How it works
This digestive tract tissue layers diagram cuts the tube straight across to show its four layers round the lumen. A second view enlarges a block of the wall to show what each layer is made of.
Read the full guide
Correctly label the following tissues of the digestive tract
Work outward from the lumen. The mucosa lines it; the submucosa carries the vessels; the muscularis is the thick double band of muscle; the serosa is the thin outer coat, continuous with the mesentery.
Inside each layer
The mucosa is three tissues: epithelium on the surface, lamina propria under it, and the thin muscularis mucosae. The submucosa holds blood vessels and the submucosal plexus. The muscularis has an inner circular layer and an outer longitudinal layer, with the myenteric plexus between them.
- Two names start with muscularis. The muscularis mucosae is the thin band inside the mucosa; the muscularis is the thick third layer.
- Each plexus is named for where it lies: submucosal in the submucosa, myenteric between the muscle layers.
Questions and answers
What are the four layers of the digestive tract?
From the lumen outward: the mucosa, the submucosa, the muscularis and the serosa. The same four run the whole length of the tract, with details that change to fit each organ.
What is the difference between serosa and adventitia?
Both are the outermost layer. The parts of the tract inside the abdominal cavity have a serosa. Above the diaphragm, the esophagus has an adventitia instead.
Where are the myenteric and submucosal plexuses?
The myenteric plexus lies between the inner circular and outer longitudinal layers of the muscularis and controls movement. The submucosal plexus lies in the submucosa and regulates digestive secretions.
Which way do the muscle fibers run in the muscularis?
In the inner layer the fibers run round the tube. In the outer layer they run along its length. The stomach has a third, oblique layer.