Longitudinal muscular layer of small intestine
Stratum musculare longitudinale intestini tenuis
- Latin synonym: Stratum longitudinale tunicae muscularis intestini tenuis; Stratum helicoideum gradus longi
- Synonym: Longitudinal layer of muscular coat of small intestine; Long pitch helicoidal layer
- Related terms: Longitudinal layer; Long pitch helicoidal layer
Definition
Longitudinal muscular layer of small intestine forms the outer component of the muscularis externa and consists of smooth muscle fibres arranged parallel to the long axis of the intestinal tube. It lies external to the inner circular muscle layer, with the myenteric (Auerbach's) plexus situated between the two layers.
Function
Contraction of the longitudinal muscle layer shortens segments of the intestine and works in coordination with the circular muscle layer to generate peristaltic waves that propel intestinal contents towards the large intestine. Together, these muscle layers also contribute to segmentation movements, which mix chyme with digestive secretions and enhance contact between nutrients and the absorptive mucosal surface.
The coordinated activity of the longitudinal and circular muscle layers is essential for normal gastrointestinal motility, and disruption of their function or their neural control can result in intestinal motility disorders.
References
Collins JT, Nguyen A, Omole AE, et al. Anatomy, Abdomen and Pelvis, Small Intestine. [Updated 2025 Feb 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459366/
Standring, S. (2015) Grays Anatomy: The Anatomical Basis of Clinical Practice. 41st edn. London: Churchill Livingstone Elsevier. Chapter 65, Small intestine.
