Sensory Examination pt 1

damage to the primary motor area can cause

synergistic movement patterns

what other motor areas are found in frontal lobe?

primary motor area, premotor + supplementary motor areas

active screen tests

- rule in/out a problem in motor system

- pick up abnormal movements/weakness

- assists with differential dx

- can be used a systems review screen

purpose of sensory exam

- abnormalities in sensory process

- assists in finding a lesion

- guides treatment plan

sensory issues affect

motor learning

where does the deficit occur?

sensory receptor -> peripheral n -> spinal/cranial nn -> BS -> thalamus -> sensory cortex

what lobe of the sensory cortex does the deficit occur?

parietal, occipital, temporal

- based on info

***ALL SENSORY INFO STOPS AT THE

thalamus

exteroceptive sensory receptors

- superficial sensation

- info from ext environment

- pain, temp, touch, special senses

proprioceptive sensory receptors

- deep sensation

- info from mm, tendons, ligaments, joints, fascia

- position sense, vibration, movement awareness

what are interceptors (visceroceptors)?

receptors in internal organs

somatosensory =

superficial + deep

which somatosensory receptor responds to superficial light touch, movement across the skin and is a FAST-adapting receptor?

meissner's corpuscles

merkels discs

- superficial

- light touch, 2 pt discrimination

- small receptor field

- slow adapting

meissner's corpuscles

- superficial

- skin motion, touch

- small receptor field

- fast adapting

Pacinian corpuscles

- deep

- vibration, deep pressure

- large receptor fields

- fast adapting

Ruffini

- deep

- continuous pressure

- large receptor fields

- slow adapting

smaller the receptive field =

greater density of receptors, the greater the ability of brain to localize the stimulus site (2 pt discrimination)

where are proprioceptors located?

deep- muscle, tendon, joints

large diameter sensory afferents have the fastest conduction velocity. What sensory function travels on the fastest axon?

proprioception- need it to get to cerebellum, makes quick adjustments

is pain fast/slow

one of the slowest

proprioceptors

- deep sensations (musculoskeletal)

- sense of position + movement

three types of proprioceptors

1- mechanoreceptors

2- muscle spindles/GTOs

3- cutaneous mechanoreceptors

cutaneous mechanoreceptors

- Ruffini + pacinian corpuscles

- free nerve endings

function of proprioceptors

- maintain balance

- controlling limb movement

- evaluating shape of grasped objects

primary function of the muscle spindle

to detect changes in muscle length + initiate a reflex to resist overstretching

alpha vs gamma motor neurons

alpha- voluntary

gamma- causes the contraction

alpha + gamma always

co-contract

Where would you find a greater # of mm spindles- in the extra ocular mm or triceps mm?

eye mm -> more sensory movement

fast, fine movement =

more muscle spindles

patella reflex is an example of

a stretch reflex

patella reflex

1- tapping the patellar ligament stretches __________ and excites ______

2- ______ impulses travel the SC where synapses occur

3- the motor neurons send activating impulses to the ________ causing it to contract, ________

4- the _________ make inhibitory synapses with _________ neurons that prevent the ________ muscles from resisting quad contraction

1- quads, mm spindles

2- afferent (sensory)

3- quads, ext the knee

4- interneurons, ventral horn, antagonist

in this situation, from the quad response we want the hamstrings to be

inhibited

Golgi tendon organs- GTOS

detect changes in mm tension + stretch in tendons

autogenic inhibition

when muscle contracts

GTO info travels to what 3 places via the SC

- to inhibit the agonist

- to facilitate antagonist

- cerebellum for further proprioceptive FB

autogenic inhibition reflex has a greater role in

motor control

what factors increase nerve conduction velocity?

- axon diameter

- myelin

which fiber carries proprioception?

A alpha

which fiber carries touch/mechanoreceptors of the skin?

A beta

which fiber carries pain + temp?

A delta

which fiber carries temp, pain, itch?

C fibers

difference between large and small fibers?

large- proprioceptive

small- pain, autonomic

smaller afferent fibers (C + delta A) will synapse in the dorsal horn and travel to higher centers via what ascending tract?

