All of the following are part of the mucosal layer of the digestive tract at the esophagus EXCEPT ________.
a. lamina propria
b. epithelial cells
c. muscularis externa
d. nonkeratinized stratified squamous cells
e. All are found in the mucosa of the esophagus
This question did not get revised. I used this exact question during a review session and roughly 90% of the students (roughly 40-50) got it wrong even though it is such a low level question. The correct answer is 'c'. The student responses were split between lamina propria and nonkeratinized stratified squamous cells. This really surprised me. The 4 main layers of the digestive tract at the esophagus are the mucosa, submucosa, muscularis externa, and the serosa. Within the mucosa there are epithelial cells (nonkeratinized stratified squamous cells are a form of the epithelial tissue found there), lamina propria, and the muscularis mucosae. It appears that the students are mistaking the muscularis externa for the musclaris mucosae. I think this question aligned nicely with both the Caldwell paper and the Beatty et al. paper in that it addresses a seemingly common misconception.
