Anatomy of the prostate and perineal region Flashcards
What is the prostate
- Largest accessory gland of male reproductive system
- Pyramidal or doughnut shaped
- Size of a golf ball or walnut
Borders of prostate
- 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
Prostate blood supply
Prostatic arteries from internal iliac artery )inferior vesical artery and internal pudendal and middle rectal arteries)
Veins - prostate
- 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
What are the two capsules surrounding prostate?
- 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
Lobes of prostate
- 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
Zones of prostate
Peripheral, central and transition
Development of prostate
- 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
Clinical complications of prostate
- 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
Muscles in pelvis
coccygeus, levator ani (pubococcygeus and iliococcygeus) and fascia
Course of coccyges
from inferior sacrum and coccyx to sacrospinus ligament
Course of levator ani
anteriorly attaches to pubic bone and posteriorly attaches to ischial spines and obturator internus
Which three things perforate pelvic floor?
Urethra, vagina and rectum
Where is perineum
- Between upper part of medial surface of thigh and buttocks and extends from coccyx to pubis
- Includes anus and external genitalia
Roof of perineum
Pelvic diaphragm
Two triangles in perineum
Urogenital triangle is anterior and anal triangle posterior
What are the two layers of perineal fasciae?
Superficial fatty layer
Deep membranous layer
Superficial fatty layer of perineal fascia
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
Deep membranous layer of perineal fascia
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
Gallaudet fascia
invests ischiocavernosus, bubospongiosus and superficial transverse perineal muscles, laterally attached to ischiopubic rami, fuses with suspensory ligament of penis/clitoris
Urogenital hiatus
Thin sheet of tough fascia in urogenital triangle
Superficial perineal pouch
- 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
Deep perineal pouch
- 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
Clinical complications of perineal fasciae and pouches
- 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
Ischio and peri-anal abscesses
- 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
Boundaries of ischio-anal fossa
- Lateral boundary is ischium
- Medial boundary is anal sphincter
- Superior boundary is levator ani
- Posterior boundary is sacrotuberous ligament
- Anterior boundary is pubic bones
Contents of ischio-anal fossa
- Contains fat to support anal canal
- Contains S2/3/4, pudendal vessels and nerve to obturator internus
