nervous system

what does the somatosensory system do

awareness of body sensation - touch, temperature, position, pain

what are the 3 types of sensory neurons

general somatic: pain, touch, temp

special somatic: muscles, tendons, joints

general visceral: fullness, discomfort

difference between first, second, and third order neurons

first: periphery to CNS, sensory

second: spinal cord to thalamus, ascending in dorsal column

third: thalamus to cortex, processing

what is this

central sulcus

what is this

sylvian/lateral fissure

where is the precentral gyrus and what is its main job

anterior to central gyrus, primary motor cortex

where is the postcentral gyrus and what is its main job

posterior to central gyrus, somatic sensation

sensory info from limbs and trunk share what common structure

dorsal root ganglion neurons

what is part of the sensory unit

body of dorsal root ganglion, peripheral branch, central axon

what are the 3 types of nerve fibers

A: myelinated - touch, pressure, heat, cold pain

B: myelinated - cut/subcut mechanoreceptors

C: unmyelinated - mechanical/chemical/intense hot or cold pain, warm/hot sensation - delayed transmission

UE dermatomes C5-T2

C5 deltoid, C6 thumb, C7 middle finger, C8 pinky, T1 M epicondyle, T2 axilla

LE dermatomes L1-S2

L1 inguinal ligament, L2 distal M quad, L3 M epicondyle, L4 M malleolus, L5 third MTP, S1 calcaneus, S2 popliteal fossa

facial dermatomes CN5

V1 frontal bone, V2 maxilla, V3 mandible

important thoracic dermatomes

T4 nipple line, T10 umbilicus

where does all general sensation and pain enter the spinal cord

dorsal root

describe the discriminative pathway

dorsal column, medial lemniscus

type A fibers, mechanoreceptors - somatosensory input ascends ipsilaterally, crosses over at medulla

spatial orientation, discrimination, delicate touch, joint position

first, second, and third order neurons of discriminative pathway

first: primary dorsal root ganglion - projects to dorsal column

second: dorsal column neuron - axon through M lemniscus

third: thalamic - projects axons to primary sensory cortex

what happens after an association neuron (3ON discriminative) is damaged

can feel and describe, cannot identify

describe the anterolateral pathway

spinothalamic tracts

type C fibers, free nerve endings

input crosses over at the spinal cord, ascends contralaterally

pain, temperature, crude touch, pressure

difference between lateral and anterior spinothalamic tracts

lateral: contralateral pain, temp, crude touch - fibers cross immediately in spinal cord

anterior: contralateral crude touch, pressure - most fibers ascend a few levels before crossing over, some fibers do not cross at all

when do anterolateral fibers synapse

before reaching thalamus in reticular formation of spinal cord

what happens in a brown sequard lesion

one side of spinal cord is lesioned - lose ipstlateral fine touch, contralateral pain and temperature

what is the point of the homunculus

proportion of cortex dedicated to peripheral areas

what happens with an anterior cerebral artery lesion

weak LE

lose sensation of genitals, foot, ankle

what happens with middle cerebral artery lesion

weak and lost sensation in face and UE

what happens with posterior cerebral artery lesion

impaired vision

why does referred pain from the viscera happen

not much cortex for pain perception in viscera, stimulus confused by different areas

difference between broca and wernicke’s areas

broca: speech production, near motor cortex

wernicke: speech understanding, near auditory cortex

what happens in the prefrontal cortex

reasoning, logic, decision making

difference between somatic and special senses

somatic: touch, pressure, temperature, proprioception

special: requires complex sensory organs - vision, hearing, smell

what is 2 point discrimination an early indicator of

neuropathy and healing

where is the highest and lowest acuity for 2 point discrimination

highest: lips, cheek, fingertips

lowest: back, upper arm

what do free nerve endings detect

pain perception, touch, temperature

what do meissner corpuscles detect? where are they? adaptation rate?

light movement over skin, vibration

in hairless parts of skin

quick, fraction of second

what do merkel disks detect? where are they? adaptation rate?

steady state sensation to touch (like clothes)

dome shaped receptors on skin

stimulus starts strong, diminishes slowly

what does a pacinian corpuscle detect? where is it? adaptation rate?

