Transverse colon extends across the abdomen, occupying the umbilical region. It is about 15 inches long, beginning at the right colic flexure below the right lobe of liver. Afterwards, it hangs downward, suspended by the transverse mesocolon from pancreas. In its last part, it ascends to the left colic flexure below the spleen. The left colic flexure lies at a level higher than the right and is suspended from the diaphragm by the phrenicocolic ligament.
The transverse colon has its own mesentery, known as the transverse mesocolon. It suspends the transverse colon from the anterior border of pancreas. It must be appreciated that the transverse mesocolon is attached to the superior border of transverse colon while the greater omentum is attached to its inferior border. Because of the variable length of the transverse mesocolon, the position of the transverse colon in the abdomen is extremely variable and may sometimes reach as far down as pelvis.
Relations of transverse colon:
- Greater omentum
- Umbilical and hypogastric regions of anterior abdominal wall
- Second part of the duodenum
- Head of the pancreas
- Coils of jejunum
Blood supply of transverse colon:
The transverse colon receives its blood supply from two different sources. The proximal two thirds (lying towards the right colic flexure) are supplied by the medial colic artery, which is a branch of the superior mesenteric artery. The distal third (lying towards the left colic flexure) is supplied by the left colic artery, which is a branch of the inferior mesenteric artery.
Thus the transverse colon receives its blood supply from both superior and inferior mesenteric arteries.
The veins correspond to the arteries. Those from the proximal two thirds drain into the superior mesenteric vein and those from the distal third drain into the inferior mesenteric vein.
Lymph drainage of transverse colon:
As was the case with blood supply, the lymph drainage is also in two parts. The lymph from the proximal two thirds drain into the superior mesenteric nodes, via the colic nodes. On the other hand, the lymph from the distal third drains into the inferior mesenteric nodes, via the colic nodes.
Nerve supply to transverse colon:
The proximal two thirds of ascending colon are innervated by sympathetic and parasympathetic nerves from the superior mesenteric plexus. The distal third in innervated by sympathetic and parasympathetic fibers from the inferior mesenteric plexus.