Anatomy of the prostate and perineal region

Question 1

What is the prostate

Answer 1

• Largest accessory gland of male reproductive system
• Pyramidal or doughnut shaped
• Size of a golf ball or walnut

Question 2

Borders of prostate

Answer 2

• Located inferior to urinary bladder and surrounds urethra
• Has posterolateral glandular (2/3) and anterior fibromuscular (1/3) parts
• Base is related to neck of badder
• Inferiorly, apex in contact with fascia on superior aspect of external urethral sphincter at neck of bladder and deep perineal muscle
• Anterior surface separated from pubic symphysis by retroperitoneal fat in retropubic space (cave of Retzius)
• Anterior to urethra is fibromuscular isthmus
• Posterior surface related to ampulla of rectum

Question 3

Prostate blood supply

Answer 3

Prostatic arteries from internal iliac artery )inferior vesical artery and internal pudendal and middle rectal arteries)

Question 4

Veins - prostate

Answer 4

• Veins form prostatic plexus lying between fibrous capsule and false prostatic sheath around side and base
• Veins receive dorsal vein of penis and drain to internal iliac veins
• Veins continue superiorly with vesical venous plexus and communicate with internal vertebral venous plexus that lie in front of vertebral bodies within neural canal

Question 5

What are the two capsules surrounding prostate?

Answer 5

• True fibrous capsule (dense and neurovascular, containing plexus of veins and nerves)
• False surrounding fibrous capsular prostatic sheath with condensed visceral layer of pelvic or extra-peritoneal fascia

Question 6

Lobes of prostate

Answer 6

• True fibrous capsule (dense and neurovascular, containing plexus of veins and nerves)
• False surrounding fibrous capsular prostatic sheath with condensed visceral layer of pelvic or extra-peritoneal fascia

Question 7

Zones of prostate

Answer 7

Peripheral, central and transition

Question 8

Development of prostate

Answer 8

• 30-40 glandular outgrowths from urethral epithelium into surrounding wall of urethra
• They enlarge wall of urethra
• Individual glands retain own ducts which empty into prostatic sinuses on posterior aspect

Question 9

Clinical complications of prostate

Answer 9

• Hypertrophy: benign hypertrophy of prostate is common after middle age, as part of ageing, lateral lobes affected, median lobe hypertrophy obstructs prostatic urethra and impedes urination (increase risk of cystitis and CKD)
• Digital rectal exam - prostatic enlargement palpation with full bladder via rectum
• Prostatectomy: all or just the hypertrophied part of the prostate is removed via transurethral resection
• TURP preserves nerves and blood vessels associated with the capsule that pass to the penis - increases pt’s chance of normal sexual function and urinary control after surgery

Question 10

Muscles in pelvis

Answer 10

coccygeus, levator ani (pubococcygeus and iliococcygeus) and fascia

Question 11

Course of coccyges

Answer 11

from inferior sacrum and coccyx to sacrospinus ligament

Question 12

Course of levator ani

Answer 12

anteriorly attaches to pubic bone and posteriorly attaches to ischial spines and obturator internus

Question 13

Which three things perforate pelvic floor?

Answer 13

Urethra, vagina and rectum

Question 14

Where is perineum

Answer 14

• Between upper part of medial surface of thigh and buttocks and extends from coccyx to pubis
• Includes anus and external genitalia

Question 15

Roof of perineum

Answer 15

Pelvic diaphragm

Question 16

Two triangles in perineum

Answer 16

Urogenital triangle is anterior and anal triangle posterior

Question 17

What are the two layers of perineal fasciae?

Answer 17

Superficial fatty layer

Deep membranous layer

Question 18

Superficial fatty layer of perineal fascia

Answer 18

in females, made of labia majora and mons pubis and continues superiorly with anterior abdominal wall, in males replaced with dartos muscle in penis and scrotum, continuing with Camper’s fascia on anterior abdominal wall

Question 19

Deep membranous layer of perineal fascia

Answer 19

extends and attaches to fascia lata of thigh. In males, it continues with dartos fascia of penis and scrotum, becoming continuous with Scarpa’s fascia on the lower anterior abdominal wall . In females, it becomes continuous with Scarpa’s fascia

Question 20

Gallaudet fascia

Answer 20

invests ischiocavernosus, bubospongiosus and superficial transverse perineal muscles, laterally attached to ischiopubic rami, fuses with suspensory ligament of penis/clitoris

Question 21

Urogenital hiatus

Answer 21

Thin sheet of tough fascia in urogenital triangle

Question 22

Superficial perineal pouch

Answer 22

• Superficial perineal pouch: space between perineal fascia and perineal membrane, bounded by ischiopubic rami
• In males, superficial pouch contains penis, spongy urethra, perineal muscles, pudendal nerves
• In females, superficial pouch contains clitoris, vestibule, vestibular glands, perineal muscles, pudendal nerves

Question 23

Deep perineal pouch

Answer 23

• Deep perineal pouch is between perineal membrane, pelvic diaphragm fascia and obturator fascia
• Deep perineal pouch contains urethra, urethra sphincter muscle and ischio-anal fat pads in both sexes
• Deep perineal pouch contains intermediate urethra, perineal muscles, bulbo-urethral glands and dorsal structures of the penis in males
• Deep perineal pouch contains proximal urethra and clitoris neurovasculature in females

Question 24

Clinical complications of perineal fasciae and pouches

Answer 24

• Rupture of membranous urethra can be due to pelvic girdle trauma - results in urine escaping into deep pouch
• Rupture of spongy urethra due to perineal trauma - urine escapes into superficial pouch
• Urine can’t pass into thighs or anus because of fascia

Question 25

Ischio and peri-anal abscesses

Answer 25

• Fullness and tenderness between anus and ischial tuberosity
• Infection can reach fossae after cryptitis, from a pelvirectal abscess, after a tear in anal mucous membrane, from penetrating anal wound, from anal fissure

Question 26

Boundaries of ischio-anal fossa

Answer 26

• Lateral boundary is ischium
• Medial boundary is anal sphincter
• Superior boundary is levator ani
• Posterior boundary is sacrotuberous ligament
• Anterior boundary is pubic bones

Question 27

Contents of ischio-anal fossa

Answer 27

• Contains fat to support anal canal

- Contains S2/3/4, pudendal vessels and nerve to obturator internus