Physical Therapy Assistant Practice Exam

What is the expected innervation level for the triceps muscle?

1. C5-C6

2. C7-C8

3. C3, C4, C5

4. C5-T1

The correct answer is: C7-C8

The expected innervation level for the triceps muscle is primarily associated with the C7 and C8 nerve roots. The triceps brachii, located in the posterior compartment of the arm, is responsible for elbow extension and is innervated by the radial nerve, which originates from the brachial plexus. Specifically, the radial nerve derives its fibers from C7 and C8, which are crucial for the muscle's motor function. C7 is particularly important because it provides the primary innervating fibers that allow for the extension of the elbow. C8 also contributes to the innervation, helping with both the muscle's function and supporting movements. The triceps does not receive contributions from the other options listed, such as C5-C6, which correspond to shoulder and upper arm muscles, or C3, C4, which innervate the diaphragm and some shoulder muscles. Thus, the correct response aligns with the specific roles that C7 and C8 play in the function and innervation of the triceps muscle.