Central and Peripheral Nerves

Spinal Cord

Gray Matter White Matter

Spinal Cord White Matter White Matter –Myelinated and Unmyelinated fibers –Made of Ascending and Descending tracts –Ascending – Sensory pathways –Descending – Motor pathways

Spinal Cord Gray Matter Gray Matter –H-shaped in center of spinal cord –Dorsal Horn  Sensory receptor site –Ventral Horn  Somatic motor neurons

Spinal Cord Dorsal root ganglion Dorsal root ganglion –Formed by afferent fibers carrying impulses from receptors Ventral root Ventral root –Very short –Fuse to form spinal nerves

Peripheral Nervous System All nervous tissue outside the brain and spinal cord All nervous tissue outside the brain and spinal cord Composed as Sensory and Motor Composed as Sensory and Motor

Nerves Three types of nerves Three types of nerves –Sensory  Nerves that conduct impulses to the CNS –Motor  Nerves that transmit impulses away from CNS –Mixed  Nerves that both conduct impulses to the CNS and away from the CNS

Cranial Nerves Olfactory – Smell Olfactory – Smell Optic – Vision Optic – Vision Oculomotor – Motor function and parasympathetic fibers, serve eye Oculomotor – Motor function and parasympathetic fibers, serve eye Trochlear – Motor functions, serve eye Trochlear – Motor functions, serve eye Trigeminal – General sensation, motor function, serve forehead, check and jaw Trigeminal – General sensation, motor function, serve forehead, check and jaw Abducens – Motor function, serve eye Abducens – Motor function, serve eye

Olfactory I Optic II Oculomotor III Trochlear IV Trigeminal V Abducens VI Facial VII Auditory (vestibulocochlear) VIII Glossopharyngeal IX Vagus X Spinal Accessory XI Hypoglossal XII

Facial – Taste, motor function, parasympathetic fibers Facial – Taste, motor function, parasympathetic fibers Vestibulocochlear – Hearing and balance Vestibulocochlear – Hearing and balance Glossopharyngeal – Taste, motor function, parasympathetic fibers Glossopharyngeal – Taste, motor function, parasympathetic fibers Vagus – Serve internal organs Vagus – Serve internal organs Accessory – Motor functions, muscle of neck Accessory – Motor functions, muscle of neck Hypoglossal – Motor, serves tongue and jaw Hypoglossal – Motor, serves tongue and jaw

Plexus A plexus is the lateral joining of spinal nerves A plexus is the lateral joining of spinal nerves

NameOrigin Major Nerve Cervical Deep in neck under sternocleido- mastoid Phrenic nerve which connects to the diaphram Brachial Located partially in the neck and axillary area Axillary nerve which supplies upper limb Lumbar Arises from 1 st 4 lumbar spinal Femoral nerve, lower limb Sacral Arises from spinal L4-S4 Sciatic, largest & longest in lower body