Lecture 5 - Male Pelvis and Perineum Flashcards
What are the differences between female and male pelves?
What is the orientation of the pelvic girdle of the male and female?
ASIS and pubic tubercles are in the same plane, with greater and lesser pelves being continuous
Where does the pelvic peritoneum extend to?
Continues into pelvic cavity but doesn’t reach the pelvic floor, not completely covering pelvic viscera (apart from uterine tubes)
What is the structure of the pelvic peritoneum?
Several folds and pouches are formed
What is present in the space between the pelvic wall and peritoneum not occupied by viscera?
Pelvic fascia which when condensed form ligaments supporting viscera like the cervix, vagina and prostate
What are the contents of the male pelvic cavity?
Ureter, bladder, urethra, prostate, ductus deferens, seminal vesicles, bulbourethral glands, rectum, vessels, nerves, lymphatics; in greater pelvis: caecum, appendix, parts of sigmoid colon and ileum
What is the organisation of the male pelvic organs?
What structures in the male pelvis can be felt on a digital rectal examination (DRE) of a healthy man?
Prostate
Which of the two (1 or 2) bends of the male urethra can be straightened before passing a catheter?
2
Where is the prostate gland and ductus deferens located?
PG surrounds 1st part of urethra, ductus deferens from testis passes through inguinal canal then over and behind ureter to enter urethra through the prostate
Where are the seminal vesicles located?
On back of bladder which open into ductus deferens between ampulla and ejaculatory duct
What does the male bladder and prostate look like?
Where does the male bladder ‘sit’?
On the prostate which is transfixed by the 1st part of urethra
From what ducts does the semen form from?
Ductus deferens, seminal vesicles and prostate empty into prostatic urethra to form the semen
How does the prostate drain into the urethra?
What is the internal urethral sphincter?
Smooth muscle well organised in males -> closes during ejaculation by sympathetic stimulus
When navigating a catheter where can complications occur?
Tip of catheter may become lodged in prostatic utricle
Where does the male pelvis receive arterial supply from?
Where does the testis receive arterial supply from?
From testicular artery arising from abdominal aorta
What is the shape of the perineum?
Diamond shape area between pubic symphisis, ischial tuberosities and coccyx, divided into urogenital and anal triangles
What is present in the anal triangle?
Ischio-anal fossae (fat-filled spaces separating anal canal and levator ani from pelvis walls)
What is present in the urogenital triangle?
Divided into superficial and deep parts by the perineal membrane
What is the perineal membrane?
Thick triangular fascial structure attached to pubic arch with free margin posteriorly and a small gap anteriorly
What is the deep perineal space?
Above the perineal membrane and below the fascia of pelvic diaphragm
What is the superficial perineal space?
Below the perineal membrane and perineal fascia
When does the deep and superficial space become real spaces?
When fluid leaks into them -> normally are potential spaces
What are the superficial perineal structures of males?
What does the perineal membrane fill?
The urogenital triangle and the erectile tissues and associated skeletal muscles are anchored to this
What are the contents of the superficial perineal pouch?
Median erectile tissue (corpus spongiosum) - bulb of penis [F= divides round vestibule to form vestibular bulbs], lateral erectile tissue - masses attached to ischiopubic rami. Both meet to form shaft and head of penis or clitoris
What is the erectile tissue in perineum surrounded by?
Skeletal muscles
How is the rectum perfused by vessels?
One pair of arteries from IMA and 2 pairs from internal iliac artery and venous drainage is similar, so there is an important portal systemic venous anastomosis around the lower recutm and anal canal
What are the ischioanal fossae?
Fat-filled spaces in the anal triangle which allow recto-anal and vaginal expansion -> in lateral wall, the pudendal neuro-vascula bundle supplying the perineum (inc. lower rectum) is present
What is the structure of the male reproductive tract?
What is the structure of the testis and its associated structures?
What is the structure of the penis?
Where do the crura of the corpus cavernosae attach?
To the ischiopubic rami, with the urethra traversing the length of the corpus spongiosum
Where can catheters get caught in the erectile tissue in males?
Navicular fossa (fossa terminalis)
What is the structure of the erectile tissue in the male?
Where does the penis get its blood supply from?
Main: Internal pudendal artery from internal iliac. Deep artery supplies corpora cavernosa. Dorsal artery supplies skin and connective tissue. Artery of bulb supplies the bulb, corpus spongiosum, glans and urethra
What are the arteries that supply the cavernous spaces in the penis?
Helicine arteries - parasympathetic stimulation causes relaxation allowing blood flow
What are the nerves of the pelvis?
Contents supplied ONLY by autonomic nerves, sympathetic from T10-L2 segments via hypogastric plexus. Parasympathetic from S2-4 outflow. Perineum supplied by somatic pudendal nerve (S2-4)
What is the sensation of the pelvis like?
Visceral and poorly localised -> pain referred to suprapubic region and perineum
What are the nerves of the pelvis and perineum?
What does the pudendal nerve innervate?
SOMATIC (S2-4) -> sensory: dorsal nerve of penis - sensory to penile skin, glans AND motor: perineal muscles, bulbospongius and ischicavernosus causing ejaculation and external urethral sphincter
What do the parasympathetic S2-4 nerves cause?
Vasodilation of arterioles in erectile tissue and secretion in prostate, bulbourethral glands
What do sympathetic L1-2 nerves cause?
Contraction of smooth muscles of epididymis, vas deferens, seminal vesicles, prostate causing emission AND contraction of internal urethral sphincter in males to prevent reflux of semen
What are the nerves of the perineum?
Somatic mainly from sacral segments -> Pudendal (S2-4), supplies all perineal skeletal muscles and sensory to penis, lower urethra, lower rectum and anal canal
Where do somatic nerves leave the pelvis from?
Lumbosacral plexus
What is the pudendal nerve?
Somatic nerve, passes briefly from pelvis to buttock, passing behind fibrous posterior edge of Levator ani (forward below) and is the first in the lateral wall of the ischioanal fossa then branching to anterior perineum, penis/clitoris and scrotum/vulva
Where is the pudendal nerve located?
How does an erection occur?
Central parasympathetic pathway activated by psychic stimulation, with pudendal artery relaxing allowing blood flow into cavernous spaces of erectile tissue
How does secretion occur in genitalia?
Stimulation of parasympathetic ganglia on prostate, seminal vesicles and other glands (F)
How does emission occur in genitalia?
Central sympathetic pathway is activated and SM contraction of vas deferens, prostate and seminal vesicles -> internal urethral sphincter (M) contracts. Bladder muscle contraction is prevented by sympathetic inhibitory action
How does ejaculation occur?
Entry of semen into urethra triggers somatic reflex (via pudendal nerve) causing contraction of bulbospongiosus muscle
How does detumescence occur?
Selected sympathetic nerves supplying pudendal arterioles are activated causing arteriolar constriction to restrict blood supply to cavernous spaces
