Kaplan Nursing Entrance Practice Exam

Which muscles are involved in bending a joint at an acute angle?

1. Skeletal Muscles

2. Flexor

3. Extensor

4. Cardiac Muscle

The correct answer is: Flexor

The correct answer is flexor muscles. These muscles are specifically designed to bring two body parts closer together by decreasing the angle of the joint between them. For instance, when bending your elbow to bring your forearm closer to your upper arm, the flexor muscles (located on the anterior side of the upper arm) contract, facilitating this movement. In contrast, skeletal muscles are a broader category that includes both flexor and extensor muscles. While skeletal muscles play a role in joint movement, they don’t specifically indicate the action of bending at an acute angle as flexors do. Extensor muscles perform the opposite function by increasing the angle of the joint when they contract. For example, they straighten the arm at the elbow, thus they are not involved in the action of bending the joint at an acute angle. Cardiac muscle is a specialized muscle found in the heart, responsible for pumping blood throughout the body. It is not involved in the movement of limbs or joints, thus making it unrelated to the process of bending joints. Therefore, flexors are the specific type of muscles required for bending joints, which aligns with the question about creating an acute angle.