The lamina muscularis mucosae (or muscularis mucosae) is a thin layer (lamina) of muscle of the gastrointestinal tract, located outside the lamina propria and separating it from the submucosa. It is present in a continuous fashion from the esophagus to the upper rectum (the exact nomenclature of the rectum’s muscle layers is still being debated). A discontinuous muscularis mucosae–like muscle layer is present in the urinary tract, from the renal pelvis to the bladder; as it is discontinuous, it should not be regarded as a true muscularis mucosae.
Section of duodenum of cat. X 60. (Muscularis mucosae labeled at right, third from the top.)
|Latin||Lamina muscularis mucosae|
In the gastrointestinal tract, the term mucosa or mucous membrane refers to the combination of epithelium, lamina propria, and (where it occurs) muscularis mucosae. The etymology suggests this, since the Latin names translate to "the mucosa's own special layer" (lamina propria mucosae) and "muscular layer of the mucosa" (lamina muscularis mucosae).
The muscularis mucosae is composed of several thin layers of smooth muscle fibers oriented in different ways which keep the mucosal surface and underlying glands in a constant state of gentle agitation to expel contents of glandular crypts and enhance contact between epithelium and the contents of the lumen.
Section of the human esophagus. Moderately magnified.
- H.G. Burkitt et al., Wheater's Functional Histology, 3rd ed.
- aplab[dead link] - BioWeb at University of Wisconsin System
- Histology image: 14_08 at the University of Oklahoma Health Sciences Center — "Lung"
- Essentials of Human Physiology by Thomas M. Nosek. Section 6/6ch1/s6ch1_11.
- Anatomy photo: digestive/mammal/system1/system4 - Comparative Organology at University of California, Davis - "Mammal, whole system (LM, Low)"
- UIUC Histology Subject 830
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