The muscularis mucosae (or lamina muscularis mucosae) is a thin layer ( lamina) of

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

of the

gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...

, located outside the

lamina propria The lamina propria is a thin layer of connective tissue that forms part of the moist linings known as mucous membranes or mucosae, which line various tubes in the body, such as the respiratory tract, the gastrointestinal tract, and the urogenital ...

, 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) an ...

. It is present in a continuous fashion from the

esophagus The esophagus (American English), oesophagus (British English), or œsophagus (Œ, archaic spelling) (American and British English spelling differences#ae and oe, see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), c ...

to the upper

rectum The rectum (: rectums or recta) is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. Before expulsion through the anus or cloaca, the rectum stores the feces temporarily. The adult ...

(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 convergence 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 bladder () is a hollow organ in humans and other vertebrates that stores urine from the kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the bladder is a distens ...

; as it is discontinuous, it should not be regarded as a true muscularis mucosae. In the

, 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 ...

'' refers to the combination of

epithelium Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...

, 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 A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...

s in a constant state of gentle agitation to expel contents of glandular crypts and enhance contact between epithelium and the contents of the lumen.

Additional images

Image:Gray1033.png, Section of the human

. Moderately magnified. Image:Gray1053.png, Section of mucous membrane of human stomach, near the cardiac orifice. Image:Gray1082.png, Section of

of human

. 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)" * {{Authority control Digestive system