Jejunum - Anatomy & Physiology

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Structure

Jejunum(Dog) - Copywright RVC 2008

• The jejunum is the longest part of the small intestine.
• It is highly coiled and occupies the ventral part of the abdominal cavity, filling those parts that are not occupied by other viscera. This produces species variation (see comparative aspects).
• It is suspended by the mesentry (mesojejunum). This conveys the blood vessels and nerves and houses lymph nodes.
  • The mesentry converges to its root. This is where the cranial mesenteric artery branches off from the aorta.

Function

• Has digestive and absorptive functions.

Vasculature

• The cranial mesenteric artery, a branch of the abdominal aorta, supplies blood to the jejunum.
• It branches greatly within the mesenty of the jejunum.
  • There are many anastomoses within the mesentry, which ensure that the intestine can survive even if a major division of the cranial mesenteric is damaged.
• The cranial mesenteric vein drains blood from the jejunum and enters the portal vein.
  • It is rich in the products of digestion following a meal.
  • The portal vein enters the liver.