Final answer:
The 12 cranial nerves in humans handle sensory input and motor output for the head and neck, with some nerves dedicated to sensory functions, some to motor, and some performing both. The cranial nerve exam tests these nerves to diagnose potential neurological issues.
Step-by-step explanation:
Cranial Nerves Overview
Humans possess 12 cranial nerves that perform a variety of sensory and motor functions. Three of the nerves are exclusively sensory, five are purely motor, and four have a mix of sensory and motor fibers. The sensory nerves, such as the olfactory (smell) and optic (vision) nerves, transmit sensory information to the brain. The motor nerves, like the oculomotor nerve, control muscle movements in areas like the eyelids and eyeballs. The mixed nerves, including the glossopharyngeal nerve, can perform both functions, such as transmitting taste sensations (sensory) and controlling the act of swallowing (motor).
The cranial nerve exam is a diagnostic tool that assesses the health and function of these nerves, providing insights into possible brain stem or neurological damage based on the performance of sensory and motor tasks.