Central and Central and Peripheral NervesPeripheral Nerves

Spinal CordSpinal Cord

Gray Matter

White Matter

Spinal CordSpinal Cord

White MatterWhite Matter– Myelinated and Unmyelinated Myelinated and Unmyelinated

fibersfibers– Made of Ascending and Made of Ascending and

Descending tractsDescending tracts– Ascending – Sensory pathwaysAscending – Sensory pathways– Descending – Motor pathwaysDescending – Motor pathways

Spinal CordSpinal Cord

Gray MatterGray Matter– H-shaped in center of spinal H-shaped in center of spinal

cordcord– Dorsal HornDorsal Horn

Sensory receptor siteSensory receptor site– Ventral HornVentral Horn

Somatic motor neuronsSomatic motor neurons

Spinal CordSpinal Cord

Dorsal root ganglionDorsal root ganglion– Formed by afferent fibers carrying Formed by afferent fibers carrying

impulses from receptorsimpulses from receptors Ventral rootVentral root

– Very short Very short – Fuse to form spinal nervesFuse to form spinal nerves

Peripheral Nervous SystemPeripheral Nervous System

All nervous tissue outside the All nervous tissue outside the brain and spinal cordbrain and spinal cord

Composed as Sensory and Composed as Sensory and MotorMotor

NervesNerves Three types of nervesThree types of nerves

– SensorySensoryNerves that conduct impulses to the CNSNerves that conduct impulses to the CNS

– MotorMotorNerves that transmit impulses away from Nerves that transmit impulses away from CNSCNS

– MixedMixedNerves that both conduct impulses to the Nerves that both conduct impulses to the CNS and away from the CNSCNS and away from the CNS

Cranial NervesCranial Nerves Olfactory – SmellOlfactory – Smell Optic – VisionOptic – Vision Oculomotor – Motor function and Oculomotor – Motor function and

parasympathetic fibers, serve eyeparasympathetic fibers, serve eye Trochlear – Motor functions, serve eyeTrochlear – Motor functions, serve eye Trigeminal – General sensation, motor Trigeminal – General sensation, motor

function, serve forehead, check and jawfunction, serve forehead, check and jaw Abducens – Motor function, serve eyeAbducens – Motor function, serve eye

Olfactory IOptic IIOculomotor IIITrochlear IVTrigeminal VAbducens VIFacial VIIAuditory (vestibulocochlear) VIIIGlossopharyngeal IXVagus XSpinal Accessory XIHypoglossal XII

Facial – Taste, motor function, Facial – Taste, motor function, parasympathetic fibersparasympathetic fibers

Vestibulocochlear – Hearing and Vestibulocochlear – Hearing and balancebalance

Glossopharyngeal – Taste, motor Glossopharyngeal – Taste, motor function, parasympathetic fibersfunction, parasympathetic fibers

Vagus – Serve internal organsVagus – Serve internal organs Accessory – Motor functions, muscle Accessory – Motor functions, muscle

of neckof neck Hypoglossal – Motor, serves tongue Hypoglossal – Motor, serves tongue

and jawand jaw

PlexusPlexus

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

NameName OriginOrigin Major NerveMajor Nerve

CervicalCervicalDeep in neck Deep in neck

under under sternocleido-sternocleido-

mastoidmastoid

Phrenic nerve Phrenic nerve which connects which connects to the diaphramto the diaphram

BrachialBrachialLocated Located

partially in partially in the neck and the neck and axillary areaaxillary area

Axillary nerve Axillary nerve which supplies which supplies

upper limbupper limb

LumbarLumbar Arises from 1Arises from 1stst 4 lumbar 4 lumbar

spinalspinal

Femoral nerve, Femoral nerve, lower limblower limb

SacralSacral Arises from Arises from spinal L4-S4spinal L4-S4

Sciatic, largest Sciatic, largest & longest in & longest in lower bodylower body