Week 3: Peripheral and Central Somatosensory System

Question 1

Closed Loop

Answer 1

Closed loop: feedback at the end [Reaching] continuous feedback (sensory feedback while you’re doing the movement) Damage from dorsal root is why you would have damage
- Most ADL movements involve sensory feedback, when reaching for cup you’re faster in the beginning and begin to slow down to grab object and not knock it over

Question 2

Open Loop

Answer 2

Open loop: constant feedback
- Throwing: Doing it so fast there’s no time for sensory feedback until it’s over

Question 3

Three-neuron somatosensory pathways (first order, second order, third order)

Answer 3

First order: Sensory receptor to dorsal root ganglion of the spinal cord (brings information to the brain)
Second order: Spinal cord or brainstem to the thalamus
Third order neuron: Thalamus to cerebral cortex (sorts to appropriate part)

Question 4

Cutaneous sensory information

Answer 4

Touch (superficial pressure and vibration) nociception, and temperature – signal to brain that something is injured

Question 5

Musculoskeletal sensory information

Answer 5

Proprioception (static and kinesthetic)

Question 6

Mechanoreceptors

Answer 6

Touch, pressure, stretch, vibration

Question 7

Chemoreceptors

Answer 7

Respond to chemicals released by cells following damage or infection

Question 8

Thermoreceptors

Answer 8

Hot/Cold

Question 9

Tonic Receptors

Answer 9

Constant

Question 10

Phasic Receptors

Answer 10

Temporary

Question 11

conduction velocity of sensory axon

Answer 11

Most large diameter afferents (Ia, Ib, II, AB) are triggered only by mechanical stimuli – Small to large

Question 12

Receptive Fields

Answer 12

-The are of skin innervated by a single afferent neuron
- Receptive fields are smaller in the distal extremities

Question 13

Muscle Spindles

Answer 13

Convery information on the length and rate of change in length of the muscle.

Question 14

Golgi Tendon Organs

Answer 14

a proprioceptor, sense organ that receives information from the tendon, that senses TENSION.

Question 15

Joint Receptors

Answer 15

Respond to mechanical deformation of the capsule and ligaments

Question 16

Somatotropin anatomical cortical representation

Answer 16

The face/different parts of the body across the brain

Question 17

Neuropathy

Answer 17

happens when the nerves that are located outside of the brain and spinal cord (peripheral nerves) are damaged. This condition often causes weakness, numbness and pain, usually in the hands and feet.

Question 18

Proprioception

Answer 18

The ability to identify trunk and limb position in space when vision is occluded.
1. Occlude to pt. vision
2. Move the pt. UE 3 times between shoulder flexion and extension (**The last position should place the extremity into shoulder flexion)
3. Ask the pt. “Is your arm up or down? Can you replicate the position with your other arm”
(Shoulder, Elbow, Wrist, Thumb – bent or straight, Pinky)
Upper extremities: Getting dressed in the dark, or a dark closet knowing where to place your arms. Grabbing something from a shelf if you cant see it.

Question 19

2-point discrimination

Answer 19

The ability to determine whether one has been touched by 1 or 2 points. This sensory function allows an individual to perform precision grip movements during ADLs and IADLs (it prevents one from dropping objects)
1. Occlude the pt. vision
2. Apply an esthestiometer to the pt. uninvolved thumb. Ask the pt. whether 1 or 2 points have touched him or her. Gradually move the distance closer (THE 3 SMALLEST).
3. Apply an esthestiometer to the pt. uninvolved index finger. Ask the pt. whether 1 or 2 points have touched him or her.
4. Repeat with pinky

Question 20

Sterognosis

Answer 20

Sterognosis (Pg. 76)
The ability to recognize shapes, objects, and textures by touch, with vision occluded. Allows individuals to identify familiar objects without the use of vision.

Familiar objects

Question 21

Ahylognosia

Answer 21

Textures

Question 22

Amorphagnosia

Answer 22

Shapes

Question 23

Graphestesia

Answer 23

Drawing on hand

Question 24

A client reaches into her purse to find her keys. She tells her OT she has a hard time finding things in her purse and everything feels the same what is most likely impaired.

Answer 24

Sterognosis

Question 25

The OTS asks the client to close their eyes and then moves the client’s thumb 3 times between thumb flexion and extension and then places the thumb in extension.

Answer 25

Proprioception

Question 26

Below are list of assessments and the materials used to test them.

Answer 26

Ahylognosia - Sandpaper
Amorphagnosia - A small cube, sphere, and cone
2 point discrimination - Esthesiometer
Sterognosis - A bag of small every day objects

Question 27

A pediatric OTR is working with a 6 year old. The childs mother complains that the child is very clumsy and is always tripping or bumping into walls.

Answer 27

Proprioception - Where there body is in space

Question 28

A 2-point discrimination impairment would most likely reveal itself in which of the following activties

Answer 28

Typing without looking at your hands

Question 29

Damage to the dorsal root ganglion would more so impair ____ movements such as reaching as opposed to throwing.

Answer 29

Closed loop

Question 30

Where is the decussation point of the dorsal column/medial lemniscus pathway, to the contralateral side of the body?

Answer 30

Medulla of the brainstem

Question 31

What information do muscle spindles convey

Answer 31

Length and rate of change in length of a muscle

Question 32

Increased axon diameter ___ nerve conduction velocity

Answer 32

Increases

Question 33

How many neurons are along a single somatosensory pathway

Answer 33

3