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Gross anatomy of Male & Female External Genitalia MBBS Yr. II

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1 Gross anatomy of Male & Female External Genitalia MBBS Yr. II
Dr. Wai Wai Kyi March 2012

2 Gross anatomy of Male & Female External Genitalia
Objectives The objective of the lecture is to discuss the gross and surgical anatomy of the male external genitalia. Learning Outcomes At the end of the lecture, students should be able to: Explain the coverings, blood supply, nerve supply, lymphatic drainage and surgical anatomy of scrotum. Describe the parts, blood supply, nerve supply and lymphatic drainage of penis. Explain the female external genitalia or pudendum.

3 External female genitalia

4 Mons pubis (L. mountain) A fatty pad covered with
External female genitalia (vulva or pudendum) It include the: â–ª Mons pubis â–ª Labia majora (large lips) â–ª Labia minora (small lips) â–ª Vestibule of the vagina â–ª Clitoris Mons pubis (L. mountain) A fatty pad covered with skin and pubic hair.The amount of fat increases during puberty and decreases after menopause.

5 Labia majora The soft, fatty, skin-covered tissue that encloses and protects the rest of the vulva. Unite to form mons pubis, L majora & minora; swell with blood during sexual arousal. Labia minora - hairless skin folds The thinner more delicate folds of skin surrounding the inner components of the vulva. They produce secretions from oil glands to keep the vaginal opening moist; contain many nerve endings. Toward the front, the lips join forming the clitoral hood, which protects the clitoris.

6 â–ª Vestibule of the vagina The space between the
labia minora; consists of ◌ clitoris ◌ urethral orifice ◌ vaginal introitus/opening below the urethral orifice ◌ paraurethral glands; ducts of greater vestibular glands are in its floor. Clitoris - female erectile structure, homologous with the penis, highly sensitive organ. Clinical perineum Region between vagina and anus

7 Greater vestibular glands (Bartholin's glands)
They are located on each side of the vestibule of the vagina, posterolateral to the vaginal orifice. Slender ducts open into the vestibule of the vagina on each side of the vaginal orifice. The greater vestibular glands are homologous with the bulbourethral glands/ Cowper’s gland in the male. It secrete a small amount of lubricating fluid. Lesser vestibular glands These are small glands on each side of the vestibule of the vagina. They open into it between the urethral and vaginal orifices.

8 Perineum It is the region inferior to the pelvic diaphragm. A diamond- shaped area and is bounded anteriorly by the symphysis pubis, posteriorly by the tip of the coccyx and laterally by the ischial tuberosities. A transverse line drawn between the ischial tuberosities divides the perineum into an anterior urogenital triangle that contains the extermal genitalia and a posterior anal triangle that contains the anus & the two ischiorectal fossae. Urogenital triangle Ischial tuberosity Anal triangle

9 Pelvic cavity (superior to PD) Pelvic diaphragm
Perineum (inferior to PD) Iliac crest Greater pelvis Lesser pelvis Pelvic brim Pelvic diaphragm Ischial tuberosity Perineum

10 Comparative Anatomy: Clitoris and Penis

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13 Pudental nerve S2-4 – provides the principal innervation of the
perineum. Pudental nerve block – Anesthetic, administered near the ischial spine, would block the pudendal nerve. It blocks the pain for the S2 to S4 dermatomes (most of the perineum and lower ¼ of the vagina).

14 External female genitalia

15 The arterial supply of the female external genitalia
Rich arterial supply to the vulva is from two external pudendal arteries arises from femoral artery and one internal pudendal artery on each side. The internal pudendal artery arises from internal iliac artery supplies the skin, sex organs, and the perineal muscles. The labial arteries are branches of the internal pudendal artery, as are the dorsal and deep arteries of the clitoris. Venous drainage of the female external genitalia The labial veins are tributaries of the internal pudendal veins and venae comitantes of the internal pudendal artery. Lymph drainage of the female external genitalia The vulva contains a very rich network of lymphatic channels. Most lymph vessels pass to the superficial inguinal lymph nodes and deep inguinal nodes.