deep pressure changes, tissue vibration - should stimulate with palpation

subcutaneous area and fascia

quick, hundredths of a second

what does a hair follicle end organ detect? where is it? adaptation rate?

movement on body surface

unmyelinated fibers around hair follicle

quick

what do ruffini end organs detect? where are they? adaptation rate?

deformation (heavy/continuous pressure)

joint capsules, skin, deeper structures

little adaptation

what happens (neurologically) with diabetes

chronic high blood sugar damages nerves → diabetic neuropathy, lose ability to sense pain

what weight monofilament is considered the threshold for protective sensation

5.07

what does someone that cannot feel the 5.07 monofilament need to do

regular foot checks for breakdown, lesions, blisters, etc

what temperatures do warmth receptors detect

25-46 C

77-114 F

what temperatures do cold receptors detect

10-30 C

50-104 F

what temperatures are thermal pain receptors stimulated at

<10 C or >46 C

why can getting in a hot tub feel painful

receptors detect CHANGES - strong stimulus can be perceived as painful

will adapt slowly

describe when the 2 proprioceptors are active and what their result is

golgi tendon organs: catching 300 lbs - quick tension or load on muscle → loosen or give out as protection

muscle spindle receptors: DTRs - quick lengthening of muscle → shorten as protection

what are tonic proprioceptors for?

phasic proprioceptors?

tonic: limb positioning - orient, info at rest and movement

phasic: kinesthesia - triggered by change in position

what happens in sensory adaptation? what receptors adapt quickly/slowly

magnitude and rate of conduction of impulse decreases

touch receptors: quick

proprioceptors: slow

when is desensitization therapy commonly performed

amputations, CRPS (complex regional pain syndrome)

describe desensitization therapy

start with soft material stimulus, progressively rougher

frequently throughout day → decrease pain sensation in hypersensitive region

describe the gold standard treatment for BPPV (benign paroxymal positional vertigo)

habituation - repeated exposure, maneuver to slowly move stones back to inner ear

describe the gate control theory

pain fibers are slower and smaller, stimulate larger and faster fibers to temporarily block pain sensation (close the gate)

outdated, pain is more complex

describe the 2 types of nociceptors

A Delta: acute, myelinated - somatic pain, sharp/intense pain from superficial trauma

C fibers: chronic, unmyelinated - visceral pain, dull/aching pain originating from viscera

what can you educate your patient about pain?

what can pain education do for a patient?

pain is more than just tissue damage. it’s like an alarm - you have more control over pain than you think

decreased risk of chronic pain, healthcare costs, and pain catastrophization

what are 2 big factors that contribute to pain

anxiety and stress

describe acute pain

activated nociceptors at site of local tissue damage - short duration, associated with anxiety

what psychological factor plays a role in chronic pain behavior

depression

difference between cutaneous and deep somatic pain

cutaneous: sharp, burning - localized or dermatomal

deep: diffuse - originates from deep structures

describe visceral pain

low density of nociceptors → pain is referred

travels along pathways of autonomic nervous system

describe how referred pain happens

deep structures have little nociceptors → pain felt by area innervated by the same spinal segment, location of pain is misinterpreted

where is referred pain of the heart

T1-T5

T1: medial epicondyle

T2: axilla

jaw in females

where is referred pain of the kidney

thick band around abdomen

3 ways pain is often quantified by patients

numeric pain intensity: 0-10

visual analog scale: straight line 10cm long, mark pain level

verbal descriptor scale: ranked words to evaluate pain

how to manage acute vs chronic pain

acute: aggressive, pain meds before symptoms are severe

chronic: preventative, noncurative methods if not treatable illness

cognitive-behavioral interventions for pain management

more effective if enacted before pain starts

relaxation, distraction, cognitive reappraisal, imagery, meditation, biofeedback

physical/infared agents of pain management

heat: vasodilation, increased extensibility, reduced tension on nociceptive nerve endings

cold: vasoconstriction to prevent fluid pooling in tissues, reduce afferent activity

what kind of infared therapy shows benefit for pain

contrast therapy (alternating hot and cold)

what is the result of a cold plunge

reduced protein synthesis, inhibit hypertrophy

stimulus induced analgesia for pain management

foundation in gate control theory, TENS estim, placed directly over painful area or in dermatome

acupuncture for pain management

reduce spasm, LACK HIGH QUALITY EVIDENCE

neurostimulation for pain management

low volt estim directly to spinal cord or targeted peripheral nerve

blocks pain sensation

may be surgically implanted

difference between COX 1 and 2

1: maintain stomach acidity, vasodilation

2: local tissue inflammation, vasoconstriction

what is an NSAID?

