Cranial nerves are the nerves that emerge directly from the brain (including the brainstem). They form part of the peripheral nervous system. There are 12 cranial nerves, several of which are important for speech and hearing. Cranial nerves arise from the brain and, with only one exception, distribute their fibers to the head and neck. These nerve transmit sensory and motor impulses, only sensory impulses, or only motor impulses. Sensory-afferent: impulses toward the brain. Motor-efferent: impulses away from the brain. Damage to any of the cranial nerves involved in speech production can cause weakness, hypotonia, or any other factor that can cause dysarthria. A quick screen of function of cranial nerves involved in speech is a useful part of any motor speech disorder exam.
This section contains a further description of the cranial nerves as well as several functional assessments.