Male Pelvis and Perineum Flashcards
Describe the distinctive characteristics of the female pelvis
Pelvic inlet- oval/round
Sub pubic angle- wide >80 degrees
Ischial spines DO NOT project medially
Greater false pelvis- shallow
Lesser true pelvis- wide, shallow and cylindrical
distance between symphysis pubis and anterior margin of acetabulum equal to or greater than the diameter of the acetabulum
Describe the distinctive characteristics of the male pelvis
Pelvic inlet- narrow/heart-shaped Sub pubic angle- narrow (50-60 degrees) Ischial spines- project medially Greater pelvis- deep Lesser pelvis- narrow, deep and tapering distance between symphysis pubis and anterior margin of acetabulum less than the diameter of the acetabulum
Summarise the Peritoneum & Pelvic Fascia
Parietal peritoneum continues into pelvic cavity but does not reach the pelvic floor.
Pelvic viscera (except uterine tubes) are not completely covered by peritoneum.
Several folds and pouches are formed
Space between pelvic wall and peritoneum not occupied by viscera contains pelvic fascia
Pelvic fascial condensations form “ligaments” supporting viscera like cervix, vagina, prostate
List the contents of the male pelvic cavity
Ureter, bladder, urethra
Prostate, ductus deferens, seminal vesicles, bulbourethral glands
Rectum
Some of the abdominal GI tract spills into the greater pelvis- Caecum, appendix, parts of sigmoid colon and ileum
Vessel, nerves and lymphatics
Describe the peritoneum
Continuous at the pelvic inlet with the peritoneum of the abdomen- the peritoneum drapes over the viscera in the midline, forming:
pouches between adjacent viscera
folds and ligaments between viscera and pelvic walls
Anteriorly, median and medial umbilical folds of peritoneum cover the embryological remnants of the urachus and umbilical arteries respectively
These folds ascend out of the pelvis and onto the anterior abdominal wall
Posteriorly, peritoneum drapes over the lateral aspects of the upper third of the recutm, the anterior surface of the middle third: the lower third is not covered
Describe the peritoneum in males
The visceral peritoneum drapes over the top of the bladder onto the superior poles of the seminal vesicles and then reflects onto the anterior and lateral surfaces of the rectum- a rectovesical pouch occurs between the the bladder and the rectum
Posteriorly and superiorly it becomes the sigmoid mesocolon
The testicular vessels and lymphatics lie in a retroperitoneal position and course to and from the deep inguinal ring. At the ring, you can see the retroperitoneal pathway of the vas deferens as it courses toward the seminal vesicle
Describe the consequences of the retroperitoneal course of the ureters
They course beneath the testicular vessels but over the iliac vessels- they then pass deep to the vas deferens as they approach the bladder
Surgeons operating in the abdominopelvic cavity must be careful as the extraperitoneal ureters can easily be damaged, leading to the extravasation of urine into adjacent retroperitoneal and intraperitoneal spaces
What is the length of the ureter and urethra in males
Ureter- 25cm
Urethra - 20cm
What structures in the male pelvis can be felt on a digital rectal examination (DRE) of a healthy man?
Can palpate the prostate gland, and perhaps seminal vesicles if they are calcified
Anorectal ring is posterior
Normal prostate is smooth with a palpable sulcus between lateral lobes- loss of groove is indicative of cancer
Benign prostatic hypertrophy- common over 50 and may lead to obstruction of urinary outflow and distension of the bladder
Cancer of prostate- begins in posterior portion of organ and so can be palpated
Which of the two (1 or 2) bends of the male urethra can be straightened before passing a catheter?
2- during erection
What does the ductus deferens join
The seminal vesicles (found behind the prostate)
Summarise the male pelvic organs
Prostate gland surrounds 1st (prostatic) part of urethra
Ductus deferens from testis passes through inguinal canal, then over, and behind ureter to enter the urethra through the prostate
Seminal vesicles on back of bladder - open into ductus deferens between ampulla and ejaculatory duct
Outline the different regions of the male urethra
preprostatic- 1cm long- extends from base of bladder to the prostate- associated with a circular cuff of smooth muscle fibres (internal urethral sphincter)
prostatic- 3-4cm long- surrounded by the prostate- the lumen of the urethra is marked by a longitudinal midline fold of mucosa- the urethral crest
membranous part- narrow and passes through the deep perineal pouch- during its transit- the urethra is covered by the skeletal muscle of the external urethral sphincter
spongy part- surrounded by the erectile tissue of the penis (corpus spongiosum)- enlarged to form a bulb at the base of the penis and again at the end to form the navicular fossa. The two bulbo-urethral glands in the deep perineal pouch are part of the male reproductive system and open into the bulb of the spongy urethra- the external urethral orifice is the saggital slit at the end of the penis
Describe the location of the prostate
Unpaired accessory structure of the male reproductive system that surrounds the urethra in the pelvic cavity- it lies immediately inferior to the bladder, posterior to the pubic symphysis, and anterior to the rectum
Describe the prostate gland
Shaped like an inverted, rounded cone with a larger base- which is continuous above with the neck of the bladder and a narrower apex which rests below on the apex floor- the inferolateral surfaces of the prostate are in contact with the levator ani muscles
The ejaculatory ducts pass almost vertically in an anteroinferior direction through the posterior aspect of the prostate to open into the prostatic urethra.
What constitutes the secretions of the ductus deferens
The secretions of the ductus deferens, seminal vesicles (60% ) & prostate (40%) empty into the prostatic urethra to form the semen
Describe the seminal vesicles
Accessory gland of the male reproductive system- that develops as a blind-ended tubular outgrowth from the ductus deferens
The tube is coiled with numerous pocket-like outgrowths and is encapsulated by connective tissue to form an elongate structure situated between the bladder and rectum
The gland lies lateral to the ductus deferens in contact with the posterior wall of the bladder base- with its upper end just below the point of entrance of the ureter into the bladder- the very short duct leaves the lower end to join the ductus deferens at the edge of the prostate and form the ejaculatory duct
What do the seminal vesicles secrete
Produces much of the seminal fluid (rich in fructose)
Describe the bulbo-urethral glands
Small, pea-shaped mucous glands situated within the deep perineal pouch and lateral to the membranous part of the urethra- the duct from each gland passes inferomedially through the perineal membrane, to open into the bulb of the spongy urethra at the root of the penis
Together with the small glands positioned along the length of the spongy urethra- the bulbo-urethral glands contribute to lubrication of the urethra and pre-ejaculatory emission from the penis
Describe the Prostatic Urethrawhere urinary & reproductive tracts meet
Midway along the length of the urethral crest it is enlarged to form a somewhat circular elevation (the seminal colliculus)- which can be used to determine the position of the prostate gland during transurethral transection of the prostate
a small- blind ended pouch- the prostatic utricle- opens onto the centre of the seminal colliculus
on each side of this are the openings of the ejaculatory ducts