Penis

Penis is the male external reproductive organ that has a copulative and an additional urinal role. It is composed of three columns of erectile tissue and can be divided into two parts: root and body.

Root of penis:

Root of penis is made of three masses of erectile tissue: bulb and right and left crura.

Bulb:

The bulb is situated in the midline and is attached to the undersurface of the urogenital diaphragm. It is traversed dorsally by the urethra and is covered on its outer surface by the bulbospongiosus muscle. The bulb continues forward into the body of the penis and forms the corpus spongiosum

Crura:

Both right and left crura are attached to the side of the respective pubic arch and are covered on their outer surface by the ischiocavernosus muscle. They converge anteriorly in the body of penis and come to lie side by side forming the corpora cavernosa.

Body of penis:

Body of penis is composed of three cylinders of erectile tissue that are collectively enclosed in a tubular sheath of fascia known as Buck’s fascia. The cylinders of erectile tissue are two dorsal corpora cavernosa and a single ventral corpus spongiosum.

The body of the penis is supported by two condensations of deep fascia, which extend downward from linea alba (abdomen) and symphysis pubis (pelvis). These condensations are attached to the Buck’s fascia of penis.

Glans penis:

At the distal extremity of the body, the corpus spongiosum expands to form the glans penis that covers the distal ends of both corpora cavernosa. On the tip of the glans, there is a slit-like orifice of urethra, known as the external urethral meatus.

Prepuce (Foreskin):

It is a hood-like fold of skin that covers the glans, to which it is connected just below the urethral orifice by a fold called the frenulum.

Blood supply:

  • Arterial supply to penis is provided by branches of internal pudendal artery. These branches include:
    • Deep arteries of penis: They supply the corpora cavernosa
    • Artery of the bulb: It supplies the corpus spongiosum
    • Dorsal artery of penis: It runs on the dorsum of the penis to the glans where it divides into branches, which supply the glans and prepuce.
  • Veins of penis, most conspicuous of which are the dorsal veins, drain into the internal pudendal veins.

Lymph drainage:

  • Lymph from the skin of penis is drained into the medial group of superficial inguinal lymph nodes.
  • Lymph from deep structures of penis is drained into the internal iliac lymph nodes.

Nerve supply:

Nerve fibers to penis are provided by the inferior hypogastric plexus and the pudendal nerve.