TMA IM Flashcards
hindgut organs
the distal 1/3 of the transverse colon, splenic flexure, descending colon, sigmoid colon and rectum.
path of the IM
arises at L3, near the inferior border of the duodenum, 3-4 cm above where the aorta bifurcates into the common iliac arteries. As the artery arises from the aorta, it descends anteriorly to its parent vessel, before moving to the left side. It is a retroperitoneal structure – situated behind the peritoneum.
what are the three major arteries of the IM
left colic artery, sigmoid artery and superior rectal artery.
what are the two majour anatomoses of the IM and what do both involve
both involving a union with branches of the superior mesenteric artery:Marginal artery (of Drummond) and Arc of Riolan
why is the splenic flexure described as a watershead area? and what are the clinical impications
when an area has dual blood supply from the most distal branches of two large arteries. Whilst this has the advantage of being more resistant to ischaemia if one of the arteries becomes occluded, it makes the area more sensitive to systemic hypoperfusion.
desribe the Marginal artery of Drummond
forms a continuous arterial circle along the inner border of the colon. Straight vessels (vasa recta) arise from the artery to supply the colon. It is formed by the union of several branches; the ileocolic, right colic and middle colic of the SMA and left colic and sigmoid branches of the IMA.
desribe the arc of riolan
anastomosis between the middle colic branch of SMA and the left colic branch of IMA. It is less common than the marginal artery, and indeed its existence has been questioned by some surgeons.
what deos the left colic supply
distal 1/3 of the transverse colon and the descending colon
path of the left colic
it travels anteriorly to the psoas major muscle, left ureter and left internal spermatic vessels, before dividing into ascending and descending branches
path of the asceinding branch of the left colic
crosses the left kidney anteriorly, before entering the mesentery of the transverse colon, moving superiorly. It supplies the distal 1/3 of the transverse colon, and the upper aspect of the descending colon.
path of the desceinding branch of the left colic
moves inferiorly to supply the lower part of the descending colon. It anastomoses with the superior sigmoid artery.
what do the sigmoid arteries supply
descending colon and the sigmoid colon
path of the sigmid arteries includeing birufication pathways
There are typically 2-4 branches, with the uppermost branch termed the superior sigmoid artery. They run inferiorly, obliquely and to the left, crossing over the psoas major, left ureter and left internal spermatic vessels.
path of the superior rectal artery
The superior rectal artery is a continuation of the inferior mesenteric artery, supplying the rectum. It descends into the pelvis, crossing the left common iliac artery and vein.
At the S3 vertebral level, the artery divides into two terminal branches – one supplying each side of the rectum.
what happens within the walls of each retum?
smaller divisions of these branches eventually communicate with the middle and inferior rectal arteries.
