Muscular layer
Histological section of the ureter, showing the thick muscular layers surrounding the lumen.
Details
Identifiers
Latintunica muscularis
TA98A05.4.01.010
A05.5.01.021
A05.6.01.004
A05.7.01.004
A05.7.03.011
A05.7.04.009
A05.8.02.008
A08.1.05.010
A08.2.01.006
A08.3.01.010
A09.1.02.012
A09.1.04.010
A09.2.03.007
A09.3.05.009
A09.4.02.011
A09.3.06.003
A09.4.02.018
A09.4.02.027
Anatomical terminology

The muscular layer (muscular coat, muscular fibers, muscularis propria, muscularis externa) is a region of muscle in many organs in the vertebrate body, adjacent to the submucosa. It is responsible for gut movement such as peristalsis. The Latin, tunica muscularis, may also be used.

Structure

It usually has two layers of smooth muscle:

However, there are some exceptions to this pattern.

The inner layer of the muscularis externa forms a sphincter at two locations of the gastrointestinal tract:

In the colon, the fibres of the external longitudinal smooth muscle layer are collected into three longitudinal bands, the teniae coli.

The thickest muscularis layer is found in the stomach (triple layered) and thus maximum peristalsis occurs in the stomach. Thinnest muscularis layer in the alimentary canal is found in the rectum, where minimum peristalsis occurs.

Function

The muscularis layer is responsible for the peristaltic movements and segmental contractions in and the alimentary canal. The Auerbach's nerve plexus (myenteric nerve plexus) is found between longitudinal and circular muscle layers, it starts muscle contractions to initiate peristalsis.

References

Public domain This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)