Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), in contrast to spinal nerves (which emerge from segments of the spinal cord). Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck.
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The Functional Components Cranial nerves act basically as either a one-way or a two-way road, meaning that some of them transmit information only to the brain (afferent), others only transmit instructions out (efferent), while the remainder are built to receive and transmit information. Following this, the cranial nerves that are exclusively or largely afferent are (I, II, and VIII), the others that are largely efferent are (III, IV, VI, XI, and XII), and the ones that contain both afferent and efferent fibers are (V, VII, IX, and X). The efferent fibers of the cranial nerves arise within the brain from groups of nerve cells termed motor nuclei. The afferent fibers arise outside the brain from groups of nerve cells, generally in a sensory ganglion along the course of the nerve. The central processes of these nerve cells then enter the brain, where they end in groups of nerve cells termed sensory nuclei. The four functional types of fibers found in spinal nerves are present also in some of the cranial nerves: somatic afferent, visceral afferent, visceral efferent, and somatic efferent. These four types are termed "general." In certain cranial nerves, however, components that are "special" to the cranial nerves are present. The special afferent fibers comprise visual, auditory, equilibratory, olfactory, taste, and visceral reflex fibers. (The first three are usually classified as somatic, and the last three as visceral.) The special efferent fibers (which are classified as visceral) are those to skeletal muscles either known or thought to be derived from the pharyngeal arches (muscles of mastication, facial muscles, muscles of pharynx and larynx, sternomastoid, and trapezius).
 The 12 Cranial NervesEnlarge by passing over or clickingimage info Original image attribution goes to Patrick J. Lynch; http://commons.wikimedia.org/wiki/File: Brain_human_normal_inferior_view.svg The cranial nerves may be grouped as follows:
The brainstem is the lower posterior extension of the brain, located in front of the cerebellum. Its superior or top portion, is the center for visual and auditory reflexes such as blinking and adjusting the ear to sound volume. The middle section, or the pons, bridges the cerebellum hemispheres and higher brain centers with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves. Which part of the brain primarily regulated muscle functioning and coordinates movement?Cerebrum. The cerebrum (front of brain) comprises gray matter (the cerebral cortex) and white matter at its center. The largest part of the brain, the cerebrum initiates and coordinates movement and regulates temperature.
Which part of the brain is primarily associated with life support and basic function of the body?The hindbrain includes the upper part of the spinal cord, the brain stem, and a wrinkled ball of tissue called the cerebellum. The hindbrain controls the body's vital functions such as respiration and heart rate.
Which part of the brain contains the central switchboard of the central nervous system CNS?Thalamus: Your thalamus is a structure residing deep in your cerebrum and above your brainstem. This structure is sometimes referred to as the switchboard of the central nervous system. It relays various sensory information, like sight, sound or touch, to your cerebral cortex from the rest of your body.
Which of the following areas of the brain controls voluntary movement of the eyes?The cortex is in overall control of 'voluntary' eye movement.
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Which part of the brain primarily regulates muscle functioning and coordinates movement?
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