Prostate
The prostate gland is part of the male reproductive system and is the largest male accessory gland. It typically weighs between 20-40 grams with an average size of 3 x 4 x 2 cm. The prostate is comprised of 70% glandular tissue and 30% fibromuscular or stromal tissue 1-3 and provides ~30% of the volume of seminal fluid.
On this page:
Gross anatomy
The prostate gland is an inverted pyramid that surrounds the proximal urethra, which traverses the prostate close to its anterior surface. The base of the prostate is in continuity with the bladder. It ends inferiorly at the apex at the urogenital diaphragm 1-3.
The anterior surface forms the posterior limit of the retropubic space. The prostate is connected to the pubic bone by the puboprostatic ligaments 1. Its inferolateral surface rests on the levator ani fascia 3. Its triangular and flat posterior surface is anterior to the rectum and has a vertical median groove, which is palpable via a digital rectal exam (DRE). It is separated from the rectum by the rectovesical fascia (Denonvilliers’ fascia).
The seminal vesicles are superior and posterior to the prostate gland. Their ejaculatory ducts pierce the posterior surface of the prostate below the bladder 1-3 and drain into the prostatic urethra on the verumontanum.
The prostate gland lacks a true capsule and the so-called prostate capsule (often confusingly called the true capsule, especially in older texts) is a pseudocapsule formed from fibromuscular tissue surrounding 3 distinct layers of fascia; the anterior, lateral, and posterior fasciae. Anteriorly and apically this pseudocapsule is deficient. Laterally the fascia fuses with the levator fascia. The prostatic venous plexus (Santorini's plexus) lies between, and passes through, the pseudocapsule and fascia 1-3,9-11.
Neurovascular bundles travel posterolaterally at 5 and 7 o'clock and give off branches into the prostate at the apex and base 5.
Zonal anatomy
The prostate is comprised of three distinct zones with different embryologic origins:
- peripheral zone
- central zone
- transition zone
The large cup-shaped peripheral zone (PZ) encompasses the central and transition zones and accounts for approximately 70% of the total prostate volume in a young adult. The peripheral zone surrounds the distal prostatic urethra at the apex of the prostate and extends posterolaterally to the base. The PZ is deficient anteriorly where it is replaced by the anterior fibromuscular stroma (AFMS). Most prostatic tumors occur in the PZ.
The small wedge-shaped central zone (CZ) constitutes up 25% of the prostate volume and contains the ejaculatory ducts. It is posterior to the prostatic urethra and forms the base of the prostate.
The smaller transition zone (TZ) makes up the remaining 5% of the prostatic volume. It is predominantly anterolateral to the prostatic urethra 2-4. The transition zone is occasionally written incorrectly as the transitional zone. Benign prostatic hypertrophy occurs in the TZ.
Some radiologists and urologists refer to the central gland (CG) which consists of both the central and transition zones.
