This gastric illustration depicts the three layers of smooth muscle which line the stomach wall.
Smooth muscle in the stomach contracts during digestion, in order to break down nutrients. The muscle layers in the human stomach are each striated in different directions. Because smooth muscle can only contract in one direction, it is functionally adaptive for the stomach, which must contract as an organ overall, to contract in three directions. Another muscle in the body which has muscle fibers running in different directions is the tongue. The stomach is the only organ in the digestive system to have three muscle layers. The rest of the gastrointestinal tract, or GI tract, contains only two muscle layers.
The muscles together as a group, are called the muscularis externa.
Laura Maaske, B.Sc., M.Sc.BMC
Racine, WI 53402
Cell: (262) 308-1300
Text Copyright © Medimagery - Laura Maaske LLC
Illustration © 2000 Columbia Healthcare EHC, illustrated by Laura Maaske - Medimagery LLC.