Jejunum

The jejunum is arbitrarily defined as the proximal two-fifths of the small intestine and is, on average, about 3 m in length.

Gross anatomy

Compared to the ileum, the jejunum has more valvulae conniventes and fewer folds per unit length. Like the ileum, the normal jejunal wall thickness is less than 3 mm. The jejunum has a larger diameter compared to the ileum.

Relations

Together with the ileum, the jejunum lies in the free margin of the mesentery as a continuation of the duodenum.

Arterial supply

  • jejunal branches from the superior mesenteric artery

Venous drainage

  • corresponding veins which drain into the superior mesenteric vein

Lymphatic drainage

  • lymphatics drain into the superior mesenteric lymph nodes

Innervation

  • sympathetic: lateral horn cells of spinal segments T9 and T10
  • parasympathetic: vagus nerve augments the peristaltic activity

Radiographic features

Fluoroscopy
Small bowel follow-through examination (SBFT)

Jejunum has a delicate feathery appearance and is located in the left upper abdomen.