Pelvis and Perineum 1.3 Flashcards
What does the pudendal nerve and its branches innervate (M)?
skin and skeletal muscles of the male perineum
Where does the pudendal nerve arise from? (M)
anterior rami of S2, S3, and S4 spinal cord levels
After emerging from the pudendal (Alcock’s) canal what does the pudendal nerve divides into? (M)
- inferior anal (rectal) nerves
1. the perineal nerve
2. superficial and deep branches of the perineal nerve (which also supply the scrotum)
3. the dorsal nerve of the penis.
Where do paraysmpathetic fibers arise (M)?
S2-S4 levels
How do the parasympathetic fibers travel (M)?
in pelvic splanchnic nerves to the inferior hypogastric plexus and prostatic nerve plexus
What do parasympathetic fibers stimualte?
- release of nitric oxide from the nerve endings and endothelial cells of the erectile tissues
- which relaxes smooth muscle tone and increases blood flow to permit erection
What is erectile dysfunction?
inability to achieve or maintain penile erection sufficient for sexual intercourse
What does nitric oxide released by the pelvic splanchnic parasympathetic nerve fibers and endothelial cells normally cause?
- dilation of the arteries supplying blood to the erectile tissues
- when this mechanism is compromised, ed results
How do drugs targeting ed work?
aid smooth muscle relaxation by augmenting the action of nitric oxide
What is the primary blood supply for the pelvic viscera and perineum (W)?
internal iliac artery
How does the internal iliac artery divide (W)?
- anterior trunk (which largely supplies pelvic viscera and the perineum)
- posterior trunk
What do the branches of the posterior trunk supply (W)?
pelvic walls or pass through the greater sciatic foramen into the gluteal region
Does the branching pattern of the internal iliac artery vary? (W)
greatly, so it is advisable to name the arteries according to the structures that they supply
Where do the veins drain? (W)
- Veins draining the corresponding structures are similarly identified and named
- drain into the internal iliac vein and into the common iliac vein on each side and then into the inferior vena cava
How do cancer cells originating in the pelvic viscera metastasise? (W)
- via the venous system and will generally follow the venous drainage back toward the central venous circulation
- most of the pelvic viscera this means via the inferior vena cava, although some spread to the adjacent veins of the vertebral column is also common
What is the internal pudendal artery (W)?
branch of the anterior division of the internal iliac artery
What is the course of the internal pudendal artery (W)?
courses to the perineum by passing through the lesser sciatic foramen and the pudendal (Alcock’s) canal
What does the internal pudendal artery give off (W)?
- the inferior rectal artery
- the perineal artery
What do branches of the perineal artery supply? (W)
- bulb of the vestibule
- crus of the clitoris
- clitoris
What accompanies all the branches of the internal pudendal artery? (W)
- Venous branches
- names correspond to the names of the arterial branches
Where does the lymphatic network of the perineum drain? (W)
- largely to the superficial inguinal lymph nodes
- then along the iliac nodes to the paraaortic (lumbar) nodes in the abdomen
- Infections and cancer cells travelling in the lymphatic follow this same pathway
What are the 3 sets of veins draining blood from the rectum and anal canal?
- Inferior rectal veins from the internal pudendal vein (caval system)
- Middle rectal veins from the internal iliac vein (caval system)
- Superior rectal vein from the inferior mesenteric vein (portal system).
What do these valveless veins provide?
important portacaval anastomosis around the rectum should the venous return by the portal or caval system be impeded
Where is there a lot of anastomoses?
between the venous tributaries in the walls of the anal canal and rectum, corresponding arteries accompany these veins
What is hemorrhoids?
symptomatic varicose dilations of submucosal veins that protrude into the anal canal or extend through the anus
How common is hemorrhoids?
affect 50% to 80% of individuals (more common after pregnancy)
What are the different types of hemorrhoids?
- internal hemorrhoids (dilations of veins of internal rectal plexus)
- external hemorrhoids (dilations of veins of external rectal plexus)
- mixed (combination of both)
What does the internal iliac artery supply? (M)
pelvic structures, perineum, and external genitalia
Within the spermatic cord what does the pampiniform venous plexus surround? (M)
the testicular artery and drains blood from the testes into the testicular vein
What does the pampiniform venous plexus act as? (M)
a countercurrent cooling mechanism that cools the arterial blood flowing in the testicular artery
When does spermatogenesis occur? (M)
only if the temperature is lower than body temperature
Where do the testes reside? (M)
- in the scrotum a
- possess this countercurrent mechanism to maintain the appropriate ambient temperature
How common is prostatic carcinoma?
most common visceral cancer in men and the second leading cause of death in men over 50 years of age, after lung cancer
Why does prostatic carcinoma metastsise?
- Pelvic lymphatics
- rich prostatic venous plexus drainage facilitate the metastatic spread to distant sites
What does the prostatic artery supply (M)?
the prostate gland
What is the prostatic artery a branch of? (M)
nferior vesical artery (the artery to the urinary bladder)
Is there variability in the arteries to the pelvic viscera? (M)
significant variability in the arteries to the pelvic viscera can exist, and the arteries often form small anastomotic connection
What are extensive venous plexuses associated with? (M)
bladder, rectum, and prostate in the male
Why is there common cancer cell metastases? (M)
- prostate’s close apposition to adjacent viscera
- its rich prostatic venous plexus and lymphatic system provide pathways for direct-invasion, lymphatic, and/or blood-borne cancer cell metastases to adjacent viscera (bladder, urethra, seminal vesicle, rectum), the bony pelvic walls, the spine, and distant sites
What is the internal pudendal artery a branch of? (M)
anterior division of the internal iliac artery
How does the internal pudendal artery enter the perineum? (M)
- by passing out of the gluteal region
- through the lesser sciatic foramen
- coursing through the pudendal (Alcock’s) canal
What does the internal pudendal artery give rise to? (M)
- inferior rectal artery
2. perineal artery
What do branches of the perineal artery supply? (M)
- bulb of the penis
- corpus cavernosum
- the penis
- the scrotum
What accompanies the branches of the internal pudendal artery? (M)
- Venous tributaries
- names of these veins correspond to the names of the arterial branches
What can extravasation of urine from a rupture of the spongy urethra spread into? (M)
- the superficial pouch of the urogenital triangle
- into the scrotum beneath the dartos fascia
- around the penis between the dartos and deep penile (Buck’s) fascia
- and into the lower abdominal wall beneath the membranous (Scarpa’s) fascia
In women how does the peritoneoum pass from the anterior abdominal wall? (W)
over the superior surface of the urinary bladder
What does the peritoneum then form and pass over? (W)
passes from the bladder to the uterus, forming the vesicouterine pouch between these 2 structures
What does the peritoneum continue over?
- over the fundus
- body of the uterus
- posterior fornix
- wall of the vagina
How does the peritoneum reflect?
onto the anterior and lateral sides of the rectum
What is between the rectum and uterus?
rectouterine pouch
Posteriorly and superiorly what does the peritoneum become?
the sigmoid mesocolon
What is in the suspensory ligament of the ovary?
ovarian vessels, nerves, and lymphatics
How does the round ligament of the uterus travel?
passes anteriorly and laterally to the deep, or internal, inguinal ring
What does the broad ligament of the uterus provide?
- Support to uterus
2. With pelvic diaphragm and cardinal and uterosacral ligament helps keeps uterus from prolapsing
