VH Dissector: Midgut and Hindgut

In this section, we will begin by focusing on the blood supply and viscera associated with the midgut. These organs are all supplied by the superior mesenteric artery.

As you work through each step, please rotate, dissect and highlight this area to get the full effect of the aorta and arteries and their relationship to the superior mesenteric artery.

Start with the superior mesenteric artery and iliac arteries.

STEP 1

Notice that the superior mesenteric artery crosses over the duodenum.

Add the inferior pancreaticoduoenal artery.

Note the relationship of this artery and the superior mesenteric artery to the head of the pancreas. This part of the pancreas is known as the uncinate process.

STEP 2

Remember that the midgut rotates around the superior mesenteric artery and the organs supplied by this artery are intraperitoneal.

Add the jejunal arteries.

STEP 3

Add the duodenojejunal flexure which is the point where the duodenum connects with the intraperitoneal jejunum.

STEP 4

Add in the jejunum.

STEP 5

Add the ileal arteries.

STEP 6

Now, add the ileum.

STEP 7

Now, add the ileocolic artery

STEP 8

Add the cecum.

STEP 9

Add the right colic artery.

STEP 10

Add the middle colic artery.

STEP 11

Add the ascending colon.

Note that the ileocolic and the right colic perfuse the cecum, and ascending colon.

Also note the origin of the middle colic artery on the superior mesenteric artery.

STEP 12

Add the transverse colon. Note that it is at the transverse colon that we have blood supply by both a midgut branch (middle colic artery) and hindgut branch (branch of inferior mesenteric). This is an important area of collateral circulation.

STEP 13

Why does the transverse colon appear to dip down relative to the ascending and descending colon?

The ascending and descending colon are both attached to the lateral gutters of the posterior abdominal wall. The transverse colon is not attached. Review the embryology of the rotation and elongation of the colon to see how this occurs.

Now we will continue to the inferior mesenteric artery which supplies hindgut structures:

To look at the inferior mesenteric artery, we must first remove the jejunum and the ileum. Can you find the inferior mesenteric artery.

STEP 14

Here we have removed the highlights from other vessels and just highlighted the inferior mesenteric artery for you.

STEP 15

Add the sigmoid arteries.

STEP 16

Add the left colic arteries.

STEP 17

Add the superior rectal artery.

STEP 18

Add the rectum.

STEP 19

Add the sigmoid colon.

STEP 20

Add the descending colon.

STEP 21

This completes the arterial supply to the major organs of the abdomen. Continue to the next section for the dissection of the portal system

Credits:

VH Dissector steps modified for Drexel Dissector by Dr. Haviva Goldman from original website activity created by Jeffrey Fahl, MD, Kyle Petersen, PhD, Richard Drake, PhD, Alesha Petitt, MA, Claira Ralston, MS and Kim Price, MA and modified by Jeffrey Fahl, MD, Michael Smith, PhD, Albany Medical College.