The brain and spinal cord communicate with the body Via cranial nerves and spinal nerves. These nerves are part of the peripheral nervous system which conveys sensory information to the central nervous system and conveys messages from the central nervous system to the body's muscles and glands.
Spinal Nerves (Somatic Nervous System)
The spinal nerves begin at the junction of the dorsal and ventral roots of the spinal cord. The nerves leave the vertebral column and travel to the muscles or sensory receptors they innervate, branching repeatedly as they go. Branches of spinal nerves often follow blood vessels, especially those branches that innervate skeletal muscles. The cell bodies of all axons that bring sensory information into the brain and spinal cord are located outside the CNS. (The sole exception is the visual system; the Retina of the eye is actually a part of the brain). These incoming axons are referred to as Afferent Axons because they "bear toward" the CNS. The cell bodies that give rise to the axons that bring somatosensory information to the spinal cord reside in the Dorsal Root Ganglia, rounded swellings of the dorsal root. These neurons are of the Unipolar type.
Cell bodies that give rise to the ventral root are located within the gray matter of the spinal cord.
Cranial Nerves
Twelve pairs of cranial nerves leave the ventral surface of the brain. Most of these nerves serve sensory and motor functions of the head and neck region. one of tenth or Vagus Nerve, regulates the functions of organs in the thoracic and abdominal cavities. It is called the vagus (wandering) nerve because its branches wander throughout the thoracic and abdominal cavities. (The word Vagabond has the same root).
Several forms of sensory information are received through cranial nerves. These nerves convey somatosensory information from the head and neck region, information concerning taste from the tongue, auditory information and information concerning balance from the ears, visual information from the eyes, and information concerning smell from nose.
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