Prostate gland

Prostate gland: key points

Exocrine gland surrounding urethra in males
Function is to contribute alkaline fluid to semen
Innervated by inferior hypogastric plexus
Lymph from the prostate drains to the internal iliac, external iliac and sacral lymph nodes. Its lymph drainage explains the spread in metastatic disease.
It is located anterior to the rectum and can be palpated through the anterior rectal wall
Normal prostate volume is 20-30 cm³


Wikipedia

Lobes & Zones
The prostate can be divided anatomically into 5 lobes:

Anterior lobe
Median/middle lobe
Posterior lobe
Lateral lobes (Left and Right)

The median lobe has large amounts of glandular tissue so this is the lobe that typically enlarges the most in benign prostatic hypertrophy. When it enlarges it does so in a superior direction and encroaches upon the bladder sphincter. The posterior lobe is the part of the prostate that is palpated on PR examination

Illustration of the lobes of the prostate

The prostate may also be divided into 3 zones:

central zone
peripheral zone
transitional zone

The peripheral zone is important as this is the area where prostate cancers typically start.

Illustration of the zones of the prostate. The peripheral zone is highlighted as this is the area where prostate cancers typically begin. Note this view is from the the opposite side to the sagittal section