Midgut

Question 1

Jejunum and ileum neurovasculature and lymphatics

Answer 1

• the juxta-intestinal nodes (found along peripheral arterial arcades)
• the intermediate mesenteric nodes (along the jejunal and ileal arteries), and
• (central) superior mesenteric nodes (along the length of the superior mesenteric artery).

Arterial supply: arterial arcades of superior mesenteric artery

Venous drainage: venous arcades -> superior mesenteric vein -> portal vein

Innervation: Lesser splanchnic nerves (T9-T10) via celiac and superior mesenteric plexus (sympathetic), vagus nerve (CN X) augments peristaltic activity of enteric nervous system (parasympathetic)

Question 2

Large intestine neurovasculature and lymphatics

Answer 2

Arterial supply- The midgut (from the ileocecal junction, the cecum and vermiform appendix to the proximal two-thirds of the transverse colon) region receives arterial supply from the superior mesenteric artery and the hind gut (from the distal ⅓ of the transverse colon to the sigmoid colon) is supplied by the inferior mesenteric artery.

Innervation-
Parasympathetic- The vagus nerve (CNX) enters the abdominal cavity via the oesophageal hiatus of the diaphragm. The pelvic splanchnic nerves (S2-4).
Sympathetic- The T10-L2 thoracolumbar outflow of sympathetic fibres are responsible for the inhibitory activity along the large intestines. They form synapses at the superior and inferior mesenteric, and the inferior hypogastric plexuses.
Superior mesenteric plexus- cecum, appendix, ascending and transverse colon
Inferior mesenteric plexus- colon from the left colic flexure to the rectum.
Inferior hypogastric plexus- rectum.

Lymph drainage-
- epicolic nodes rest on the outer surface of the intestinal wall.
- paracolic nodes lie along the intestinal margin.
- intermediate nodes that lie along the arterial branches of the superior and inferior mesenteric arteries.
- preaortic nodes that are found at the branching point of the coeliac trunk and the superior and inferior mesenteric arteries.