PNS pt 1

somatic peripheral nerves

mix of sensory, autonomic, and motor axons. cutaneous branches supply the skin but aren’t totally sensory, and muscular branches which are purely motor

large myelinated axons innervate

efferent extrafusal mm fibers, afferent spindles and GTO

medium myelinated axons innervate

efferent intrafusal mm fibers, afferent spindles, touch, vibration, skin stretch and pressure receptors

small myelinated axons innervate

efferent presynaptic autonomic, afferent nociceptive, temp, and visceral

unmyelinated axons innervate

efferent post synaptic autonomic, and afferent nociceptive temp, and visceral receptors

cervical plexus

anterior rami c1-c4, provides cutaneous sensory info from post scalp to clavicle, innervated anterior neck mm and diaphragm

brachial plexus

anterior rami c5-t1, entire upper limb is innervated, TOS

lumbar plexus

anterior rami L1-L4. innervated the skin and mm of anterior and medial thigh

sacral plexus

anterior rami of s1-s4, innervated posterior thigh and most of leg and foot, contains parasympathetic axons

movement and nerve health

promote blood flow throughout and promotes axoplasm to thin and flow more easily

motor unit

the nerve and mm fibers it innervates, synapse at neuromuscular junction, sufficient acetylcholine is released to initiate action potentials in mm fibers

myasthenia gravis

an autoimmune disease that damages ACh receptors at the neuromuscular junction, from repeated use of mm leads to increasing weakness, no cure

botulism

a neurotoxin that enters the body causing interference with the release of ACh from the motor axon, produces acute, progressive weakness, loss of stretch reflex, sensation remains

hyperalgesia

increased sensitivity to pain from a stimulus that normally provokes pain

dysesthesia

sending mixed signals to the brain of sensations that aren’t there

paresthesia

burning or prickling sensation (pins and needles, falling asleep)

allodynia

pain due to a stimulus that doesn’t normally elicit pain

denervation autonomic changes (single nerve)

signs are usually observed only if the nerve is completely severed

denervation autonomic changes (many nerves)

problems may include difficulty regulating BP, HR, sweating, bowel and bladder functions and impotence

denervation trophic changes

mm atrophy, skin becomes shiny, nails brittle, subcutaneous tissues thicken, poor healing of wounds and infection, joint damage

mononeuropathy

involves single nerve and considered a focal dysfunction

multiple mononeuropathy

involves several nerves and multifocal (asymmetrically involves individual nerves)

polyneuropathy

involves many nerves and is a generalized disorder that typically has distal and symmetrical presentation

GBS

polyneuropathy, more on motor system than sensory, paresis worse proximally, rapid onset, progressive paralysis, require ventilator

hereditary motor and sensory neuropathy (charcot-marie-tooth disease)

paresis of mm distal to knee, foot drop, steppage gate, frequent tripping, mm atrophy, affects dorsiflexors

meninges

layers of connective tissue that surround the spinal cord, continuous with meninges that surround the brain

layer of meninges that surround the spinal cord (outer to inner)

dura (tough), arachnoid (separate from pia by CBSF) and pia (adhere to spinal cord surface

internal structure of the spinal cord

dorsal horn (sensory), lateral horn (autonomic), ventral horn (motor)

ventral root

coalescence of ventral rootlets, efferent motor root of a spinal nerve bringing info away from spinal cord

dorsal root

splits into dorsal rootlets, afferent sensory info of a spinal nerve bringing info to the spinal cord

during a slump test, if there is decrease knee extension, what could that indicate

tension in the neural structures, created by stretch of the meninges and peripheral nerve connective tissue

the SLR assesses what and what’s a positive

assesses neural tension, stretches sciatic and tibial nerve, generates tension in the lumbosacral trunk, stretches the cuada equina during hip flexion

stepping pattern generators

adaptable neural networks that produce rhythmic output, performed unconsciously once it becomes rhythmic

if stimulus occurs at the onset of the swing phase, the tib anterior activity what ?

increases

if stimulus occurs at the end of the swing phase, the tib anterior activity what?

decreases and antagonist mm activity increases