Difference Between Jejunum and Ileum Anatomy

Difference between Jejunum and Ileum Anatomy: The jejunum and ileum are two parts of the small intestine, which is the digestive system's longest segment. They are in charge of nutrient absorption from partly digested food that enters the small intestine from the stomach. 

Jejunum Anatomy

  • It starts in the upper left quadrant of the abdomen.
  • Blood flow is provided by the superior mesenteric artery.
  • Absorbs mostly carbs and proteins.
  • When compared to the ileum, the muscular wall is thicker.

Ileum Anatomy

  • It is located in the lower right quadrant of the abdomen.
  • The superior mesenteric artery branches also supply blood.
  • Primarily responsible for vitamin B12, bile salts, and nutritional absorption.
  • When compared to the jejunum, the muscular wall is thinner.

Difference between Jejunum and Ileum Anatomy:

Considering the jejunum and ileum are both important parts of our bodies, let's look at the difference between Jejunum and Ileum Anatomy.





The jejunum is shorter, typically about 2/5 of the total length of the small intestine.

The ileum is longer, constituting the remaining 3/5 of the small intestine.


The jejunum has a larger diameter compared to the ileum.

The ileum has a smaller diameter compared to the jejunum.

Vascular Arcades

Vascular arcades (arterial arches) are more numerous and prominent in the jejunum.

Vascular arcades are less numerous and less prominent in the ileum.


The jejunum has a reddish colour due to a richer blood supply.

The ileum appears paler due to a relatively reduced blood supply.

Plicae Circulares

Plicae circulares (circular folds) are larger and more numerous in the jejunum.

Plicae circulares are smaller and less numerous in the ileum.

Fat Deposition

There is less fat deposition in the mesentery of the jejunum.

There is more fat deposition in the mesentery of the ileum.

Muscle Thickness

The muscular wall of the jejunum is thicker.

The muscular wall of the ileum is thinner.

Absorption Function

Primarily responsible for the absorption of carbohydrates and proteins.

Primarily responsible for the absorption of vitamin B12, bile salts, and additional nutrients.

Mesenteric Attachment

The mesentery attachment is less mobile in the jejunum.

The mesentery attachment is more mobile in the ileum.

Lymph Nodes

The jejunum has fewer lymph nodes.

The ileum has more lymph nodes.

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What is jejunum Anatomy?

The jejunum, which emerges from the duodenum and is appropriately titled "empty" in Latin, begins the small intestine's absorption functions. This 2.5-meter stretch of muscle features enormous folds called plicae circulares and small finger-like extensions called villi. These anatomical wonders enhance the surface area for nutrition absorption substantially, assuring optimal efficiency. The jejunum, which is rich in digestive enzymes and transporters, rapidly accepts carbs, proteins, and lipids into the circulation, powering our every motion.

Key characteristics of Jejunum Anatomy:

  • Jejunum is found in the upper abdomen.
  • It has thicker walls than the ileum.
  • The plicae circulares are bigger and more frequent.
  • It has a greater number of blood vessels.
  • A considerable fraction of nutrients, including carbs and proteins, are absorbed by this enzyme.

What is Ileum Anatomy?

The ileum is the longest part of the small intestine, reaching roughly 3 metres along the digestive highway. While the ileum has a similar shape to the jejunum, it specialises in absorbing finer information. Vitamins, minerals, and bile acids, which are often disregarded but are essential for health, make their way here. Notably, the ileum contains Peyer's patches, which are specialised lymphatic tissue clusters required for immunological activity. Finally, the ileum terminates in the ileocecal valve, which protects the portal to the large intestine and ensures unidirectional flow.

Key characteristics of Ileum Anatomy:

  • Ileum is found in the lower abdomen.
  • It has thinner walls than the jejunum.
  • Plicae circulares are smaller and fewer in number.
  • There are fewer blood vessels.
  • Absorbs bile salts and vitamin B12 that the jejunum does not.
  • It terminates at the ileocecal valve and links to the cecum of the large intestine.

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Similarities between Jejunum and Ileum Anatomy:

  • The jejunum and ileum are both found in the abdominal cavity and link the stomach to the large intestine.
  • They are two successive segments of the small intestine, with the jejunum at the proximal end and the ileum at the distal end. They make up the vast bulk of the small intestine.
  • Peristalsis occurs in both segments and aids in the flow of chyme (partially digested food) through the small intestine.
  • The superior mesenteric artery branches deliver blood to both the jejunum and the ileum.
  • The enteric nervous system, which regulates the gastrointestinal tract, innervates both segments.
  • The jejunum and ileum both feature multiple plicae circulares or valvulae conniventes.


What role do the jejunum and ileum play in nutrient absorption?

Both the jejunum and ileum are involved in the absorption of nutrients, such as carbohydrates, proteins, and fats. The jejunum primarily absorbs a significant portion of these nutrients, while the ileum absorbs bile salts and vitamin B12

How do the walls of the jejunum and ileum differ structurally?

The walls of the jejunum are thicker compared to the ileum. This structural difference is attributed to variations in muscle thickness and overall composition.

Is there a difference in the number of blood vessels supplying the jejunum and ileum?

Yes! The jejunum has more blood vessels compared to the ileum. The superior mesenteric artery branches supply blood to both segments, but the vascularity decreases as you move from the jejunum to the Ileum.

How do the crypts of Lieberkuhn differ between the jejunum and ileum?

The crypts of Lieberkühn, or intestinal glands, are present in both segments. However, the density and size of these glands may differ, with the jejunum often having a higher number.

What happens at the end of the ileum, and how is it connected to the large intestine?

The ileum ends at the ileocecal valve, marking the connection to the cecum of the large intestine. This valve regulates the flow of chyme from the small intestine into the large intestine.