16 Innervation of the female external genitalia
Ilioinguinal nerve Genital branch of genitofemoral nerve; Perineal branch of femoral cutaneous nerve Perineal nerve of pudendal nerve

17 Applied anatomy Episiotomy An incision made in the tissue between the vaginal opening and anus (perineum) to prevent tearing during childbirth. Types of episiotomies Medio-lateral incision which curves away from the rectal area Midline incision

18 Male external genital organs

19 Male reproductive anatomy
External: - penis - scrotum Internal: - gonads - accessory sex glands and ducts.

20 Male External Genital Organs
The Scrotum The scrotum develops from an out-pouching of the skin of the anterior abdominal wall. The scrotum is a loose cutaneous fibromuscular sac that is situated posteroinferior to the penis and inferior to the pubic symphysis. Its bilateral formation is indicated by the midline scrotal raphe. This continues on the ventral surface of the penis as the penile raphe and posteriorly along the median line of the perineum to the anus as the perineal raphe.

21 Layers of scrotum skin dartos muscle external spermatic fascia cremastric fascia internal spermatic fascia peritoneum, tunica vaginalis Coverings of spermatic cord (Spermatic fascia) 3 concentric layers of fascia derived from layers of anterior abdominal wall: • external spermatic fascia - derived from EO • cremasteric fascia - derived from IO • internal spermatic fascia- derived from fascia transversalis attached to margins of deep inguinal ring.

22 Structure of scrotum The wall of the scrotum is made up of numerous layers.These are: Skin: Thin, wrinkled and pigmented. It forms a single pouch around the entire surface. In the middle, there is a slightly raised ridge, which indicates the fusion of the two lateral labioscrotal swellings. In females, the lateral swellings remain separate and form the labia majora. Superficial fascia: The superficial fascia of scrotum is continuous with the fatty and membranous layers of fascia of anterior abdominal wall. The fatty layer in this region is replaced by a smooth muscle known as dartos muscle, which is innervated by sympathetic nerve fibers. It is primarily responsible for wrinkling of the skin. The membranous layer of fascia in the scrotal region is known as Colle’s fascia. It is continuous in front with the Scarpa’s fascia (membranous layer of fascia of anterior abdominal wall). Both layers of superficial fascia contribute to the median partition, separates the testes from each other.

23 Descent of testis through inguinal canal to scrotum
Transversalis fascia - deep ring/internal spermatic fascia Peritoneum forming processus vaginalis/tunica vaginalis testis Transversus abdominis Internal oblique - cremaster muscle External oblique - superficial ring/ external spermatic fascia Gubernaculum

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26 Arterial supply of the scrotum
The external pudendal arteries supply the anterior aspect of the scrotum. The internal pudendal arteries supply its posterior aspect. It also receives branches from the testicular and cremasteric arteries. Venous drainage of the scrotum The scrotal veins accompany the arteries and join the external pudendal veins. Innervation of the scrotum Its anterior part is supplied by the ilioinguinal nerve. Its posterior part is supplied by the medial and lateral scrotal branches of the perineal branch of pudendal nerve and the perineal branch of the posterior femoral cutaneous nerve.

27 Lymphatic drainage of the scrotum
The lymph vessels from the scrotum drain into the superficial inguinal lymph nodes. Lymph from testes and epididymis (structures contained within scrotum) drains into the para-aortic lymph nodes at the level of first lumbar vertebra. This is because during development, testes migrate from high up on the posterior abdominal wall.

28 Structures of spermatic cord • vas deferens (cordlike structure that can be palpated between fingers and thumb in the upper part of the scrotum). • artery of the ductus deferens (from the inferior vesical artery ) • testicular artery (from aorta) • testicular veins (pampiniform plexus) • testicular lymph vessels • autonomic nerves • remains of processus vaginalis • cremasteric artery (from the inferior epigastric artery). • genital branch of genitofemoral nerve (supplies cremaster muscle)

29 Descent of testes Begin development near kidney Gubernaculum (cordlike structure containing muscle) extends from gonad to abdominopelvic floor - it shortens, guides testes to scrotum Vaginal process - Peritoneum develops fold; extends into scrotum - Create inguinal canal, pass through abdominal wall Descent begins in weeks 6-10, finished by 28 - 3% born with undescended testes (cryptorchidism) - Location outside pelvic cavity essential for low temperatures needed for sperm production.

30 The Penis

31 Fascia and Ligaments of Penis
Fundiform lig – from linea alba & membranous layer of sup fascia of abdomen (Scarpa's fascia). Suspensory Ligament This is a condensation of deep fascia in the form of a thick, triangular, fibroelastic band. It arises from the anterior surface of the pubic symphysis and passes inferiorly. It splits to form a sling, which is attached to the deep fascia of the penis at the junction of its fixed and mobile parts, lies deep to fundiform lig. Deep fascia of penis (Buck’s fascia) – continuation of deep perineal fascia, continuous with fascia covering ext oblique m & rectus sheath. Tunica albuginea – dense fibrous layer that envelopes both corpora cavernosa & corpus spongiosum.

