Clinically, a distinction is made between the left and right lateral lobes, which are separated by the medial (“middle”) sulcus (Latin: central furrow), which can be palpated rectally (“through the rectum“), and the middle lobe, which forms the posterior wall, so to speak, of the prostatic urethra (part of the urethra that passes through the prostate) and often extends into the bladder in benign prostatic hyperplasia (BPH; benign prostatic enlargement).
From a pathophysiological point of view, the classification according to Mc Neal is commonly used today. Here, a distinction is made between:
- Peripheral zone (65% of the prostate volume) → posterolateral (“posterior lateral”) and peripheral from the base (near the bladder) of the prostate to the apex (near the pelvic floor).
- Central zone (25% of the prostate volume) → posterolateral to the base of the prostate.
- Transition zone (5-10% of the prostate volume) → on both sides of the prostatic urethra.
Benign prostatic hyperplasia develops in the transition zone. As it grows, it stretches the peripheral zone and pushes it outward.
Most carcinomas (circa 70%) arise in the peripheral zone.
On both sides of the prostate, dorsolaterally (“towards the back”), lie the two neurovascular bundles (nerve-vascular bundles). In them run nerves and blood vessels for the corpora cavernosa of the penis, they are indispensable for maintaining a natural erection. Their severing in the course of a radical prostatectomy (surgical removal of the entire prostate with its capsule, the adjacent seminal vesicles and the local lymph nodes) leads in practically 100% to loss of erection.
With newer surgical methods, the neurovascular bundles, and thus potency, can be preserved in at least some patients.
