Muscular layer

Muscular layer

LAYERS (Muscular layer includes the 2nd through 4th layers): serosa longitudinal muscle myenteric plexus circular muscle submucosal plexus submucosal mucosal

Transverse section of ureter.
Latin	tunica muscularis

The muscular coat (muscular layer, muscular fibers, muscularis propria, muscularis externa) is a region of muscle in many organs in the vertebrate body, adjacent to the submucosa membrane. It is responsible for gut movement such as peristalsis.

It usually has two distinct layers of smooth muscle:

inner and "circular"
outer and "longitudinal"

However, there are some exceptions to this pattern.

In the stomach and colon, there are three layers to the muscularis externa.
In the upper esophagus, part of the externa is skeletal muscle, rather than smooth muscle.

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

in the pyloric stomach, it forms the pyloric sphincter
in the anal canal, it forms the anal sphincter

Additional images

External links

muscular+layer at eMedicine Dictionary
Histology at nhmccd.edu
Bioweb at UWLAX Muscularis externa of the colon
Bioweb at UWLAX Smooth muscle layers of the gut
Histology at OU 52_05 - "Duodenum"
Organology at UC Davis Digestive/mammal/system1/system7 - "Mammal, whole system (LM, Low)"
UIUC Histology Subject 23
Histology at BU 11601ooa - "Muscle Tissue: smooth muscle, muscularis externa"
Histology at BU 10802loa - "Digestive System: Alimentary Canal - esophagus "

Anatomy of torso, digestive system: Gastrointestinal tract, excluding mouth (TA A05.3–7, TH H3.04.02-04, GA 11.1141)

Upper GI

Hypo- pharynx	Piriform sinus spaces: Peripharyngeal space Retropharyngeal space Parapharyngeal space Retrovisceral space Retropharyngeal space Danger space Prevertebral space Pterygomandibular raphe Pharyngeal raphe Buccopharyngeal fascia Pharyngobasilar fascia Pharyngeal muscles

Esophagus	UES LES Esophageal glands Serosa / Adventitia Muscular layer Submucosa Mucosa Muscularis mucosa

Stomach	by region: Greater curvature Lesser curvature Angular incisure Cardia Body Fundus Pylorus Pyloric antrum Pyloric canal by layer: Serosa Muscular layer Pyloric sphincter Submucosa Gastric mucosa Muscularis mucosa Gastric rugae Gastric pits Gastric gland Cardiac glands Fundic glands Pyloric glands Goblet cell

Lower GI

Intestine: small

Layers	Serosa Subserosa Muscular layer Circular folds Submucosa Mucosa Muscularis mucosa Peyer's patches Intestinal villus Intestinal gland

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

Jejunum	no substructures

Ileum	Terminal ileum Ileocecal valve

Intestine: large

Layers	Serosa Subserosa Muscular layer Submucosa Mucosa

Cecum	Vermiform appendix

Colon	ascending colon hepatic flexure transverse colon splenic flexure descending colon sigmoid colon continuous taenia coli haustra epiploic appendix

Rectum	Transverse folds of rectum Rectal ampulla

Anal canal	Anal columns Anal valves Anal sinuses Pectinate line Sphincter ani internus muscle Intersphincteric groove Sphincter ani externus muscle Anus

M: DIG

anat(t, g, p)/phys/devp/enzy

noco/cong/tumr, sysi/epon

proc, drug(A2A/2B/3/4/5/6/7/14/16), blte

Anatomy: urinary system (TA A08, TH H3.06, GA 11.1215)

Abdomen

Kidneys

Layers	Renal fascia • Renal capsule • Renal cortex (Renal column) • Renal medulla (Renal sinus, Renal pyramids, medullary interstitium) • Renal lobe • Cortical lobule • Medullary ray • Nephron

Intrarenal arteries	(Renal artery) → Segmental arteries → Interlobar arteries → Arcuate arteries → Interlobular arteries → Afferent arterioles

Renal tubule	Renal corpuscle (Glomerulus, Bowman's capsule) → Proximal tubule → Loop of Henle (Descending, Thin ascending, Thick ascending) → Distal convoluted tubule → Connecting tubule → Collecting ducts aka Duct of Belini → Renal papilla → Minor calyx → Major calyx → Renal pelvis

Intrarenal veins	Efferent arterioles → Peritubular capillaries / Vasa recta → Arcuate vein → Interlobar veins → (Renal vein)

JGA	Macula densa • Juxtaglomerular cells • Mesangium/Extraglomerular mesangial cell

Filtration	Glomerular basement membrane • Podocyte • Filtration slits • Mesangium/Intraglomerular mesangial cell • Tubular fluid

Ureters

Orifice of ureter • Adventitia • Muscular layer • Mucosa

Pelvis

Bladder	Apex • Uvula • Neck • Median umbilical ligament • Muscular layer (Trigone • Detrusor) • Mucosa • Submucosa

Urethra	Urethral sphincters (External sphincter muscle of male urethra, External sphincter muscle of female urethra, Internal sphincter muscle of urethra)

M: URI

anat/phys/devp/cell

noco/acba/cong/tumr, sysi/epon, urte

proc/itvp, drug (G4B), blte, urte

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.