Relations
- anteriorly: pubic symphysis
- posteriorly: rectum
- superiorly: bladder
- inferiorly: urogenital membrane
- laterally: prostatic venous plexus and levator ani
Arterial supply
- prostatic branch of inferior vesical artery, a branch of the anterior division of the internal iliac artery
- sometimes supplied by the middle rectal arteries
Venous drainage
- prostatic venous plexus in communication with the pudendal plexus to the deep dorsal vein (to the internal iliac vein) with some communication to the Batson vertebral venous plexus 2,3,5
Lymphatic drainage
- drainage mainly to obturator and internal iliac nodes
- some drainage to external iliac, presacral and para-aortic nodes 1-4
Innervation
- parasympathetic (S2-S4) and sympathetic (L1-L2) pelvic nerve plexus
Radiographic features
Ultrasound
- best assessed with transrectal ultrasound
- some zonal anatomy distinguishable
- outer gland (central and peripheral zones) - uniform low echogenicity but usually more echogenic than the inner gland 6,7
- 30 mL is a commonly used upper limit for normal volume
CT
- poor for assessment of prostate zonal anatomy and pathology
- with adjusted window settings
- central zone appears hyperdense between 40-60 HU
- peripheral zone appears hypodense between 10-25 HU
- useful for nodal and metastatic staging 4,6,8
MRI
- preferred imaging modality
- T1: homogenous intermediate signal intensity
-
T2
- anterior fibromuscular stroma is low T1W and T2W signal
- peripheral zone is high T2W signal, similar to or greater than adjacent fat
- there are age-related decreases in T2W signal
- central and transition zones are lower T2W signal than peripheral zone
- "capsule" is a thin rim of low signal intensity
- distal urethra is a low intensity ring 4,5
Development
- central zone: Wolffian duct
- transition zone: urogenital sinus
- peripheral zone: urogenital sinus 3
Related pathology
Related Radiopaedia articles
Anatomy: Abdominopelvic
- skeleton of the abdomen and pelvis
- muscles of the abdomen and pelvis
- spaces of the abdomen and pelvis
- anterior abdominal wall
- posterior abdominal wall
-
abdominal cavity
-
peritoneum
- peritoneal ligaments
- mesentery
-
peritoneal spaces
-
supramesocolic space
-
right supramesocolic space
- right subphrenic space
-
right subhepatic space
- anterior right subhepatic space
- posterior right subhepatic space (Morison pouch)
-
lesser sac
- epiploic foramen (of Winslow)
- left supramesocolic space (left perihepatic space)
-
right supramesocolic space
- inframesocolic space
-
supramesocolic space
- inguinal canal (mnemonic)
- Hesselbach triangle
- umbilical folds
- retroperitoneum
-
peritoneum
- pelvic cavity
- perineum
- abdominal and pelvic viscera
- gastrointestinal tract
- spleen
- hepatobiliary system
-
endocrine system
-
adrenal gland
- adrenal vessels
- chromaffin cells
- variants
- pancreas
- organs of Zuckerkandl
-
adrenal gland
-
urinary system
-
kidney
- renal pelvis
- renal sinus
- avascular plane of Brodel
-
variants
- number
- fusion
- location
- shape
- ureter
- urinary bladder
- urethra
- embryology
-
kidney
- male reproductive system
-
female reproductive system
- vulva
- vagina
- uterus
- uterine tubes
- ovaries
- broad ligament (mnemonic)
- variant anatomy
- embryology
- blood supply of the abdomen and pelvis
- arteries
-
abdominal aorta
- inferior phrenic artery
- celiac artery
- superior mesenteric artery
- middle suprarenal artery
- renal artery (variant anatomy)
- gonadal artery (ovarian artery | testicular artery)
- inferior mesenteric artery
- lumbar arteries
- median sacral artery
-
common iliac artery
- external iliac artery
-
internal iliac artery (mnemonic)
- anterior division
- posterior division (mnemonic)
- variant anatomy
-
abdominal aorta
- portal venous system
- veins
- anastomoses
- arterio-arterial anastomoses
- portal-systemic venous collateral pathways
- watershed areas
- arteries
- lymphatics
- innervation of the abdomen and pelvis
- lumbar plexus
-
sacral plexus
- lumbosacral trunk
- sciatic nerve
- superior gluteal nerve
- inferior gluteal nerve
- nerve to piriformis
- perforating cutaneous nerve
- posterior femoral cutaneous nerve
- parasympathetic pelvic splanchnic nerves
- pudendal nerve
- nerve to quadratus femoris and inferior gemellus
- nerve to internal obturator and superior gemellus
Prostate pathology
-
prostate gland
- prostate tumors
- infections of the prostate
-
prostatitis
- acute bacterial prostatitis
-
chronic prostatitis
- chronic bacterial prostatitis
- chronic prostatitis and chronic pelvic pain syndrome (CPPS)
- asymptomatic inflammatory prostatitis
- granulomatous prostatitis
- emphysematous prostatitis
- prostatic abscess
-
prostatitis
- benign prostatic hypertrophy
- cystic lesions of the prostate
- prostatic calcification
- prostatic infarction
Unable to process the form. Check for errors and try again.