Question

multiple choice question

which muscle compresses the anal canal, supports the uterus and other pelvic viscera, and aids in the falling away of the feces?

external anal sphincter
transverse abdominal
latissimus dorsi
levator ani

Explanation:

Identify the target muscle functions

The question asks for a muscle that performs three specific actions:

1. Compresses the anal canal.
2. Supports the pelvic viscera (including the uterus in females).
3. Aids in defecation (described as aiding in the falling away of the feces).

Evaluate the given options

Using the Pelvic Floor Muscles knowledge point

• External anal sphincter: This muscle surrounds the anal canal and keeps it closed, but it does not support the pelvic viscera like the uterus.
• Transverse abdominal: This is an abdominal wall muscle that compresses the abdomen, but it is not a pelvic floor muscle supporting the pelvic viscera directly.
• Latissimus dorsi: This is a large muscle of the back involved in shoulder movement.
• Levator ani: This is the principal muscle of the pelvic floor (pelvic diaphragm). It supports the pelvic viscera (such as the uterus, bladder, and rectum), resists increases in intra-abdominal pressure, and constricts the anal canal. During defecation, it elevates the pelvic floor and helps pull the anal canal up and over the fecal mass, aiding in the passage of feces.

Confirm the correct muscle

The levator ani muscle group (comprising the puborectalis, pubococcygeus, and iliococcygeus) perfectly matches all the functional descriptions in the prompt.

Answer:

• (A) External anal sphincter
• (B) Transverse abdominal
• (C) Latissimus dorsi
• (D) Levator ani (Correct answer)