ST

lateral ST carries info regarding

pain + temp

anterior (ventral) ST carries info regarding

light touch (crude) + pressure

anterolateral ST systems have what kind of fibers

- self protective

- slow conducting

- small diameter

ST 1st synapse crosses in the

dorsal horn

dorsal column- DCML carries info regarding

proprioception, vibration, localized/discriminatory (fine) touch

fasciculus gracilis vs cuneatus- carries info of

gracilis = LE

cuneatus = UE

spinocerebellar tract

carries info regarding unconscious somatosensory -> cerebellar

DCML 1st synapse

in dorsal horn + does NOT cross over

DCML crosses where?

medulla

primary somatosensory cortex

- S1

- size, shape, texture but can't identify object

secondary somatosensory cortex

- S2

- tactile learning + memory

lesion in S2 would cause

difficulty w/ tactile discrimination tasks- stereognosia

posterior parietal cortex (association)

- multimodal integration area (visual + motor)

- controls functional oriented visuomotor, object manipulation tasks, visual spatial performance

pathway from thalamus -> S1

thalamus -> mm spindles, superficial + deep skin, deep mm pressure

S1 -> S2 ->

to amygdala + hippocampus

or S1 ->

post parietal -> to motor + premotor cortex

feedforward control

- made in anticipation of a voluntary movement that is potentially destabilizing

- based on experience

feedback control

uses sensory info received during movement to monitor + adjust output

sensation loss + safety

- skin breakdown + pressure sores

- fall risk

patterns of sensory loss based on loc of lesion or Dx

- peripheral n

- nerve root

- SCI

- cortex (stroke)

- aging

- MS

peripheral n injury

neuropraxia

axonotmesis

neurotmesis

neuropraxia

- 1st degree

- focal n compression

- nerve contusion leading to reversible conduction block w/out degeneration

- good prognosis

axonotmesis

- 2nd degree

- axon + myelin sheath disruption -> conduction block w/ degeneration

- endoneurium intact

- fair to good prognosis

neurotmesis

- 3rd degree

- complete nerve division w/ endoneurium disruption

- no recovery unless surgery

peripheral n injuries can

regenerate

mononeuropathy

- 1 nerve

- meralgia paraesthetica, CTS

- lat fem cutaneous n

polyneuropathy

- mult nerves

- GBS, CIDP, CMT

- stocking glove

neuropathy on the thumb, index, and half of the middle finger

median n

neuropathy on the pinky side

ulnar n

neuropathy on the lateral aspect of the calf

lat + superficial peroneal n

neuropathy to the lateral aspect of the thigh

lateral femoral cutaneous n

can you have proprioception loss with a mononeuropathy?

no- every joint has innervation of multiple nerves

neuropathy to the dorsum side of thumb

radial n

peripheral neuropathy (polyneuropathy)

- longer nn fibers

- stocking glove

- DM, lupus, sarcoidosis, EtOH abuse, HIV, idiopathic

small fiber neuropathy

sensory (pain/temp) + ANS

- hyperalgesia, sweating, normal reflexes

- abnormal BF, slow healing

- wound healing/amputation

large fiber neuropathy

- proprioception, fine touch, vibration

- gait instability

- weakness, numbness

- fall concern

dermatome maps =

- area of skin inverted from one spinal n

- sensory pattern seen w/ cervical + lumbar radiculopathies

nerve root involvement

herniated disc or stenosis -> pressure on spinal n

complete SCI lesion- below lesion

- paralysis

- complete sensory loss

- inc reflexes + spasticity (UMN)

Brown-Sequard Syndrome

- isolated problem on one side of SC

- ipsilateral loss of motor (UMN) and position sense (DC tracts)

- contra pain + temp loss

why is there contralateral pain/temp loss?

bc crossed right away in SC

anterior cord syndrome

-- normal proprioception

- variable pain/temp loss

- variable motor

- DC tract preserved

posterior cord syndrome

proprioception loss, no UMN signs bc post cord only controls sensation

DCML + corticospinal cross at

medulla

what sensory maps are used for strokes?

homunculus

ACA

- minimal contra LE sensory loss

- weakness, urinary incontinence, gait apraxia

MCA

- contra UE + face sensory loss/weakness

- most common

left vs right CVA

left- Broca or wernike's aphasia

right- hemineglect, spatial deficits

PCA- peripheral vs central

peripheral- no sensory loss, visual deficits, visual agnosia

central- sensory loss all modalities or thalamic stroke (pain_

LEFT hemisphere stroke can cause

RIGHT hemiplegia/paresis

aphasia

RIGHT side sensory loss

RIGHT visual field neglect

diff reading, writing, calculating

apraxia

aware of deficits

RIGHT hemisphere stroke can cause

LEFT hemiplegia/paresis

neglect/defect of LEFT visual field

LEFT side sensory loss

extinction of left side stimuli

spatial disorientation

presentation of right hemisphere stroke

impulsive, poor judgement, poor insight

large cortical representation: what about receptor field size + density of receptors?

small = high density

lacunar infarcts

occlusion of deep penetrating AA with affect deeper brain structures

subcortical structures

internal capsule, BG, thalamus

internal capsule can be

pure motor + sensory

UE/face = LE