Physical Therapy Assistant Practice Exam

A physical therapist assistant works with a patient with a C6 spinal cord injury. Which muscle would NOT be innervated due to this level of injury?

1. Biceps muscle

2. Deltoid muscle

3. Triceps muscle

4. Diaphragm

The correct answer is: Triceps muscle

A patient with a C6 spinal cord injury retains some function in upper extremities but experiences significant functional limitations due to the level of the injury. At the C6 level, the biceps and deltoid muscles are innervated, allowing for flexion at the elbow and some shoulder movement. The diaphragm is also innervated from higher cervical nerves (C3 to C5), so respiratory function is typically intact in these patients. However, the triceps muscle, which is responsible for elbow extension, is primarily innervated by the radial nerve that arises from the C7 spinal nerve. Since the C6 spinal cord injury does not allow for the innervation of the C7 nerve root, the triceps muscle would not be functional for this patient. Therefore, the inability to innervate the triceps muscle is accurately reflected by identifying it as the muscle that would NOT be innervated due to the C6 spinal cord injury.