FACTS & HINTS

High-Yield Facts

Clinical Points

Bartholin cyst

Cystic swelling of greater vestibular (Bartholin's) glands

Occurs when gland is infected or duct is blocked

Can enlarge to 4 to 5 cm

Carcinoma of the vulva

Mimics chronic ulcer

Patient presents with pain, a discharging ulcer and occasionallya lump

Metastasis is to inguinal lymph nodes

Greater vestibular gland is origin of most vulvular adenocarcinomas

Childbirth and the perineal body

Overt or occult tearing of perineal bodyresults in permanent weakness of pelvic floor

Can involve tearing of posterior vaginal wall and overlying skin

Slow to heal because of lack of vascular supply

Episiotomydone if tearing of perineum is predicted

Incision usuallymade from posterior vaginal wall through midline to just anterior to anus

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38 Perineum and External Genitalia: Male

STUDYAIMS

At the end of your study, you should be able to:

Outline the general organization of the perineum

Describe the contents of the urogenital and anal triangles

Describe the central perineal tendon and perineal membrane

Outline the fascial layers and spaces of the perineum

Describe the anatomyof the scrotum

Describe the anatomyof the penis

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GUIDE

Pelvis and Perineum: Perineum and External Genitalia: Male

[Plate 361, Male Perineum and External Genitalia (Deeper Dissection)]

Perineum

General organization (Same as female)

Narrow region between superior medial aspects of thigh

With lower limbs abducted in lithotomyposition, becomes a diamond-shaped area

Bounded bypelvic diaphragm superiorlyand superficial fascia and skin inferiorly

Anal canal, urethra, and vagina (females) pass through the perineum

Boundaries:

Anteriorly: Pubic symphysis

Posteriorly: Inferior sacrum and coccyx

Anterolaterally: Ischiopubic rami

Laterally: Ischial tuberosities

Posterolaterally: Sacrotuberous ligaments

Divided into two triangles byimaginaryline between ischial tuberosities

Posteriorlyis anal triangle

Anteriorlyis urogenital triangle

Contents of anal triangle (Same as female)

Anal canal and anus

External and internal anal sphincters

Ischiorectal fossa

Contents of urogenital triangle

Membranous and spongyurethra (males); distal urethra (females)

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Vagina (females)

Proximal erectile bodies of the penis (males) and vulva (females)

Attachment of the scrotum

page 190 page 191

Central perineal tendon (perineal body) (Same as female)

Located at midpoint of the line dividing the urogenital from anal triangles

Mass of collagenous and elastic fibers

Deep to skin

Anterior to anal canal

Posterior to bulb of the penis (male) or vestibule (female)

Site of attachment for

Bulbospongiosus

Superficial transverse perineal muscles

Deep transverse perineal muscles

External anal sphincter

Fascicles of muscle from external sphincter urethrae and levator ani

Perineal membrane

Thin sheet of deep fascia

Runs between the two ischiopubic rami Spans anterior pelvic outlet

Pierced byurethra and ducts of bulbourethral glands

Is attached to perineal bodyat midpoint of posterior margin Thickened anterior margin = transverse perineal ligament Superficial transverse perineal muscles

Lie superficial to (external to) perineal membrane

Extend from ischiopubic ramus on either side along posterior aspect of perineal membrane to attach to the perineal body Deep transverse perineal muscles

Lie deep to (internal to) perineal membrane

Extend from ischiopubic ramus on either side along posterior aspect of perineal membrane to attach to the perineal body Sphincter urethrae (external urethral sphincter)

Lies deep to (internal or superior to) perineal membrane

Circular fibers around membranous part of urethra in males

Anterior to deep transverse perineal muscles

Deep transverse perineal muscles and sphincter urethrae traditionallytermed urogenital diaphragm

Fascia and spaces of the urogenital triangle

page 191 page 192

Superficial fascia of the urogenital triangle has two layers, similar to the abdomen

Superficial fattylayer

Deep membranous layer (Colles' fascia)

Superficial layer replaced in penis and scrotum bydartos layer (smooth or dartos muscle) Membranous layer of superficial fascia

Posteriorlyattached to posterior margin of perineal membrane and perineal body

Laterallyattached to deep fascia (fascia lata) of superior medial thigh

Anteriorlyis continuous with membranous layer of superficial fascia of abdomen (Scarpa's fascia) Deep perineal fascia (Gallaudet's fascia)

