Peripheral Nervous System

three layers of a peripheral nerve

epineurium, perineurium, endoneurium

Epinerium

- surrounds the entire nerve

- encloses nerve trunk (all ascending and descending nerves)

perineurium

- separates fascicles

- allows fascicles to glide independent of other fascicles

endoneurium

- separates axons into different types of sensory modality

1. sensory

2. motor

3. autonomic

peripheral nerves possess a high degree of resistance to what

ischemia

blood-nerve barrier

Similar to blood brain barrier. Found in PNS. Arises from perineurial cells in perineurium that surrounds a fascicle( a bundle of axons).

nerve gliding

movement optimizes the health of nerves by promoting the flow of blood throughout the nerves and the flow of axoplasm through the axons

afferent axons (Sensory)

carries information from peripheral receptors toward the CNS

efferent axons (motor)

carry information away from the CNS

neuromuscular junciton

a chemical synapse formed by the contact between a motor neuron and a muscle fiber

mechanoreceptors

respond to touch, pressure, vibration, stretch, and itch

chemoreceptors

respond to chemicals

thermorecepetors

respond to changes in temperature

photoreceptors

respond to light

nociceptors

pain receptors

free nerve endings

respond to pain and temperature

encapsulated endings

Class of receptors that respond to touch and internal movement

meissner's corpuscles

sensitive to shape and textural changes in exploratory and discriminatory touch

pacinian corpuscles

groups of corpuscles respond to pressure changes

- ex: grasping or releasing an object

golgi tendon organ

- responsive to active contraction of a muscle

- proprioception

muscle spindles

- responsive to stretch stimulus

- proprioception

ruffini endings

respond to stretch, touch, pressure, and vibration

nerve plexuses are formed by what rami

anterior rami

peripheral nerve injuries result in

- motor changes

- lost sensation and/or abnormal sensations

- autonomic changes