Prostate gland

Function

The prostate is a walnut-sized fibromuscular gland encircling the urethra just below the bladder. Its secretions — citrate, zinc, enzymes and PSA — make up 20–30% of semen volume, activating and nourishing sperm on their journey.

It has zones: the peripheral zone (70%, the seat of most cancers, palpable on digital rectal exam), the central zone and the transition zone (where benign enlargement happens). The gland's growth is testosterone-dependent — it withers after castration, flourishes again with therapy.

Blood supply

Inferior vesical and internal pudendal arteries; the prostatic venous plexus drains to the internal iliac veins and communicates with the vertebral venous plexus (the route of prostate cancer's spinal metastases).

Nerve supply

Prostatic plexus — sympathetic from L1 contracts its smooth muscle at ejaculation.

Clinical relevance

Benign prostatic hyperplasia

Transition-zone growth chokes the urethra — hesitancy, weak stream, nocturia; medication relaxes, surgery resects.

Prostate cancer

The commonest male cancer — PSA screening and MRI target the peripheral zone; most men die with it, not of it.

Related conditions

• Enlarged prostate (BPH)
• Prostate cancer