Study guide

CNS

brain and spinal cord; processes and integrates information

PNS

all nerves outside CNS; connects CNS to limbs and organs

Neuromotor system

CNS+PNS components that controls coordinated movement

Cell body

contains nucleus

dendrites

receive signals; many per neurons

axon

transmits signals; one per neuron

axon hillock

summation point for voltage signals

sensory (afferent)

unpolar; send into to cns 

motor (efferent)

alpha motor neurons (skeletal muscles); gramma motor neurons (intrafusal fibers)

motor unit

alpha motor neuron + all muscles fibers it innervates

motor unit functions

all fibers contract when neurons fires

motor unit principles

all - or-none activation

Central nervous system structures

• cerebrum

• diencephalon

• Cerebellum

• brain stem

• spinal cord

Cerebrum 

voluntary movement 

diencephalon

thalamus: relay station; attention, mood

hypothalamus: endocrine control, homeostasis

cerebellum

smooth movement, coordination, posture, motor learning

Brain stem

• pons: chewing,balance 

• medulla: breathing, internal regulation 

• midbrain: sensory motor integration 

Spinal cord

gray matter: cell bodies

dorsal horns: sensory

ventral horns: motor (alpha motor neurons)

stroke (CVA)

sudden neurological deficit due to ischemia or hemorrhage

Types of stroke ( ischemic)

83%

atherothrombotic, embolic, lacunar, cryptogenic

Types of stroke (hemorrhagic)

17%

intracerebral, subarachnoid

Stroke risk factors

atherosclerosis, HTN, cardiac disease, diabetes

stroke pathophysiology

anoxia→infarction→edema→ increase ICP → herniation

stroke syndromes 

ACA, MCA, PCA, vertebrobasilar

stroke symptoms

• aphasia

• sensory/motor deficits

• spasticity

• abnormal reflexes

stroke diagnosis 

• dopller 

• CT

• MRI

• Angiography

• EKG

Recovery stage of stroke 

1. flaccidity 

2. spasticity & synergies 

3. voluntary movement in synergies

4. isolated joint control 

5. movement out of synergy 

6. near normal control 

Warning signs for strokes

1. sudden weakness

2. confusion

3. vision loss

4. dizziness

5. headache

Traumatic brain injury

brain insult from external force

Primary Damage of traumatic brain injury 

1. diffuse axonal injury: shearing of axons 

2. focal injury: contusions, hemorrhages

3. coup-contrecoup: impact + rebound injury

Secondary damage of traumatic brain injury

1. hypoxic ischemic injury 

2. edema, increase ICP 

Concussion

temporary brainstem dysfunction

Changes in traumatic brain injury

physical: motor, speech, seizures

cognitive: memory, attention, aphasia

behavioral: mood swings, impulsivity

Diagnosis for brain injury

CT, MRI, EEG

Recovery stages for brain injury

coma→vegetative→minimally responsive→ confusion→ independence→ competence→ plateau

Degenerative disorder overview

MS, ALS, PD, MG: each affect nervous system differently

Multiple sclerosis (MS)

demyelinating CNS disease; autoimmune 

Types of MS

1. relapsing- remitting (65%-80%)

2. primary progressive (10-20%)

3. secondary progressive

4. progressive relapsing

MS symptoms 

1. paresthesia 

2. ataxia

3. vertigo

4. fatigue

5. spasticity 

6. vision loss

MS diagnosis 

1. MRI 

2. EEG 

3. EMG

Amyotrophic lateral sclerosis (ALS)

degeneration of UMN + LMS

types of ALS

Progressive muscular atrophy (LMN)

primary lateral sclerosis (UMN)

progressive bulbar palsy

ALS symptoms

weakness

fasciculations

spasticity

dysphagia

dysarthria

Parkinson’s disease

Dopamine deficiency in basal ganglia 

hypokinetic disorder

Symptoms of Parkinson’s disease

tremor, ridity (lead-pipe/cogwheel), bradykinesia, postural instability, festination gait, speech changes

Myasthenia gravis (MG)

autoimmune attack on ACh receptors

MG symptoms

• fatigue 

• facial droop 

• chewing/swallowing difficulty

worsens with activity, improves with rest

Types of MG

• ocular

• mild generalized

• sever generalized

• crisis

Peripheral nervous system (PNS)

connects CNS to limbs/organs

PNS motor sensory receptors

input

PNS motor units 

output

PNS receptors 

Exteroceptors: external stimuli

interoceptors: internal stimuli

proprioceptors: body position/ movement 

Sensory receptors

Free nerve ending: pain/temp

merkel discs, root hair plexuses: light touch

meissner’s corpuscles: light touch (hairless skin)

ruffini’s, pacinian corpuscles: deep pressure, stretch, vibration

proprioceptors

• muscle spindles: stretch

• golgi tendon organs: tension

• joint kinesthetic receptors: joint position

• info sent to cerebellum and spinal reflex arcs

Motor unist 

motor neuron + all innervated fibers

all fibers contract together 

fine control: fewer fibers per neuron 

Cranial and spinal nerves

• mnemonic: oily oranges on tower tickle ants funnily and give velvety angry hands

• 31 spinal nerves: 8C, 12T, 5L, 5S, 1C

• dorsal roots: sensory

• ventral roots: motor

• rami: branches outside foramen

• plexuses: cervical, brachial, lumbar, sacral

• Brachial plexus (C5-T1): musculocutaneous, median, ulnar, axillary, radial

Peripheral nerve injuryies

cause: trauma, compression, metabolic, inflammation, surgery, aging

common injuries:

• radial (most common)

• ulnar (30%)'

• median (15%)

• lumbosacral plexus (3%)

Classification of nerve injuries 

Neurapraxia: temporary; full recovery 

axonotmesis: axonal damage: regeneration possible 

neurotmesis: complete severance; surgical repair needed

specific nerve injuries & deformities

• median: ape hand (thumb adduction, hyperextended index)

• ulnar: claw hand

• radial: wrist drop (extensor weakness)

• thoracodorsal: wining of scapula

• lateral popliteal: foot drop

Treatment and repair

Screening:

• ulnar: tip of little finger

• median: tip of index finger

• radial: thumb extension

surgical pns

epineural 

fascicular 

nerve graft 

repair failure for pns

inadequate resection

tension

Pain

• IASP: sensory/emotional experience linked to tissue damage

• subjective; varies by individual

• nociception: detection via A-delta

• C fibers

Physiology of pain 

components:

• detection (nociceptors)

• activation (stimulus)

• transmission (neural pathway)

• modulation (inhibition/ amplification)

Pain classification

Acute: < 6 months; injury/inflammation 

chronic: > 6 months; may lack clear cause 

Pain Type

nociceptive: proportional; protective

inflammatory: tissue damage

neuropathic: CNS/PNS dysfunction; non-protective

psychogenic: psychological origin

mixed: combo (failed back surgery)

Pain pathway

• fast pain: A-delta→ spinothalamic→ reticular formation→ thalamus→ hypothalamus→ limbic system

• Slow pain: C fibers→ spinothalamic→ reticular formation→ thalamus→ hypothalamus→ limbic system

Pain modulation (inhibition)

gate control theory: large fibers (A-apha, A-beta) inhibit small fibers (A-delta, C)

descending analgesic system: endorphins/enkephalins inhibit pain via presynaptic inhibition 

pain and gender

gender role theory: women more likely to report pain

exposure theory: women face more pain risks

vulnerability theory: women more