Anatomy and Physiology of the Hindgut Quiz

Focused SBA-style practice, followed by the answer and explanation for every question.

Free now: 5 questions
Full bank: 8 questions
Answers: Explained

Free question

Try one with the answer

A question from this quiz. Answer it to see the explanation students get.

Which structural feature of the large intestine is responsible for the formation of haustra?

A Presence of villi to increase absorptive surface area
B Incomplete external longitudinal muscle arranged as taeniae coli ✓
C Complete circular muscle layer forming plicae circularis
D Thickened mucosa forming permanent transverse folds
E Continuous longitudinal muscle layer along the colon

The answer is B: Incomplete external longitudinal muscle arranged as taeniae coli

Explanation

Why B is correct

See The Large Intestine. Option B is correct because the external longitudinal muscle of the colon is incomplete: instead of a continuous sheet, it is gathered into three bands called the taeniae coli. These bands are shorter than the colon itself, and their tonic (continuous low-level) contraction bunches the colon up, so the wall between the bands puckers out into sacs called haustra. The result is the typical segmented, pouched appearance of the large intestine. Haustra are different from the plicae circulares of the small bowel, which are permanent folds that cross the whole diameter of the lumen, while haustra do not. The colon also has crypts rather than villi, because its main jobs are the final absorption of water and electrolytes and the storage of faeces, not the absorption of nutrients.

Muscle layer: The external longitudinal muscle of the colon is incomplete.
Taeniae coli: The muscle is gathered into three bands that are shorter than the colon.
Pouching: Tonic contraction of the bands puckers the wall between them into haustra.

Why the other options are incorrect

A. Presence of villi to increase absorptive surface area: Villi are finger-like projections of the small intestine that increase surface area for absorption. The colon has crypts instead and has no villi. It would be correct for a question about the small bowel's lining.
C. Complete circular muscle layer forming plicae circularis: Plicae circulares are folds of the lining that belong to the small intestine, not muscle, and they are not made by a complete circular muscle layer. The colon has no such folds. It would be correct for a question about the small bowel's folds.
D. Thickened mucosa forming permanent transverse folds: Permanent transverse folds that cross the whole lumen describe the plicae circulares of the small intestine. Colonic haustra do not span the whole width. It would be correct for a question about the jejunum.
E. Continuous longitudinal muscle layer along the colon: A continuous longitudinal muscle layer would shorten the bowel evenly and would not make pouches. The colon's longitudinal muscle is incomplete and gathered into three bands. It would be correct for the small intestine, which has a continuous layer.

Easy

With Premium, questions you miss become Revision Coach flashcards, scheduled for review.

Question preview

What you will practise

More questions from this set. Start the quiz to answer them and see each explanation.

1
Which artery provides the principal arterial supply to the proximal rectum?
2
A patient with long-standing liver cirrhosis develops dilated veins around the rectum due to raised pressure in the veins that normally carry blood from the gut to the liver. Which anatomical feature of the rectum best explains why this region can act as a bypass between those veins and the general venous circulation?

Revise before you test

Review SimpleMed's doctor-written article, then return here to check recall.

Read the topic article

Need wider coverage?

Explore every Gastrointestinal System topic set, or build a tailored mixed session.

Browse subject quizzes