Prostate Anatomy

Question 1

What is the prostate?

Answer 1

A fibromuscular glandular organ, known as a compound tubuloaveolar exocrine gland.

Question 2

What is the main function of the prostate gland?

Answer 2

To store and secrete a fluid that nourishes the sperm. It contributes to sperm motility and viability.

Question 3

What percentage of semen is formed by the fluid secreted by the prostate gland?

Answer 3

25%

Question 4

What substances does the fluid contain? What do they do?

Answer 4

Citric acid
Proteolytic enzymes (inc Prostate Specific Antigen - PSA)
Pepsinogen
Lysozyme
Amylase
Hyaluronidase
Break down the clotting proteins from the seminal vesicles

Question 5

Where is the prostate located? (inf/suf/ant/post)

Answer 5

Inferiorly and posteriorly to the bladder
Anterior to the rectum

Question 6

What part of the male anatomy does the prostate surround?

Answer 6

Prostatic urethra

Question 7

What shape and size is the prostate?

Answer 7

Resembles a walnut in shape and size (approx 3cm long and 4cm wide)

Question 8

What are the 2 main parts of the prostate?

Answer 8

Base and apex

Question 9

Where is the base of the prostate?

Answer 9

Superior part of the gland which lies below the bladder

Question 10

What is the apex of the prostate?

Answer 10

Inferior part of the gland

Question 11

What is the function of the vas deferens?

Answer 11

Carries the sperm from the epididymis to the ejaculatory gland

Question 12

Where do the seminal vesicles lie and what is their function?

Answer 12

The seminal vesicles lie on the posterior surface of the bladder and secrete thick fluid into the ejaculatory duct, which mixes with the sperm

Question 13

What do the two ejactulatory ducts pierce?

Answer 13

The upperposterior surface of the prostate, and openinto the prostatic urethra

Question 14

Where are the bulbourethal glands located?

Answer 14

Located within the external urethral sphincter. Secrete amucus-like fluid into the urethra during sexual arousal.

Question 15

What is the prostate surrounded by?

Answer 15

Afibrous prostatic capsule, which in turn is enclosed in a fibrous sheath (prostatic fascia)

Question 16

What sits within the fascial shell of the prostate?

Answer 16

The prostatic plexus of nerves and veins, a continuation of the lower part of the pelvic plexus, this innervates the urethra and penis

Question 17

Why is nerve-sparing crucial?

Answer 17

It is crucial to preventerectile dysfunction and bladder incontinence issues

Question 18

Where is the prostate located anteriorly?

Answer 18

Separated from the symphisis pubisby extraperitoneal fat in the retropubic space (known as the cave of Retzius)

Question 19

Where is the prostate located posteriorly?

Answer 19

The posterior aspect of the prostate is closely related to the anterior surface of the rectal ampulla and is separated from it by the rectovesical septum

Question 20

Where is the prostate located laterally?

Answer 20

The prostate is held by the anterior fibres of the levator ani muscle, which runs posteriorly from the pubis.

Question 21

How many lobes does the prostate have?

Answer 21

5

Question 22

What are the 5 lobes of the prostate?

Answer 22

Right and left lateral lobes(rich in glands)
Anterior lobe (NO glandular tissue)
Median (middle) lobe (rich in glands)
Posterior lobe (rich in glands)

Question 23

For clinical purposes in staging prostate cancer, how many lobes does the prostate have?

Answer 23

2

Question 24

How many zones does the prostate have?

Answer 24

4

Question 25

What are the 4 zones of the prostate?

Answer 25

Anterior zone (fibromuscular stroma) Central zone Transition zone Peripheral zone

Question 26

Anterior zone (fibromuscular stroma)

Answer 26

Mainly muscle tissue

Question 27

Central zone

Answer 27

Surrounds the ejaculatory ducts

Question 28

Transition zone

Answer 28

Surrounds the urethra – this glands of the TZ are often those affected by Benign Prostatic Hyperplasia

Question 29

Peripheral zone

Answer 29

Makes up the main body of the gland (~65%). The ducts of the PZ empty prostatic fluid into the prostatic urethra. ~70% of cancer cases arise in the PZ

Question 30

How long is the prostatic urethra?

Answer 30

3cm long

Question 31

Where does the prostatic urethra begin?

Answer 31

At the neck of the bladder

Question 32

What does the prostatic urethra pass through?

Answer 32

Passes through the prostate from the base to the apex, and becomes continuous with the 'membraneous urethra'

Question 33

What arteries supply the prostate with blood?

Answer 33

Inferior vesical artery, pudendal artery and the middle rectal artery, which themselves are supplied by the internal iliac artery

Question 34

What veins take away the blood from the prostate?

Answer 34

Blood is received from the dorsal vein of the penis and many vesical veins that drain to the internal iliac veins. The veins form the prostatic venous plexus located between the capsule and fibrous sheath. The prostatic venous plexus is continuous superiorly with the vesical venous plexus and posteriorly with the inner vertebral venous plexus

Question 35

Where do the primary lymphatic vessels of the prostate drain into?

Answer 35

The regional lymph nodes of the pelvis

Question 36

What do the regional lymph nodes of the pelvis include?

Answer 36

Internal iliac (hypogastric) nodes Pre-vesical nodes Obturator fossa nodes Pre-sacral nodes External iliac nodes

Question 37

If metastases go beyond regional lymph nodes what lymph nodes are involved?

Answer 37

Distant lymph nodes outside the pelvis such as the superficial and deep inguinal nodes, aortic nodes and common iliac nodes

Question 38

What is the smooth muscle of the prostate is innervated by?

Answer 38

Sympathetic and parasympathetic nerve fibres

Question 39

How is the prostate innervated by sympathetic nerve fibres (T12, L1)?

Answer 39

Via the hypogastric and pelvic plexuses. This triggers smooth muscle contraction during ejaculation.

Question 40

What do the sympatheic nerves also cause in addition to contraction during ejaculation?

Answer 40

Also cause the internal urethral sphincter to contract, preventing backflow of fluid into the bladder, and innervate the vas deferens to contract and propel sperm to the urethra.

Question 41

What do the parasympathetic nerves innervate?

Answer 41

The penis