Cranial Nerve Examination

A cranial nerve is a nerve attached directly to the brain or brainstem as compared to spinal nerves which are attached to the spinal cord. Each cranial nerve exists as a pair and is present on both sides of the brain and provides afferent and efferent innervation principally to the structures of the head and neck. Unlike spinal nerves, whose roots are neural fibres from the spinal grey matter, cranial nerves are composed of the neural processes associated with distinct brainstem nuclei and cortical structures. Unlike the spinal nerves, cranial nerve nuclei are functionally organized into distinct nuclei within the brainstem. Typically, the more posterior and lateral nuclei tend to be sensory, the more anterior tend to be motor (Fig. 13.1).