32 Tunica vaginalis – double serous membrane, peritoneal sac at
the end of process vaginalis. covers front and sides of testis and epididymis closed sac derived from abd. peritoneum, forming innermost layer of scrotum parietal layer = adjacent to int spermatic fascia visceral layer = adherent to testis & epididymis

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34 Parietal pelvic fascia Visceral pelvic fascia Camper’s fascia
Peritoneum Skin Transversalis fascia Parietal pelvic fascia Visceral pelvic fascia Camper’s fascia Scapa’s fascia Deep abdominal fascia Seminal vesicle Fundiform ligament Suspensory ligament Perineal membrane Superficial penile fascia Buck’s fascia Buck’s fascia (a layer of deep fascia covering the penis) Deep muscular perineal membrane Scrotum Colle’s fascia 34 Camper’s fascia 34

35 Male reproductive system

36 Penis Consists of three masses of vascular erectile tissue, the paired corpus cavernosa & midline corpus spongiosum which are bounded by tunica albuginea. Root This is its attached portion, consists of: - Crus of penis = covered by ischiocavernosus muscle - Bulb of penis = covered by bulbospongiosus muscle Body (shaft) Free part and contains: 2 corpus cavernosa 1 corpus spongiosum

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38 Penis (Cont.) The spongy urethra is within the corpus spongiosum Glans penis - formed by the terminal part of corpus spongiosum & is covered by free fold of skin, the prepuce. The frenulum of the prepuce is a median vertical fold from the deep surface of prepuce. Has a prominent margin of the glans penis, the corona (L. crown). The slit-like opening of the spongy urethra is near the tip of the glans penis, the external urethral orifice (meatus); a terminal dilated part of the urethra in the glans, the fossa navicularis.

39 Anatomy of penis

40 Boundaries of Male Perineum

41 Male reproductive structures

42 Arterial Supply of the Penis
The arteries to the penis are: Artery to the bulb, which enters on each side. The dorsal and deep arteries are branches of the internal pudendal arteries. The deep arteries are the principal vessels that supply the cavernous spaces (erectile tissue) in the three corpora. They give off numerous branches that open directly into these spaces. When the penis is flaccid, these arterial branches are coiled; hence, they are called helicine arteries (G. helix, a coil).

43 Venous Drainage of the Penis
Blood from the cavernous spaces is drained by a venous plexus that joins the deep dorsal vein located in the deep fascia, drain into the prostatic & pelvic venous plexuses Blood from the superficial coverings of the penis drain into the superficial dorsal vein and then into the superficial external pudendal vein. Lymphatic Drainage of the Penis From most of the penis, lymph drains into the superficial inguinal lymph nodes. Vessels from the glans penis drain into the deep inguinal lymph nodes.

44 Innervation of the Penis
The dorsal nerve of the penis is one of the two terminal branches of the pudendal nerve. The dorsal nerve arises in the pudendal canal. It supplies both the skin and glans penis. The penis is richly innervated with sensory nerve endings, especially the glans. The cavernous nerves from the inferior hypogastric plexus pass through the urogenital diaphragm to reach the penis. The skin covering the root of the penis is supplied by the ilioinguinal nerve and the posterior scrotal branches of the perineal nerve.

45 Testes Arteries: The testicular arteries arise from the abdominal aorta just inferior to the renal arteries. Veins: the testicular veins emerge from the testis and epididymis and join to form a venous network, the pampiniform plexus. The cooler venous bood within the pampiniform plexus absorbs heat from the arterial blood, providing a thermoregulatory system for the testis. The L testicular vein empties into the L renal vein. The R enters the IVC. Lymphatics: drainage is to the lumbar and pre-aortic lymph nodes. Nerves: The autonomic nerves of the testis arise as the testicular plexus of nerves on the testicular artery, which contains vagal parasympathetic fibers and sympathetic visceral afferent fibers from T7. They share their embryologic origin with the kidney.

