Chapter 13 Peripheral Nervous system

Sensory nervous system

- contains receptors,

- transmits information from receptors to the CNS

Somatic sensory

receives sensory information from skin, fascia, joints, skeletal muscles, special sense

Visceral sensory

recives sensroy information from viscera

Motor nervous system

- transmit information from NS to the rest of the body

- sends motor information to effectors

somatic motor

"voluntary" nervous system: innervates skeletal muscle

Autonomic motor

"involuntary" nervous system: innervates cardiac muscle, smooth muscle, glands

Olfactory nerve

sensory: smell

Optic nerve

Sensory: vision

Oculomotor nerve

Motor: eye muscles

Trochlear nerve

Motor: eye muscles

Trigeminal nerve

Sensory: facial skin

Motor: eyeball, chewing

Abducens nerve

Motor: eye muscles

Facial nerve

Sensory: facial expression

motor: taste, tear and salvia production

vesitbulocochlear nerve

sensory: equilibrium and hearing

glossopharyngeal nerve

Sensory: taste

Motor: swallowing, speech, salvia

Vagus nerve

Sensory: viscera

motor: including heart and lungs

Accessory nerve

Motor: speech, movement of head and shoulders

Hypoglossal nerve

motor: swallowing, speech

Anterior root

carries somatic and visceral motor signals from CNS to skeletal muscles and gland cells

Posterior root

carries sensory signals from PNS to the spinal cord

Posterior ramus

carry sensory signals from sensory receptors in the PNS to the spinal cord

Anterior ramus

Carry somatic motor signals from the CNS to skeletal muscles

ramus communicans

carries visceral motor signals from the ANS to organs of the ventral body cavity

Spinal nerve

carries visceral motor, somatic motor, and sensory signals to and from the spinal cord

Spinal Nerve Plexuses

- cervical, brachial, lumbar, sacral plexus

- merged networks or anterior rami

peripheral nerves

branch from plexuses

cervical plexus

C1-C5

Brachial plexus

C5-T1

Lumbar plexus

L1-L4

sccral plexus

L4-S4

Cervical nerves

C1-C8

thoracic nerves

T1-T12

lumbar nerves

L1-L5

Sacaral nerves

S1-S5

Coccygeal nerve

Co1

Visceral( autonomic) reflex

- usually connected with ANS

F: regulates body functions such as respiration, digestion

Example: pupilary light reflex( pupils dilate)

Somatic reflex

- somatic sensory and somatic motor neurons involved ( skeletal muscles)

F: prevents muscle/ tissue damage and maintains posture, balance, locomotion

Simple stretch reflex

- returns muscle to its optimal length after stretching

example: patellar (knee-jerk)

flexion reflex & crossed extenstion reflex

- withdraws affected limb from painful stimulus; simultaneous with crossed-extension reflex- contraction of extensor muscles of opposite limb

example: lift the heel of broken glass while balancing on the other leg

Golgi tendon reflex

-causes muscles to lengthen in response to increased muscle tension( relaxes to prevent damage)

example: drop a heavy weight

crainal nerve reflex

gag and corneal blink

sensor receptor

muscle spindle = stretch receptor in muscle detect stimulus and trigger action potential

Afferent (sensory ) neuron

conducts action potential to CNS/ integration center

integration center

action potential passes between neurons in brainstem or in spinal cord

efferent ( motor) neuron

conducts action potential to effector; 2 nerves

1. stimulates muscle

2. shuts of opposing muscle

effector ( muscle or gland)

Receives action potential and performs work