Longitudinal Muscular Layer of Small intestine (Jejunum)
Stratum musculare longitudinale intestini tenuis
Read moreStructure/Morphology
The cross-sectional microarchitecture of the small intestine demonstrates mucosa, submucosa, and muscular (inner circular and outer longitudinal) layers with a thin outer serosal covering.
The longitudinal muscular layer forms the outer muscle fibers of the muscular layer and its fibers are smooth muscle cells which are oriented roughly parallel to the long axis of the digestive canal.
Related parts of the anatomy
Key Features/Anatomical Relations
The smooth muscle cells of the muscular layer are controlled by inputs from the vagus nerve and the myenteric nerve plexus. This plexus of enteric nerves sits between the circular layer and the outermost longitudinal layer of muscle fibers in the muscularis externa.
Function
The outer longitudinal muscular layer, together with the circular muscle layer, act to create rhythmic peristaltic contractions. This mixes chyme and pushes contents distally.
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Small Intestine
Atrophy of the small intestine and a proportional decrease in villus height and crypt depth occur due to a decrease in the rate of crypt cell growth, and the result is a decrease in total mucosal thickness (51).
