Flashcards in Descending and sigmoid colon (Dave's notes) Deck (17)
What is the length of and what are the boundaries of the descending colon
30cm from splenic flexure to pelvic brim. Plastered to the posterior abdominal wall. 20% have a mesentary.
Describe the relations of the descending colon
Lies on the lumbar and then iliac fascia
Where are the teniae coli located on the descending colon?
As they do for the ascending colon; anterior, posteriomedial and posterolateral
How does the descending colon move during development?
It hinges to the left; vessels lie immediately below the peritoneum
What is the blood supply of the descending colon?
The left colic, which arises from the IMA
Describe the length and boundaries of the sigmoid colon
Up to 45cm long from pelvic brim to commencement of the rectum at S3, starts with the commencement of mesentery
How do the teniae differ in the sigmoid relative to the descending colon?
Sacculations persist but the teniae are much wider
Why is diverticulosis most common in this part of the bowel?
Appendages epiploicae are most common here
Describe the shape of the sigmoid mesentary
The mesentary is hinged but did not completely fuse so forms an A-shaped base with the limbs diverging. Fans out from a 10cm base to a 40cm border. Vessels lie in this mesentary
What landmark marks the apex of the sigmoid's mesentary?
The bifurcation of the common iliac artery over the SI joint
To what is the lateral limb of the sigmoid mesentary attached?
The external iliac artery to halfway to the inguinal ligament (5cm)
To what landmark does the medial limb of the sigmoid mesentary extend?
The medial limb of the sigmoid mesentary extends to the midline at S3
What is the blood supply of the sigmoid colon?
Sigmoid arteries from the IMA
Describe the venous drainage and lymphatic drainage of the sigmoid colon
Veins and lymph follow the arterial supply
What is the nerve supply of the sigmoid colon?
Sympathetic and parasympathetic. Pain fibres give periumbilical pain from the midgut and hypogastric from the hindgut????
Describe the parasympathetic supply to the descending colon and sigmoid colon
Parasympathetic supply to the splenic flexure is via vagi, and beyond this is from the pelvic splanchnic nerves