgement during the excitement phase of the sexual response causes an increase in the size and consistency of the clitoris and the bulbs of the vestibule. – The clitoris becomes turgid, elongating in approximately 10% of women – The vulva contains a rich network of lymphatic vessels that pass laterally to the superficial inguinal lymph nodes – The glans of the clitoris and anterior labia minora may also drain to the deep inguinal nodes or directly to the internal iliac nodes. Innervation of the Vulva The anterior aspect of the vulva (mons pubis, anterior labia) – is supplied by derivatives of the lumbar plexus: the anterior labial nerves, derived from the ilioinguinal nerve, and the genital branch of the genitofemoral nerve The posterior aspect of the vulva – is supplied by derivatives of the sacral plexus: the perineal branch of the posterior cutaneous nerve of the thigh laterally and the pudendal nerve centrally Pudendal nerve block. 1, Transvaginal method. The needle is passed through the vaginal mucous membrane toward the ischial spine. After the needle is passed through the sacrospinous ligament, the anesthetic solution is injected around the pudendal nerve. 2, Perineal method. The ischial tuberosity is palpated subcutaneously through the buttock. The needle is inserted on the medial side of the ischial tuberosity to a depth of about 1 in. (2.5 cm) from the free surface of the tuberosity. The anesthetic is injected around the pudendal nerve Episiotomy  Anal Triangle Contents: 1. Anal canal – is about 1.5 in. (4 cm) long – passes downward and backward from the rectal ampulla to the anus – Except during defecation, its lateral walls are kept in apposition by the levatores ani muscles and the anal sphincters Anal Sphincters – has an involuntary internal sphincter and a voluntary external sphincter. – The internal sphincter is formed from a thickening of the smooth muscle of the circular coat at the upper end of the anal canal is enclosed by a sheath of striped muscle that forms the voluntary external sphincter – The external sphincter can be divided into three parts: A subcutaneous part, which encircles the lower end of the anal canal and has no bony attachments A superficial part, which is attached to the coccyx behind and the perineal body in front A deep part, which encircles the upper end of the anal canal and has no bony attachments Hemorrhoid Ischioanal fossa Thank You!