ANA 206 Development of the GIT

Question 1

The foregut is supplied by

Answer 1

The celiac artery (branch of the aorta)

Question 2

The midgut is supplied by

Answer 2

The superior mesenteric artery (branch of the aorta)

Question 3

The hindgut is supplied by

Answer 3

Inferior mesenteric artery (branch of the aorta)

Question 4

Discuss midgut rotation

Answer 4

1. Before returning into the abdominal cavity, the prearterial segment of the midgut loop undergoes 90° anti-clockwise rotation. As a result, the prearterial segment comes to the right and the postarterial segment goes to the left. The prearterial segment of the midgut loop elongates extensively and forms coils (becomes convoluted) of jejunum and ileum, which lie on the right side of the superior mesenteric artery, outside the abdominal cavity.
2. As these coils of jejunum and ileum return to the abdominal cavity, the midgut loop undergoes a second 90° anticlockwise rotation so that coils of jejunum and ileum (from the prearterial segment) pass behind the superior mesenteric artery. As a result, the duodenum goes behind the superior mesenteric artery.
3. Lastly when the postarterial segment returns to the abdominal cavity it undergoes a third 90° anticlockwise rotation. As a result, cecum and an
   appendix that develops from the cecal bud (on the post arterial limb) now comes to lie on the right side just below the liver