Invests ischiocavernosus, bulbospongiosus, and superficial transverse perineal muscles

Fused to suspensoryligament of penis or clitoris Superficial perineal space (pouch)

Between membranous layer of superficial fascia and perineal membrane

Contains in males:

Bulb and crura of penis and associated muscles Proximal spongyurethra

Superficial transverse perineal muscles

Branches of internal pudendal vessels and pudendal nerves Contains in females:

Crura of clitoris and associated muscles Bulbs of vestibule and associated muscles Superficial transverse perineal muscles

Branches of internal pudendal vessels and pudendal nerves Greater vestibular glands

Deep perineal space (pouch)

Lies between perineal membrane and pelvic diaphragm

Ischioanal fossae extend anteriorlyinto this space

Contains: Membranous urethra

External sphincter urethrae

Bulbourethral glands: secrete clear mucous during sexual excitation, ducts descend through perineal membrane and terminate in spongyurethra

Deep transverse perineal muscles

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Vessels and nerves

Male External Genitalia

[Plate 367, Scrotum and Contents]

Scrotum

Sac derived from skin and superficial fascia of abdominal wall Contains testes, epididymis and distal portion spermatic cord

Skin shows midline scrotal raphe = fusion of bilateral labioscrotal swellings in embryo Dartos fascia

Continuation of deep membranous layer of superficial fascia of abdomen

Contains significant smooth muscle = dartos muscle

Extends inward, forming scrotal septum, separating right and left halves

Deep to dartos, tunics of spermatic cord (external spermatic, cremasteric and internal spermatic fascia form a fused layer around and external to tunica vaginalis

Supplied byexternal pudendal arteries and veins Lymphatics drain to superficial inguinal lymph nodes Innervated by

Anteriorly, ilioinguinal nerve and genital branch of genitofemoral

Posteriorly, posterior scrotal nerves (terminal branches of the pudendal) and perineal branches of the posterior femoral cutaneous nerves

Penis

page 192 page 193

Male organ of copulation

Composed of a body (shaft), root and glans Body is

Anchored in superficial perineal space (pouch) and attached to perineal membrane

Contains three cylindrical masses of erectile tissue

a. paired corpora cavernosa in parallel on dorsal surface

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b. corpus spongiosum in midline of urethral surface (facing scrotum) Each erectile bodycovered bya fibrous tunic albuginea

Corpora cavernosa

Diverge posteriorlyto form the crura of the penis

Each crus attaches to the inferior surface of corresponding ischiopubic ramus, anterior to ischial tuberosity Glans of the penis is the distal expansion of the corpus spongiosum: proximallyit forms bulb

Membranous urethra pierces the perineal membrane and enters the bulb from above (so now is called spongyurethra) and terminates at external urethral meatus (at apexglans)

Root of penis is formed bybulb and crura

Two muscles are associated with erectile bodies

Bulbospongiosus muscle

Ischiocavernosus muscle

Bodyis surrounded bydeep fascia (Buck's fascia), external to tunic albuginea Skin of penis is connected to deep fascia byloose areolar connective tissue

At neck of the glans, the skin and connective tissue of the penis extends and a double-layered fold, the prepuce or foreskin Vessels and nerves run on dorsum of penis

Between skin and deep fascia

Between deep fascia and tunica albuginea Innervation

Dorsal nerve of the penis from the pudendal nerve

Passes the length of the penis lateral to the dorsal arteryon that side Lies beneath deep fascia

Supplies skin and glans

Ilioinguinal nerve supplies skin of proximal shaft of penis

Erection controlled byparasympathetic nerves (pelvic splanchnic nerves), which relaxes smooth muscle in coiled arteries of penis supplying erectile bodies

Arterial supply

Dorsal arteries of penis from internal pudendal arteries run on either side of deep dorsal vein beneath deep fascia

Deep arteries from internal pudendal arteries Run distallywithin center of corpora cavernosa

Highlycoiled branches (helicine arteries) supplyerectile tissue

Arteryof bulb of penis from internal pudendal arterysupplies posterior corpus spongiosum

External pudendal arteries supplyskin of penis (branch of femoral artery). Venous drainage

Deep dorsal vein of penis receives blood from venous plexus

Drains to prostatic venous plexus and then to internal iliac/internal pudendal veins. Superficial dorsal vein of penis drains to superficial external pudendal vein

Lymphatic drainage mainlyto superficial inguinal nodes

Muscles of the penis

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