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47 Urinary extravasation
Applied anatomy (Male external genitalia) Rupture of spongy urethra is common in straddle injury that results in extraperitoneal extravasation of urine within the superficial perineal pouch and extending into the scrotal, penile, and fatty layer of subcutaneous connective of the lower anterior abdominal wall areas. Urinary extravasation 47

48 â–  Urine does not extend into the thigh region or anal triangle because
Rupture of spongy urethra (Cont.) ■ Urine does not extend into the thigh region or anal triangle because ♦ superficial fascia of the perinium (Colle’s fascia), blends with fascia lata. ♦ superficial & deep layers of the perineal fascia are continuous with each other around the superficial transverse perineal muscle Colles’fascia  superficial perineal fascia Deep perineal fascia invests the ischiocavernosus, bulbospongiosus and superficial transverse perineal muscle. Urogenital triangle Anal triangle 48

49 Rupture of spongy urethra (Cont.)
Any fluid (blood, urine, or pus) that is within the superficial pouch will be limited by Colle’s fascia and its attachments. If the deep fascia (Thick fibrous envelope) of Buck is not torn, extravasation is confined to the penis; however if the trauma tears the deep fascia of Buck, then extravasation of urine occurs within the superficial perineal space. 49

50 c The superficial perineal pouch is a compartment bounded by the superficial perineal fascia (Colles’ fascia), the perineal membrane (inferior fascia of the urogenital diaphragm), and the ischiopubic ramus Inf. layer of urogenital diaphragm Aponeurosis of external oblique 50

51 Membranous layer of superficial fascia (Scarpa’s fascia)
Fatty layer of superficial fascia (Camper’s fascia) Membranous layer of superficial fascia (Scarpa’s fascia) Urogenital diaphragm Anal canal Deep perineal pouch Perineal body Fat of ischiorectal fossa Superficial perineal pouch Superior fascial layer of urogenital diaphragm Colle’s fascia Dartos muscle Inferior fascial layer of urogenital diaphragm (perineal membrane) Scrotum 51

52 Applied anatomy (Male external genitalia) Testicular torsion Testicular torsion is a urologic emergency. Prompt diagnosis and early treatment is essential as time is critical for testicular salvage. Torsion is more common in children but can occur in post pubertal males. The testicular torsions can result from anatomic defects, anomalous suspension of the testes in the scrotum and an undescended testicle. Undescended testes (Cryptorchidism) Prevents normal sperm development, prone to infertility and testicular cancer.

53 Hydrocele A fluid-filled cavity of eiter testis or spermatic cord, where peritoneal fluid passes into a patent processus vaginalis. Normal: The fluid around the testicles is absorbed. Noncommunicating hydrocele: The fluid stays around the testicles and is not absorbed. Communicating hydrocele: The fluid flows back and forth between the scrotum and the abdomen, the processus vaginalis is still open Hydrocele of the cord: The fluid is located in the spermatic cord, between the scrotum and the abdomen.

54 Applied anatomy (Male external genitalia) Cont.
Varicocele A varicocele is a collection of tortuous and dilated veins within the pampiniform plexus of the spermatic cord and can result in infertility secondary to decreased sperm motility and count. They are due to incompetent valves in the testicular vein. Smegma- accumulation of secretions on the penile glans from glands of foreskin, supports bacterial growth, such as E. coli. Epididymitis Orchitis Orchitis is an acute infection of the testicle usually following epididymitis.

55 Vasectomy Ductus deferens (vas deferens) are cut and ends are closed; sperm continue to be produced, but can no longer exit the body. Phimosis Tightening of the foreskin which may cause it not to be able to retract and may interfere with urination. Treatment is usually circumcision (surgical procedure involving removal of the prepuce).

56 foreskin glans penis urethral opening sutures shaft corona
Circumcision foreskin glans penis urethral opening sutures shaft corona

57 Hypospadias & Epispadias
The urethral opening appears either on the underside or upper side of the penis but not at the tip Treatment – reconstructive surgery

58 Pudendal canal Contains pudendal artery, pudendal vein, and pudendal nerve. It runs along the lateral wall of the ischiorectal fossae, just medial to the obturator internus muscle and along the medial surface of the ischial tuberosity. It then runs anteriorly along the medial aspect of the ischiopubic ramus

59 Arteries of the external genitalia
Internal pudendal artery branches (Arise from internal iliac artery): Inferior rectal artery Perineal a Artery to the bulb Urethral artery Dorsal arteries of penis &clitoris Deep artery of the penis &clitoris External pudendal (br.of femoral artery)- Skin above pubis, penis & scrotum or labium majus

60 Any Questions ? THANK YOU


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