Muscular layer

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Muscular layer
Histological section of the ureter, showing the thick muscular layers surrounding the lumen.
Latin tunica muscularis
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.


It usually has two layers of smooth muscle:

  • inner and "circular"
  • outer and "longitudinal"

However, there are some exceptions to this pattern.

The inner layer of the muscularis externa forms a sphincter at two locations of the alimentary canal:


This article incorporates text from a public domain edition of Gray's Anatomy.

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