Male external genitalia Image

 

 

MALE EXTERNAL GENITALIA

These refer to the reproductive organs that are not placed internally.

In the female they are the vulva and vestibule. In the male they are penis with its contained urethra and the scrotum.

Penis: This is the copulatory organ of the male. It has three main internal structures which are two corpora cavernosa and one corpus spongiosum. The corpora cavernosa are continuous with the crura of penis or clitoris which is its homologue. The corpus spongiosum on the other hand, is continuous with the bulb of penis. The (spongy) urethra transverses the penis, while the does arteries of the penis transverse the corpora cavernosa and their adjoining crura of penis. The penis is drained by superficial and deep dorsal veins of penis while its main arterial supply is from the deep artery of penis which is a branch of the internal pudendal artery.

The penis covered by penile fascia and is attached to the suspensory ligament of the penis which is continuous with the Scarpa’s fascia.

Mechanism of erection in the penis.

This mechanism is dependent on the ability of the spongy tissue (corpora cavernosa) to become engorged with blood, usually arterial blood. This is caused by the contraction of the ischiocavernosus muscle which assists the closure of the drainage pathway of the arteries. Also, it is believed there is a concomitant venoconstriction which helps to keep blood within the spongy tissues of the penis. This mechanism is released after the arousal has passed so that the organ becomes flaccid again. A bone does not exist in penis of man as it does in many animals. This bone is called os penis.

The penis is also responsible for the second stage of ejaculation which involves the emptying of the urethra by the assistance of the bulbospongiosus muscle.

The corpus spongiosum is attached to the glans penis or the head of the penis. The glans is the most sensitive part of the penis, and the penis is the most sensitive part of the whole of the male anatomy. In fact it is  the only part that is sexually arousable by touch. The most arousable part of the glans is its crown. The glans is covered by a prepuce or foreskin. This skin is removed at circumcision in order to permanently expose the glans penis.

Scrotum is that sac that houses the testicles (testes), It has a skin that is wrinkled like the skin of an old man. This is a temperature regulating mechanism. Underneath is the layer of dartos muscle which also helps temperature regulation. The dartos muscle is continuous with Scarpa’s fascia.

Then the 3 layers of the spermatic cord lines the covering of the scrotum as follows.

  • The   most external is the external spermatic fascia, then the intermediate is the cremasteric fascia, while the innermost is the internal spermatic fascia. The tunica vaginalis testis is now found deep to the internal spermatic fascia.

Arteries of the male external genitalia

Penis

Scrotum

Veins of male external genitalia

Penis

  • Deep dorsal vein of penis, which drains into prostatic plexus

Scrotum

  • External pudendal tributaries of femoral vein or great saphenous vein

  • Scrotal tributaries of internal pudendal venae comitantes

  • Cremasteric tributary of inferior epigastric vein

Nerve supply of male external genitalia 

Penis

  • S2-4 nerve through pudendal nerve and pelvic plexuses

  • Dorsal nerve of penis of skin of penis

Scrotum

From L1 nerve to anterior 1/3

  • Ilioinguinal nerve

  • Genital branch of genitofemoral nerve

From S3 nerve to posterior 2/3 of scrotum (2)

  • Posterior scrotal branches of perineal nerve

  • Perineal branch of posterior cutaneous nerve of thigh 

  • Scrotal branches of perineal branch of pudendal nerve (scrotum and penile urethra)

Others

Lymphatics 

  • Embryology

  • Histology

 QUIZ

  There is nothing in anatomy not found in this website

 

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Exposure of male perineum

 

Penis and scrotum

 

Uncircumcised penis with retracted prepuce

Circumcised penis

1 glans penis 2 corona glandis 3 neck 4 shaft 5 root 6 hairline on mons pubis 7 scrotum

Prepuce covering glans in uncircumcised penis

 

Scrotum showing contained testes. Central perineal tendon and anus are below

Anal perineum and  scrotum

Blood supply

1 dorsal artery of penis 2 deep artery of penis 3 perineal artery 4 Internal pudendal artery 5 Inferior rectal artery

Nerve supply

1 pudendal nerve 2 inferior rectal nerve 3 perineal nerve 4 dorsal nerve of penis