Pelvic Anatomy 5 Flashcards
Relate pelvic development from splanchnopleure and somatopleure (gut vs. body wall) to the organization of muscles, nerves, blood supply, and lymphatic drainage. Define hemorrhoids and describe how they relate to venous drainage and portal hypertension.
1
Q
What does the rectum and superior part of the anal canal develop from? What about the inferior part?
A
- Superior part develops from the hindgut
- Inferior part derives from the body wall
2
Q
What happens at the pectinate line?
A
- Found in the adult anal canal
- Site of the cloacal membrane where endoderm and ectoderm join
- At the level of the anal valves at the inferior end of the anal columns
- White line is the change in epithelium to skin below this
- Anal glands open under the anal valve
3
Q
What are the muscles of the rectum? What is the innervation?
A
- Smooth muscle of gut wall terminates as internal anal sphincter
-
External anal sphincter is skeletal muscle
- supplied by pudendal nerve
4
Q
What are the major vessels that supply the rectum?
A
-
Superior rectal (hemorrhoidal) arteries and veins
- continuations of the inferior mesenteric vessels
- branches of the internal iliac
- continuations of the inferior mesenteric vessels
5
Q
What are hemorrhoids? What type of hemorrhoids does portal hypertension lead to?
A
- Dilated rectal veins can cause hemmorhoids
- Internal vs external
- relate to the two systems of venous drainage above and below the pectinate line
- internal hemorrhoids can be caused by portal hypertension
- Visceral sensory innervation of internal hemorrhoids is asymptomatic
- General sensory innervation of external hemorrhoids is intense
6
Q
Describe the nerves that supply the rectum.
A
-
Above pectinate line:
- autonomic nerves and visceral sensory nerves supply hindgut derivatives (mucosa and smooth muscle of rectum and upper anal canal)
-
Below pectinate line:
- Somatic innervation via pudendal nerve
- ventral rami of nerves S2, 3, and 4 supplies lower anal canal and external anal sphincter
- Somatic innervation via pudendal nerve
7
Q
Describe the lymphatics of the rectum.
A
- Body wall lymph drains to superficial inguinal nodes, then go deep
- Hindgut lymph follows route of iliac vessels or inferior mesenteric vessels
