Final answer:
To assess motor function of the cervical spine, practitioners use tests such as flexion and extension of the neck and shoulder shrugs against resistance to evaluate strength and symmetry, which are indicative of the functional integrity of muscles innervated by the accessory nerve.
Step-by-step explanation:
The motor function of the cervical spine is typically tested through a series of movements that assess the strength and function of muscles, particularly those innervated by the accessory nerve such as the sternocleidomastoid and trapezius. By asking a patient to flex and extend the neck or shrug the shoulders against resistance, a practitioner can test the muscle strength and pinpoint potential deficits. The test may involve lateral flexion of the neck toward the shoulder, actively engaging both muscles to detect any asymmetry or weakness on one side, which could indicate damage or neuromuscular impairment. Additionally, the motor exam involves an inspection for structural irregularities and an assessment of muscle tone, checking for hypotonicity or flaccidity that might suggest issues with lower motor neuron function.
Movement disorders can occur due to changes in muscle tissue, and ruling out structural anomalies is an initial part of the motor exam. This comprehensive examination is a major section of the neurological exam that assesses both sensory and motor functions related to the spinal cord, including the dorsal and ventral regions, to help localize spinal damage.