From the esophagus to the anal canal, the walls of every organ of the alimentary canal are made up of the same four basic layers. Arrange them in order from the lumen.
A) muscularis externa, serosa, mucosa, and submucosa
B) serosa, mucosa, submucosa, and muscularis externa
C) submucosa, serosa, muscularis externa, and mucosa
D) mucosa, submucosa, muscularis externa, and serosa

Question

Quizplus · Accepted Answer

The mucosa, which is in direct contact with the lumen, is the innermost layer, followed by the submucosa, muscularis externa, and serosa (or adventitia, depending on the location in the body). Therefore, the correct order is mucosa, submucosa, muscularis externa, and serosa, which is represented by choice D.

From the Esophagus to the Anal Canal, the Walls of Every