b. corpus spongiosum in midline of urethral surface (facing scrotum)
Each erectile body covered by a fibrous tunic albuginea
Corpora cavernosa
Diverge posteriorly to 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: proximally it forms bulb
Membranous urethra pierces the perineal membrane and enters the bulb from above (so now is called spongy urethra) and terminates at
external urethral meatus (at apex glans)
Root of penis is formed by bulb and crura
Two muscles are associated with erectile bodies
Bulbospongiosus muscle
Ischiocavernosus muscle
Body is surrounded by deep fascia (Buck's fascia), external to tunic albuginea
Skin of penis is connected to deep fascia by loose 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 artery on that side
Lies beneath deep fascia
Supplies skin and glans
Ilioinguinal nerve supplies skin of proximal shaft of penis
Erection controlled by parasympathetic 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 distally within center of corpora cavernosa
Highly coiled branches (helicine arteries) supply erectile tissue
Artery of bulb of penis from internal pudendal artery supplies posterior corpus spongiosum
External pudendal arteries supply skin 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 mainly to superficial inguinal nodesMuscles of the penis
Muscle Proximal attachment Distal
attachmentInnervation ActionBulbospongiosusVentral surface of bulb of penis
Perineal bodyCorpus
spongiosusDeep branch of perineal
nerve from pudendal nerveCompresses bulb of penis
Forces blood into body of
penis during erection
Compresses outflow veins
IschiocavernosusInferior internal surface of ischiopubic
ramus and ischial tuberosityCrus of
penisDeep branch of perineal
nerve from pudendal nerveForces blood into body of
penis during erection
Compresses outflow veins