GA Lab 2 - Male Perineum & Pelvis Flashcards
What is the perineal membrane?
Thick fibrous sheath that fills the urogenital triangle
Attachments of the perineal membrane?
Free posterior border and attached laterally to the pubic arch
Role of perineal membrane?
Provides support for the external genitalia, which are attached to its inferior surface
What does the perineal membrane separate?
Separates the deep and superficial pouches
What is the root of the penis made up of?
Both corporus spongiosum and corpora cavernosa
When does the body of the penis start?
Begins when the two proximal free parts of the corpora cavernosa and corpus spogiosum meet = free part of the penis
What does Colle’s fascia attach to? What is it continuous with?
Attached:
- To posterior end of the perineal membrane (does not extend to anal triangle)
- To ischiopubic rami (does not extend into the thigh)
Continuous with fascia on the anterior abdominal wall
What is Darto’s fascia?
Superficial fascia of scrotum made of BOTH Scarpa’s and Camper’s fascia
6 layers around testes and what they correspond to in the anterior abdominal wall?
- Skin
- Dartos fascia => BOTH Scarpa’s and Camper’s fascia
- External spermatic fascia => external oblique aponeurosis
- Cremasteric fascia and muscle => internal oblique muscle
- Internal spermatic fascia => transversalis fascia
- Obliterated processus vaginalis = visceral and parietal tunica vaginalis => parietal peritoneum
9 contents of spermatic cord?
- Genital branch of genitofemoral nerve
- Deferential artery + vein
- Ductus deferens
- Pampiniform plexus of testicular veins
- Testicular artery from abdominal aorta
- Cremasteric artery and vein
- Sympathetic efferents and visceral afferents (later ones carrying pain)
- Lymphatics
- Remnants of the processus vaginalis
What is the spermatic cord enveloped by?
External spermatic fascia
What is the scrotal ligament? Embryological derivation? Purpose? Other name?
Ligament that secures the testis to the most inferior portion of the scrotum
- Remnant of gubernaculum in a fetus
- Tethering it in place and limiting the degree to which the testis can move within the scrotum
= testicular ligament
Does the visceral layer of the tunica vaginalis cover the whole testis?
NOPE - not the posterior aspect
Other name for deferential artery?
Artery of ductus
Position of ductus deferens in relation to the spermatic cord?
Posterior
Is the perineal body more prominent in males or females?
Females
What defines the superior margin of the superficial perineal pouch?
Perineal membrane
Location of perineal membrane with regards to erectile tissues and their muscles?
Superior
What is the deep fascia of the penis called? What does it contain? What does it NOT contain?
Buck’s fascia
Contains corpora cavernosa, corpus spongiosum, dorsal arteries, deep dorsal vein, dorsal nerve
Does NOT contain superficial dorsal vein
What is the terminal branch of the anterior trunk of the internal iliac artery?
Inferior gluteal artery
Levator ani muscles:
- Origin
- Insertion
- Innervation
- Function
- In a line around the pelvic wall: from the posterior aspect of the pubic bone => tendinous arch of obturator internus muscle (thickening of the obturator internus fascia) => ischial spine
- Anterior part: superior surface of the perineal membrane
- Posterior part: meets its partner on the other side at the perineal body, around the anal canal, and along the anococcygeal ligament
- Branches direct from the anterior ramus of S4, and by the inferior rectal branch of the pudendal nerve (S2 to S4)
- Contributes to the formation of the pelvic floor, which supports the pelvic viscera
- Maintains a 90 degree angle between the rectum and anal canal
- Reinforces the external anal sphincter
- In women: functions as a vaginal sphincter (sphincter vaginae) during orgasm
- In men: principal support for the prostate (levator prostatae)
Describe the pathway of the inferior rectal nerve and its function.
Penetrates through the fascia of the pudendal canal, and courses medially across the ischio-anal fossa
- Innervates the external anal sphincter and related regions of the levator ani muscles
- Provides general sensory for the skin of the anal triangle
What 3 structures run on the dorsal surface of the penis?
- 2 dorsal arteries
- 1 deep dorsal vein
- Dorsal nerve
From what artery does the dorsal artery of the penis originate from?
Internal pudendal artery
What is the bulb of the penis?
Proximal part of corpus spongiosum
What is the root of the penis made of?
Crura + bulb of the penis
What is the navicular fossa?
Enlarged distal portion of the spongy urethra at the end of the penis within the glans
What runs within the corpora cavernosa?
Deep artery of the penis
What separates the corpora cavernosa and the corporus spongiosum? What does it form?
Tunica albuginea of corpora cavernosa
Forms a septum between the 2 corpora cavernosa
Vertebral level of male rectum?
S3
Lymphatic drainage of the rectum?
- Superficial inguinal nodes following inferior rectal artery to internal pudendal artery
- Internal iliac nodes following middle rectal artery to internal iliac artery
- Inferior mesenteric nodes following superior rectal artery to the IMA
Rectum innervation?
- Top half: autonomic afferent nerves
- Bottom half: inferior hypogastric plexuses
What is the median umbilical ligament?
Remnant of the urachus, which contributes to the formation of the bladder
Connects the umbilicus to the bladder
What are the puboprostatic ligaments?
