Huerta Exam 2: Sensation

sensation generally refers to:

auditory

gustatory

olfaction

somatosensory (touch)

vestibular (vision, ear, proprioception)

visual

what makes up the verstibular system?

(vision, ear, proprioception)

in this lecture we will mainly focus on:

somatosensory

primary somatosensory behaviors originate from what area of the brain?

the post central gyrus

postcentral gyrus

primary somatosensory cortex

primary motor commands are initiated in what area of the brain?

primary motor region

a maplike representation of regions of the body in the brain

homunculus

the primary somatosensory cortex is located in the

postcentral gyrus

areas of the body that get a lot of sensation

hands

lips

face

hot item of burner journey

1) painful stimulus

2) nociceptors fire

3) impulse is sent to spinal column

4) in column splits

- to muscle (reflex)

- to brain

Nociceptors

sensory receptors that enable the perception of pain in response to potentially harmful stimuli

A person with CNS injury with brain involvement, with or without spinal cord injury, is more likely to have deficits in

proprioception and stereognosis.

A person with PNS injury is more likely to have deficits in

touch pressure awareness and two- point discrimination.

potential symptoms of lesions affecting primary somatosensory cortex

MOST IMPACTED

- agraphesthesia

- asterognosis

- hemihypesthesia

- loss of vibration, proprioception, and fine touch

LESS RELEVANT (spinothalamic tract)

- nociception

- thermoception

- crude touch

fine touch

ability too detect when you are lightly touched

pain sensation

nociception

ability to perceive hot, cold, room temp

thermoception

crude touch

gross touch - yes or no

agraphesthesia

inability to recognize symbols, letters or numbers traced on the skin

inability to recognize symbols, letters or numbers traced on the skin

agraphesthesia

asterognosis

inability to recognize objects by touch

inability to recognize objects by touch

asterognosis

hemihypesthesia

too much sensitivity in one side of the body

too much sensation in one side of the body

hemihypesthesia

proprioception

awareness of your body in space

4 things that contribute to tactile perception:

1) pressure

2) skin stretch

3) vibration

4) temperature

*all these working together contribute to tactile perception

skin stretch gives us information on

how we are manipulating something

- squeezing

OTPF - sensation is a ...

body function

OTPF - sensation is a component of ...

client factors

OTPF - sensation influences both motor and processing aspects of

performance skills

OTPF - sensory dysfunction may affect performance in

areas of occupation

why is sensation so important?

1) required for early learning

2) affects motor performance (depends on the speed of sensation)

3) essential for effective movement (soft fist bump)

requirements for normal sensation

1) reception (somatosensory receptors) - fire

2) transmission (afferent neurons) - send messages

3) interpretation (sensory cortex) - interpret the message

*disruption in any of these challenges performance

provide information about touch, pain, pressure, temperature, and the position of muscles and limbs

somatosensory receptors

afferent neurons

Nerve cells that carry impulses towards the central nervous system

senses --> brain

efferent neuron

Neuron that conducts impulses away from the CNS to muscles and glands.

faucet example

1) touch hot water

2) thermoceptors fire

3) sensory organ will transmit to brain

4) loop - instantly take hand out

or

5) brain loop - to upper motor neurons for conscious perception

6) body executes a conscious command - take hand out

upper motor neurons

motor neurons in the central nervous system that control the lower motor neurons in the peripheral nervous system

lower motor neurons

axons leave the CNS, extend through PNS to skeletal muscles. Cell bodies in anterior horns of spinal cord and in cranial nerve nuclei of brainstem

loss of sensation impairs what kind of feedback?

tactile feedback

loss of sensation ... quality of performance

slows/diminishes

what does loss of sensation lead to:

1) impairs tactile feedback

2) slow/diminishes quality of performance

3) increases risk of injury

4) requires adequate vision for compensation

loss of sensation requires ... for compensation

adequate vision

Sensation is stimulated by receptors in the periphery of the body ... and the sensory information then travels through afferent neurons, carrying nerve impulses from the receptors to the brain ...

(PNS),

(CNS)

types of sensory dysfunction

1) paresthesia

2) hyperthesia

3) dysesthesia

4) allodynia

aesthesis

sensation

paresthesia

abnormal tactile sensation often described as creeping, burning, tingling, or numbness

hyperthesia

increased sense of feelings such as pain or touch

abnormal increase in sensitivity to stimuli

hyperthesia

dysthesia

unpleasant, abnormal sense of touch, often experience as pain

unpleasant, abnormal sense of touch, often experience as pain

dysthesia

allodynia

Pain due to a stimulus that does not normally provoke pain

Pain due to a stimulus that does not normally provoke pain

allodynia

when a person with complex regional pain syndrome (CRPS), formerly referred to as reflex sympathetic dystrophy (RSD), experiences pain with the mere movement of air wafting over the involved arm

1) paresthesia

2) hyperthesia

3) dysesthesia

4) allodynia

4) allodynia

Tapping the volar aspect of the wrist may elicit what type of sensory disfunction in the distribution of the median nerve in a person who has carpal tunnel syndrome due to the compressive nature of the disease.

