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

Compared to the ileum, the jejunum has more valvulae conniventes and fewer folds per unit length. Like the ileum, normal jejunal wall thickness is less than 3 mm. The jejunum has a smaller diameter (average 2.5 cm) compared to the ileum (3 cm).

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

  • jejunal branches from the superior mesenteric artery
  • corresponding veins which drain into the superior mesenteric vein
  • lymphatics drain into the superior mesenteric lymph nodes
  • sympathetic: lateral horn cells of spinal segments T9 and T10
  • parasympathetic: vagus nerve augments peristaltic activity

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

Anatomy: Abdominopelvic
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Article information

rID: 23082
Section: Anatomy
Synonyms or Alternate Spellings:
  • Jejunal anatomy

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