what can happen with overuse?

non steroidal anti-inflammatory drug

GI bleeding

what adverse events can happen with COX2 inhibitors

block vasoconstriction, small clots move straight to heart

adverse cardiac events in 4-6 weeks

describe the 2 nonnarcotic analgesics

aspirin/NSAIDs: block pain impulses, block both COX enzymes, anti-inflammatory

acetaminophen: like aspirin but not anti-inflammatory

describe opioid analgesics

aka narcotics, morphine-like actions

relieve short term pain or manage severe long term pain

when are opioids most effective

before pain starts or before pain becomes extreme

fewer doses associated with early return to daily activity pain free

what kind of responses do opioids cause? what cranial nerves are affected?

parasympathetic - pinpoint pupils, aletred mental status, decreased HR RR and BP, n/v, constipation

3, 7, 9, 10

opioid withdrawal effects

uncomfortable, mot life threatening

dilated pupils, flu like symptoms, rhinorrhea, joint pain, hypertension, n/v, cramps

what needs to happen with opioid intoxication

naloxone/narcan as antagonist if RR dangerously decreased

5 minutes intramuscularly, within 2 minutes intravenously

what can help ween off opioid use

methadone

what are the 2 neurotransmitters released from autonomic neurons

antagonists - norepinephrine, acetylcholine

describe the 2 types of adrenergic receptors and what they cause

bind norepinephrine

alpha: stimulatory, vasoconstriction

beta: inhibitory, vasodilation

what do beta receptors cause in the HEART

stimulatory, increase HR

what do beta blockers do

block beta receptor, block norepinephrine

decrease HR and BP

where is norepinephrine released from?

what kind of receptors?

adrenergic fibers - post ganglionic sympathetic neurons

beta and alpha receptors

describe the 2 types of cholinergic receptors and what they cause

bind acetylcholine

nicotinic: preganglionic neuron (symp and parasymp)

muscarinic: post gangiolic parasymp → bronchoconstriction

where is acetylcholine released from?

what kind of receptors

cholinergic fibers - preganglionic sympathetic neurons, pre and post ganglionic parasympathetic neurons

nicotinic and muscarinic

where are nicotinic receptors found?

muscarinic?

beta and alpha?

nicotinic: preganglionic sympathetic and parasympathetic

muscarinic: post ganglionic parasympathetic

beta nad alpha: post ganglionic sympathetic

what is trigeminal neuralgia

aka tic douloureux

stabbing pain from compression, inflammation, or degeneration of CN5

how is trigeminal neuralgia treated

tegretol relieves in most cases

can surgically remove trigeminal ganglion if severe → permanent loss of sensation in face, teeth, gums

what is postherpetic neuralgia? how does it present

herpes zoster, shingles - chicken pox stays dormant in dorsal root ganglia

presents with dermatomal rash, intermittent shooting pain

how is shingles treated

zostavax vaccine → 60% protection

antivirals: acyclovir, valacyclovir

what are dorsal root ganglia

peripheral sensory cell bodies

what is the biggest conern for a secondary headache

TBI, tumor

symptoms of a migraine headache

Pulsatile, photophobia, phonophobia

One day

Unilateral pain

Nausea/vomiting

Dysfunctional, debilitating, dark room

difference between migraines with and without aura

with: 25%, 5-60min flickering vision

without: 75%, no warning sign

how does a migraine work

hyperexcited part of the brain

starts at occipital lobe to cause spotty vision

cortical spreading anteriorly to cause aura

what can trigger onset of a migraine

estrogen, MSG, milk chocolate, cheeses

how does vasoconstriction and dilation affect a migraine

vasodilation around trigeminal nerve → nerve compressed → trigger

vasoconstriction from caffeine or SSRI → eased symptoms