1) paresthesia

2) hyperthesia

3) dysesthesia

4) allodynia

1) paresthesia - tingling, burning, pricking

selection of evaluation tools depend in whether the etiology is due to problems with:

CNS (upper neurons)

- generalized area

- proprioception, stereognosis, temperature

PNS (lower neurons)

- specific area

-pressure, discrimination, pain

generalized area sensory dysfunction

a) CNS

B) PNS

CNS

specific area sensory dysfunction

a) CNS

B) PNS

B) PNS

proprioception, stereognosis, temperature

a) CNS

B) PNS

CNS - happens in the brain

pressure, discrimination, pain

a) CNS

B) PNS

PNS - happens in specific body parts

brain's ability to reorganize neuronal connections

neuroplasticity

neuroplasticity offers implications for treatment regarding:

upper neuron deficits

lower neuron deficits

*no reorganization in the peripheral nervous system

there is no reorganization of neurons

a) PNF

B) CNS

PNS

the potential for recovery depend on:

- etiology (cause)

- severity (minimal vs massive sensory loss)

- location of lesion

- cognition

- motivation

- ability to learn new strategies

we have receptors in the periphery of the body that are stimulated by two types of sources

1) superficial (skin receptors)

2) deep sources (musculoskeletal receptors)

... nerves conduct action potential though the spinal cord to the brain

a) afferent

b) efferent

afferent nerves

types of somatosensory receptors

1) mechanoreceptors (touch, pressure, stretch)

2) chemoreceptors (cell injury/damage)

3) thermoreceptors (hot/cold)

Each of these three types of receptors has a subset called nociceptors, which sense pain when stimulated

respond to touch, pressure, stretch, and vibration and are stimulated by mechanical deformation

1) mechanoreceptors

2) chemoreceptors

3) thermoreceptors

4) nocireceptors

1) mechanoreceptors

respond to cell injury or damage and are stimulated by substances (neuropeptides) that the injured cells release.

1) mechanoreceptors

2) chemoreceptors

3) thermoreceptors

4) nocireceptors

2) chemoreceptors

respond to the stimulation of heating or cooling

1) mechanoreceptors

2) chemoreceptors

3) thermoreceptors

4) nocireceptors

3) thermoreceptors

Each type of receptor has a subset called ...

nociceptors, which sense pain when stimulated

touch a hostile liquid that causes a burning sensation

1) mechanoreceptors

2) chemoreceptors

3) thermoreceptors

4) nocireceptors

2) chemoreceptors

what are the two types of sensation?

1) primary

2) discriminatory

receives and interprets "simple" sensations

a) Primary sensation

b) discriminatory sensation

a) Primary sensation

receives and interprets more complex, integrated experiences

a) Primary sensation

b) discriminatory sensation

b) discriminatory sensation

primary sensation

receives and interprets "simple" sensations

includes pain, temperature, light touch, pressure, vibration, and proprioception

discriminatory sensation

receives and interprets more complex, integrated experiences

more parts of the brain are involved

- location of touch

- stereognosis, kinesthesia

- 2 pt discrimination

location of touch, stereognosis, kinesthesia, 2 pt

a) Primary sensation

b) discriminatory sensation

b) discriminatory sensation

awareness of touch, pain and temperature

a) Primary sensation

b) discriminatory sensation

a) Primary sensation

yes or no sensation

a) Primary sensation

b) discriminatory sensation

a) Primary sensation

what comes first:

a) Primary sensation

b) discriminatory sensation

a) Primary sensation

localization of touch

Identify the exact site where the skin has been stimulated

Kinesthesia

the system for sensing the position and movement of individual body parts

feeling of movement

neuropathy

dysfunction of the PERIPHERAL nervous system

dysfunction of the peripheral nervous system

neuropathy

neuropathy sequence of loss

1) discriminative touch and proprioception (silk vs yarn)

2) cold

3) heat

4) pain

causes more damage

a) heat

b) cold

heat

neuropathy sequence of return

1) pain

2) heat

3) cold

4) discriminative touch and proprioception

it is vital that pain returns first because of

safety

nerve sheath loss

slower transmission

loose some of the impulses along the way (weaker message)

nerve disconnection

nothing gets transmitted

info does not get to the brain and vice versa

nerve degeneration

whole system breaks apart

conduction speed

bad receiving

weak signal

superficial sensation

touch

cutaneous sensation

--- part of our body have higher density receptors and smaller receptor fields

a) proximal

b) distal

distal

- enhanced fingertip sensation

test that enables us to tell the difference between a penny and a dime

2 pt discrimination test

superficial sensation includes:

- touch (am I being touched?)

- temperature (hot vs cold)

- pain (pain vs no pain)

Compared with the more proximal body parts, the distal parts have

a higher density of receptors and smaller receptive fields

most discriminative sensation is in what body part?

fingertips

importance of temperature sensation for the clinic

- Important to test temperature sensation prior to applying thermal modalities

- Important for an individual to determine safe temperature for washing hands/bathing

- Safety during meal preparation

- Compensatory strategies may be priority

Important to test temperature sensation prior to

applying thermal modalities