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RAMLA A. SANDAG – JAILANI, RAMLA A. SANDAG – JAILANI, M.D. M.D. Physiology department Physiology department kkuh kkuh
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RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

Jan 03, 2016

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Page 1: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

RAMLA A. SANDAG – JAILANI, M.D.RAMLA A. SANDAG – JAILANI, M.D.

Physiology departmentPhysiology department

kkuhkkuh

Page 2: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

Somatosensory system (Somatovisceral Sensory System)

- transmits sensations from receptor organs

in the skin, muscles, joints and viscera

to the brain.

Page 3: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

*Two )2( main pathways:

1 .Posterior )Dorsal( Column Lemniscal tract

- fine touch, two-point discrimination , vibration and position sensations,

fine pressure

2 .Spinothalamic )Anterolateral( tract - pain and thermal sensations, crude

touch, crude pressure, tickle and itch

Page 4: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

OBJECTIVES:

To be able to reasonably acquire the skill of testing the following general sensation:

1 .tactile sensations – light touch, pressure, tactile

localization and discrimination2 .joint position sense

3 .recognition of size, shape, weight forms and

textures of objects 4 .vibration sense5 .pain sensations

6 .temperature sense

Page 5: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

REQUIREMENTS:

Cotton wools Thin bristles

Calipers, pins or disposable toothpicks

Test tubes with warm and cold water

Flat base tuning forks Different weights

Page 6: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

TACTILE LOCALIZATION:

1 .Ask the subject to close her eyes.

2 .Touch different parts of the body with cotton wool.3 .Ask her to acknowledge

whether she feels the touch and ask her to locate the

exact area touched.4 .Note whether there is

abnormality like hypoaesthesia or hyperaesthesia.

* Hypoaesthesia – touch sensation is reduced. * Hyperaesthesia – sensations produced is

either painful, irritating, or tingling.

Page 7: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

Spinothalamic tract interruption

- increase touch threshold - decrease in no. of touch

spots in the skin

- slight touch deficit - normal touch localization

Page 8: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

Dorsal columns destroyed

- vibration and proprioception sense are lost

- increase touch threshold - no. of touch-sensitive areas in the

skin - impaired localization of touch

sensation

Page 9: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

TWO-POINT DISCRIMINATION:

1 .Ask the subject to close her eyes.

2 .With the calipers wide apart, touch two areas of the back of the hand.3 .Ask the subject to say

whether she feels two points of touch or a

single point.

Page 10: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

4 .Now decrease the distance between two limbs of the

caliper and measure in millimeter)mm( the minimum

distance that can be recognized as two distinct

points.

*Two-point threshold – is the minimum distance at which two

points of contact can be felt.

– is impaired in: dorsal column and parietal

cortical )somatosensory cortex( lesions5 .Determine two-point threshold in the

following areas – palm of the hand, fingertip, leg and back of

the neck.

Page 11: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

RECOGNITION OF SIZE, SHAPE AND FORMS:

1 .Ask the subject to close her eyes.

2 .Place any common object like coins, keys, pen, etc .

in her palm and ask her to identify the object without

looking towards it.

Page 12: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

* Stereognosis – ability to recognize objects.

* Astereognosis – loss of recognition of objects.

– early sign of damage to cerebral

cortex. – if without defect in touch and

pressure sensation ( Parietal lobe lesion posterior

to postcentral gyrus)

Page 13: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

RECOGNITION OF WEIGHT DISCRIMINATION:

1 .Ask the subject to close her eyes and place her

hand on the table.2 .Place different weighs

in his hands.3 .Ask her to indicate if

she could identify the variations in the weights

placed on her hand.

Page 14: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

Weight discrimination – the ability to assess the

weight of an object.

* An increase in intensity of stimuli is transmitted

to the brain in the form of : a. an increase in the number of

afferent fibers stimulated

b. increased frequency of action potentials in

these fibers

… These two features are perceived as an

indication of the strength of the stimulus.

Page 15: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

VIBRATION SENSE:

1 .Ask the subject to close her eyes.

2 .Strike the tuning fork ( 128 – 250 cps )and place

it successively over identical body areas on each side of

the body.3 .Ask the subject to acknowledge

whether she feels the vibration and whether it is of the same

intensity on the two sides.

Page 16: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

4 .Proceed from the upper part of the body downwards – the clavicle, tip of the shoulder, elbow, wrist ,

dorsum of the hand, anterior chest wall, anterior

superior iliac spine, patella, tibial tuberosity ,

lateral and medial malleoli and the base of the

big toe.5 .Test if the subject can accurately identify

when the vibration stops.

Page 17: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

Vibration – a pattern of rhythmic pressure stimuli

… receptors involved: touch receptors especially

Pacinian corpuscles … pathway: dorsal column … degeneration occurs in:

- poorly controlled diabetes - pernicious anemia

- some vitamin deficiencies

Page 18: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

JOINT POSITION SENSE:

1 .Ask the subject to close her eyes.

2 .Hold her finger or toe and make it up and down and ask her to recognize: a. movement of the joint

by saying NOW b. direction of the fingers

whether up or down.

Page 19: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

PAIN SENSATION:

* SUPERFICIAL … With the prick of

a pin, elicit the sensation of pain

on a willing partner.

Page 20: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

*PRESSURE

… Put pressure on deep structures such as

muscles, tendoachilles or bones, superior

orbital margin, etc and ask her whether she

feels pain.

Page 21: RAMLA A. SANDAG – JAILANI, M.D. Physiology department kkuh.

TEMPERATURE SENSE:

1 .With two test-tubes containing warm and

cold water, touch at different sites of the body of your subject.

2 .Ask her to identify the temperature differences.