muscularis externa

Examples of muscularis externa in the following topics:

• Muscularis

  • From the inside out they are called the mucosa, submucosa, muscularis externa, and serosa.
  • The muscularis externa consists of an inner circular layer and a longitudinal outer muscular layer.
  • The thickness of muscularis externa varies in each part of the tract.
  • Alone among the GI tract, the stomach has a third layer of muscularis externa.
  • The muscularis mucosa is adjacent to the submucosa, and should not be confused with the muscularis externa.

• Submucosa

  • From the inside out they are called: mucosa, submucosa, muscularis, and serosa .
  • The submucosa lies under the mucosa and consists of fibrous connective tissue, separating the mucosa from the next layer, the muscularis externa.
  • The muscularis in the stomach differs from that of other GI organs in that it has three layers of muscle instead of two.
  • The submucosa consists of a dense irregular layer of connective tissue with large blood vessels, lymphatics, and nerves branching into the mucosa and muscularis externa.
  • It contains Meissner's plexus, an enteric nervous plexus, situated on the inner surface of the muscularis externa.

• Microscopic Anatomy of the Stomach

  • This consists of an epithelium, the lamina propria underneath, and a thin bit of smooth muscle called the muscularis mucosae.
  • The submucosa lies under this and consists of fibrous connective tissue that separate the mucosa from the next layer, the muscularis externa.
  • The muscularis in the stomach differs from that of other GI organs in that it has three layers of muscle instead of two.
  • The muscularis externa is made up of three layers of smooth muscle.

• Enteric Nervous System

  • The myenteric (Auerbach's) plexus, located between the inner and outer layers of the muscularis externa.

• Anatomy of the Gallbladder

  • There are several different layers of the gallbladder: the mucosa (epithelium and lamina propria), the muscularis, the perimuscular, and the serosa.
  • The muscularis is a layer of smooth muscular tissue that helps the gallbladder contract and squirt its bile into the bile duct.
  • The perimuscular (meaning around the muscle) is a fibrous connective tissue layer that surrounds the muscularis.

• Histology of the Small Intestine

  • The small intestine wall has four layers: the outermost serosa, muscularis, submucosa, and innermost mucosa.
  • Serous fluid is a lubricating fluid that reduces friction from the movement of the muscularis.
  • The muscularis is a region of muscle adjacent to the submucosa membrane.
  • This image shows the layers of the duodenum: the serosa, muscularis, submucosa, and mucosa.

• Blood Vessel Structure

  • The outermost layer is the tunica externa or tunica adventitia, composed entirely of connective fibers and surrounded by an external elastic lamina which functions to anchor vessels with surrounding tissues.
  • The tunica externa is often thicker in veins to prevent collapse of the blood vessel and provide protection from damage since veins may be superficially located.
  • This diagram of the artery wall indicates the smooth muscle, external elastic membrane, endothelium, internal elastic membrane, tunica externa, tunica media, and tunica intima.

• Mucosa

  • From the inside out they are called: mucosa, submucosa, muscularis, and serosa.
  • The muscularis mucosae is a thin layer of smooth muscle and its function is still under debate.

• Artery Function

  • As with veins, arteries are comprised of three layers: the tunicae intima, media, and externa.

• Arteries, Veins, and Capillaries

  • Veins and arteries both have two further tunics that surround the endothelium: the middle, tunica media is composed of smooth muscle, while the outer tunica externa is connective tissue (collagen and elastic fibers).
  • Arteries and veins consist of three layers: an outer tunica externa, a middle tunica media, and an inner tunica intima.