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
The submucosa (or tela submucosa) is a thin layer of tissue in various organs of the gastrointestinal, respiratory, and genitourinary tracts. It is the layer of dense irregular connective tissue that supports the mucosa (mucous membrane) and j ...
. 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
The renal pelvis or pelvis of the kidney is the funnel-like dilated part of the ureter in the kidney. It is formed by the covnvergence of the major calyces, acting as a funnel for urine flowing from the major calyces to the ureter. It has a mucous ...
to the
bladder
The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine en ...
; as it is discontinuous, it should not be regarded as a true muscularis mucosae.
In the
gastrointestinal tract, the term ''mucosa'' or ''
mucous membrane
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
'' refers to the combination of
epithelium, lamina propria, and (where it occurs) muscularis mucosae.
[H.G. Burkitt et al., ''Wheater's Functional Histology, 3rd ed.''] 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
gland
In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream ( endocrine gland) or into cavities inside the body or its outer surface ( exocrine gland).
Structure
...
s in a constant state of gentle agitation to expel contents of glandular
crypts
A crypt (from Latin ''crypta'' "vault") is a stone chamber beneath the floor of a church or other building. It typically contains coffins, sarcophagi, or religious relics.
Originally, crypts were typically found below the main apse of a churc ...
and enhance contact between epithelium and the contents of the
lumen.
Additional images
Image:Gray1033.png, Section of the human esophagus. Moderately magnified.
Image:Gray1053.png, Section of mucous membrane of human stomach, near the cardiac orifice.
Image:Gray1082.png, Section of mucous membrane
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
of human rectum. X 60.
Image:Illu stomach layers.jpg, Layers of stomach wall
Image:Gut wall.svg, General structure of the gut wall showing the Muscularis mucosa.
References
Stacey E. Mills — Histology for Pathologists: 3rd (third) Edition, page 670.
External links
*
* — "Lung"
*
* - "Mammal, whole system (LM, Low)"
*
Membrane biology
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