Paired fibromuscular bands anchoring the neck of the bladder and urethra to the posterior aspect of the pubic bone
What crosses over the ureters in men and women?
- Men: ductus deferens posterior to the bladder
2. Women: uterine artery lateral to the cervix
What is the superior surface of the male bladder covered by?
Peritoneum
Bladder innervation?
Inferior hypogastric plexuses
Do the bulbo-urethral glands connect to the membranous urethra?
NOPE, to the spongy
What is located anterior to the prostate?
Pubic symphysis
What artery supplies the prostate?
Inferior vesicle artery
Venous drainage of prostate?
Prostatic venous plexus draining to the internal iliac veins
Lymph drainage of prostate?
Internal iliac nodes
Innervation of prostate?
Inferior hypogastric plexuses
What forms the ejaculatory duct?
Ductus deferens joined by ducts of seminal vesicles
What do the ducts of the bulbo-urethral glands pass through to reach spongy urethra?
Perineal membrane
Vertebral level of internal iliac artery?
L5/S1
What does the iliolumbar artery supply?
Posterior abdominal wall
What does the lateral sacral artery supply?
Sacrum
Where do the para-aortic nodes drain to?
Thoracic duct
What is the sciatic nerve made of?
L4-S3
Describe the pathway of the sciatic nerve.
Exits through greater sciatic foramen inferior to piriformis => divides into 2 major branches: common fibular and tibial nerves
What does the sciatic nerve innervate?
- Muscles in the posterior compartment of the thigh and muscles in leg and foot
- Carriers sensory fibers from skin of foot and lateral leg
10 branches of sacral plexus?
- Superior gluteal nerve
- Inferior gluteal nerve
- Nerve to quadratus femoris and inferior gemellus
- Posterior femoral cutaneous nerve of the thigh
- Perforating cutaneous
- Nerve to piriformis
- Nerves to levator ani, coccygeus and external anal sphincter
- Coccygeal plexus
- Pudendal nerve
- Sciatic nerve
Superior gluteal nerve:
- Spinal segment?
- Function?
L4-S1
Gluteus medius and minimum
Tensor fasciae latae
Inferior gluteal nerve
- Spinal segment?
- Function?
L5-S2
Gluteus maximum
Nerve to quadratus femoris and inferior gemellus
- Spinal segment?
- Function?
L4-S1
Quadratus femoris and inferior gemellus
Posterior femoral cutaneous nerve of the thigh
- Spinal segment?
- Function?
S1 + S3
Skin of the posterior aspect of the thigh
Perforating cutaneous
- Spinal segment?
- Function?
S2 + S3
Skin over gluteal fold
Nerve to piriformis
- Spinal segment?
- Function?
L5-S2
Piriformis muscle
Nerves to levator ani, coccygeus and external anal sphincter
- Spinal segment?
- Function?
S4
Levator ani, coccygeus and external anal sphincter + small patch of skin between anus and coccyx
Coccygeal plexus
- Spinal segment?
- Function?
S4-Co
Perianal skin
Role of pelvic sympathetic fibers?
- Vasoconstriction
- Cause smooth muscle contractions of internal urethral and anal sphincters
- Cause smooth muscle contractions associated with reproductive tracts
- Important in moving secretions from epididymis into urethra
Role of pelvic parasympathetic fibers?
- Vasodilation
- Stimulate bladder contractions
- Stimulate erection
- Modulate activity of ENS of colon distal to left colic flexure
At what part is the spongy urethra NOT protected by erectile tissue? Consequence?
At point where it becomes the membranous urethra
Potential damage site
What is the sacrogenital fold?
Peritoneal fold that extends backward from the sides of the bladder of the male or uterus of the female on either side of the rectum to the sacrum, forming the lateral boundaries of the rectovesical pouch
What is found on each side of the rectum?
Pararectal fossa
What is found on each side of the bladder?
Paravesicular fossa
What is the supravesicular fossa?
Fossa superior to bladder between that and the pubic symphysis
What is the rectal ampulla?
Lower expanded portion of the rectum
Relationship of ureter with regards to inferior epigastric artery?
Passes lateral and then posterior as it bends to course medially
2 branches of external iliac artery?
- Inferior epigastric artery
2. Deep iliac circumflex artery
Where does the deep dorsal vein of the penis drain? What does it drain?
Prostatic plexus of veins
Drains glans penis and corpora cavernosa
What do the superficial veins of the penis drain?
Prepuce and skin of penis
Does Colle’s fascia extend to anal triangle?
NOPE
Differences between Colle’s and Darto’s fascias?
- Colle’s in perineum/Darto’s in scrotum
- Colle’s corresponds to a continuation of Scarpa’s fascia ONLY (from anterior abdominal wall)/Darto’s corresponds to both Scarpa’s and Camper’s fused together
Scarpa's = membranous superficial fascia Camper's = fatty superficial fascia
When do the testes descend into scrotum? How?
7-month-old fetus via the inguinal canal
3 phases:
- Testes attachment to the cranial suspensory ligament is severed + gubernaculum contracts (both hormone induced)
- Transabdominal descent brings testes down to inguinal ring located cranially to the scrotum
- Transinguinal descent brings testes into scrotum