Muscular layer

Muscular layer
Histological section of the ureter, showing the thick muscular layers surrounding the lumen.
Details
Latin	tunica muscularis
*Anatomical terminology* [edit on Wikidata]

Gastrointestinal wall

This article is one of a series on the
General structure Epithelium Mucosa Submucosa Circular muscle Longitudinal muscle Serosa Adventitia
Specific Meissner's plexus Auerbach's plexus
Organs Esophagus Stomach Intestines

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:

inner and "circular"
outer and "longitudinal"

However, there are some exceptions to this pattern.

In the stomach there are three layers to the muscularis externa.
In the upper esophagus, part of the externa is skeletal muscle, rather than smooth muscle.
In the vas deferens of the spermatic cord, there are three layers: inner longitudinal, middle circular, and outer longitudinal.
In the ureter the smooth muscle orientation is opposite that of the GI tract. There is an inner longitudinal and an outer circular layer.

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

in the pylorus of the stomach, it forms the pyloric sphincter
in the anal canal, it forms the internal anal sphincter

References

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

External links

Muscularis externa of the colon - BioWeb at University of Wisconsin System
Smooth muscle layers of the gut - BioWeb at University of Wisconsin System
UIUC Histology Subject 23
Histology image: 11601ooa – Histology Learning System at Boston University — "Muscle Tissue: smooth muscle, muscularis externa"

Anatomy of the Gastrointestinal tract, excluding the mouth

Upper

Pharynx	Muscles Spaces peripharyngeal retropharyngeal parapharyngeal retrovisceral danger prevertebral Pterygomandibular raphe Pharyngeal raphe Buccopharyngeal fascia Pharyngobasilar fascia Piriform sinus

Esophagus	Sphincters upper lower glands

Stomach	Curvatures greater lesser Angular incisure Cardia Body Fundus Pylorus antrum canal sphincter Gastric mucosa Gastric folds Microanatomy Gastric pits Gastric glands Cardiac glands Fundic glands Pyloric glands Foveolar cell Parietal cell Gastric chief cell Enterochromaffin-like cell

Lower

Small intestine

Microanatomy	Intestinal villus Intestinal gland Enterocyte Enteroendocrine cell Goblet cell Paneth cell

Duodenum	Suspensory muscle Major duodenal papilla Minor duodenal papilla Duodenojejunal flexure Brunner's glands

Jejunum	no substructures

Ileum	Ileocecal valve Peyer's patches Microfold cell

Large

Cecum	Appendix

Colon	Ascending colon Hepatic flexure Transverse colon Splenic flexure Descending colon Sigmoid colon Continuous taenia coli haustra epiploic appendix

Rectum	Transverse folds Ampulla

Anal canal	Anus Anal columns Anal valves Anal sinuses Pectinate line Internal anal sphincter Intersphincteric groove External anal sphincter

Wall

Anatomy of the urinary system

Kidneys

Layers

Circulation

Arteries
Veins

Nephron

Renal corpuscle	Glomerulus Bowman's capsule Glomerular basement membrane Podocyte Filtration slits Mesangium Intraglomerular mesangial cell

Renal tubule	Proximal convoluted tubule Loop of Henle Descending Thin ascending Thick ascending Distal convoluted tubule Connecting tubule Collecting ducts Tubular fluid Renal papilla Minor calyx Major calyx Renal pelvis

Juxtaglomerular apparatus	Macula densa Juxtaglomerular cells Mesangium Extraglomerular mesangial cell

Ureters

Bladder

Urethra

This article is issued from Wikipedia - version of the 10/7/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.