Peripheral Nervous System

Peripheral Nervous System

Nervous system that refers to all the nerves outside the brain and the spinal cord

Acts as a communication network between the CNS to the rest of the body

Sends motor impulses away from CNS and toward the EFFECTORS

Nerves

Bundles of neuron fibers/axons found outside of CNS

• Myelinated

• Protected by three connective tissue coverings

  • Epineurium

  • Perineurium

  • Endoneurium

Epineurium

Outermost layer that surrounds the entire nerve

Perineurium

Extends inwards from Epineurium which divides nerves into fascicles

Endoneurium

Innermost Layer which wraps around EACH INDIVIDUAL axon

Ganglia

Cluster of Neuron Cell Bodies located outside the CNS

• relay and processing centers for nerve signals travelling from/to CNS

• Usually Unmyelinated (more Cell body, less axon)

Cranial Nerve I

Name: Olfactory

Type: Sensory

Function: Smell

Cranial Nerve II

Name: Optic

Type: Sensory

Function: Sight/Vision

Cranial Nerve III

Name: Oculomotor

Type: Motor, Parasympathetic 

Function: Motor - upper eyelid and 4 extrinsic eye muscles | Contracts pupil and thickens lens

Cranial Nerve IV

Name: Trochlear

Type: Motor

Function: Moves one extrinsic eye muscle

Cranial Nerve V

Name: Trigeminal

Type: Sensory, Motor

Function: Sensory to face and teeth, Motor to muscles of mastication (chewing)

Cranial Nerve VI

Name: Abducens

Type: Motor

Function: Moves one extrinsic eye muscle

Cranial Nerve VII

Name: Facial

Type: Sensory, Motor, Parasympathetic

Function: Sensory - Taste, Motor - Muscles of facial expression, Parasympathetic - saliva and tear glands

Cranial Nerve VIII

Name: Vestibulocochlear

Type: Sensory

Function: Hearing and Balance

Cranial Nerve IX

Name: Glossopharyngeal

Type: Sensory, Motor, Parasympathetic

Function: Sensory - Taste, motor - Pharyngeal Muscle, Parasympathetic - Saliva gland

Cranial Nerve X

Name: Vagus

Type: Sensory, Motor, Parasympathetic

Function: Sensory - Larynx, Pharynx, and Viscera, Motor - Digestion

Cranial Nerve XI

Name: Accessory

Type: Motor

Function: Neck and back muscles

Cranial Nerve XII

Name: Hypoglossal

Type: Motor

Function: Tongue Muscles

Spinal Nerves

• 31 pairs

• all nerves are mixed

• emerge from spinal cord via ventral and dorsal roots.

• 8 cervical, 12 thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal

Nerve Plexus - Cervical

C1 - C4

neck, shoulder, Diaphragm

Phrenic Nerve

Nerve Plexus - Brachial

C5 - T1

shoulder, arm, forearm, hand

Axillary, Musculocutaneous, Median, Radial, Ulnar

Nerve Plexus - Lumbar

L1 - L4

Lower abdomen, anterior thigh

Femoral, Obturator

Nerve Plexus - Sacral

L4 - S4

Buttocks, posterior thigh, leg, foot

Sciatic

Nerve Plexus - Coccygeal

S4 - Co1

Skin around coccyx & anus

Anococcygeal nerve