Exam 3 Somatosensory system

Question 1

What is the function of the receptor?

Answer 1

To translate external energy forms into action potentials

Question 2

Receptor can be likened to what?

Answer 2

Transducers

Question 3

T/F Receptors can be specialized endings of afferent neurons or can be cells that are separate from the afferent neurons

Answer 3

True

Question 4

What kind of potential is a receptor potential?

Answer 4

Graded potential

Question 5

Which receptors show adaptation to a stimulus?

Answer 5

All receptors show some degree of adaptation

Question 6

Free nerve endings have what type of innervation?

Answer 6

Lightly myelinated Group III (A-delta) axons OR Group IV (C) unmyelinated axons

Question 7

What are hair receptors innervated by?

Answer 7

Lightly myelinated Group III (A-delta) axons

Question 8

Merkel’s receptors, Meisner’s, Pacinian and Ruffini corpuscles have what type of nerve fibers?

Answer 8

A-beta myelinated axons

Question 9

What is lateral inhibition?

Answer 9

A way to localize a stimulus, by inhibiting input from area around the stimulus

Question 10

What size of receptive fields have the greatest acuity or discrimination ability?

Answer 10

Smaller ones

Question 11

What are the two submodalities of limb proprioception?

Answer 11

Limb position sense (stationary) and kinesthesia (sense of limb movement)

Question 12

What are the four type of receptors the stationary and mobile positions of the limb?

Answer 12

Joint receptors, muscle spindles, golgi tendon organs, and cutaneous mechanoreceptors.

Question 13

What are the four types of joint receptors?

Answer 13

Free nerve endings, Ruffini’s endings, Paciniform corpuscles, and Ligament receptors

Question 14

What is the receptor for the stretch reflex?

Answer 14

The muscle spindle

Question 15

Where are most golgi tendon organs found?

Answer 15

In the origin and insertion aponeurosis

Question 16

What pathway carries discriminative tactile sensations from the body?

Answer 16

Dorsal Column-Medial Lemniscal Pathway (DCML)

Question 17

Axons in the DCML from the lower extremities are carried in what fasciculus? From upper extremities?

Answer 17

Gracilis. Cuneatus

Question 18

Where do DC axons terminate?

Answer 18

In the medulla as the synapse unto the nucleus gracilis and nucleus cuneatus

Question 19

What do the neurons in the gracilis and cuneatus nuclei ascend thru the brainstem as?

Answer 19

Medial Lemniscus

Question 20

What are the second order neurons of the DCML pathway?

Answer 20

The medial lemniscus neurons

Question 21

Where does the ML ascend to from the medulla?

Answer 21

Thalamus

Question 22

Where do the ML neurons synapse on the thalamus?

Answer 22

VPL nucleus

Question 23

What are the third order neurons of the DCML

Answer 23

Thalamic neurons that ascend thru the corona radiata to the primary somatosensory cortex

Question 24

What pathway carries discriminative tactile sensations from the face?

Answer 24

Trigeminal Lemniscal pathway

Question 25

Where are the second order neurons of the trigeminal lemniscus pathway?

Answer 25

In the trigeminal main sensory nucleus

Question 26

Where do axons from somas in the trigeminal main sensory nucleus decussate?

Answer 26

In the pons

Question 27

Where do the trigeminal lemniscus axons synapse on the thalamus?

Answer 27

VPM

Question 28

From which part of the thalamus do the thalamocortical projections arise?

Answer 28

VPL

Question 29

Which pathway carries pain and thermal sense from free nerve endings and heat and cold receptors?

Answer 29

Lateral spinothalamic tract

Question 30

What kind of nerve fibers does the lateral spinothalamic tract carry?

Answer 30

A-delta and C afferents

Question 31

Where do the lateral spinothalamic tract axons synapse?

Answer 31

In the substantia gelotinosa of Rexed’s Lamina II

Question 32

How many segments does the lateral spinothalamic tract ascend up the spinal cord before crossing?

Answer 32

1-2 segments

Question 33

Where does the lateral spinothalamic tract cross?

Answer 33

At the anterior white commissure

Question 34

Which neurons are considered 3rd order in the lateral spinothalamic tract?

Answer 34

Thalamic neurons

Question 35

The thalamocortical projection is part of what brain regioln?

Answer 35

Corona radiata

Question 36

Which ascending pathway carries pain and thermal sense from free nerve endings and head and cold receptors in the skin of the face?

Answer 36

Trigeminothalamic tract.

Question 37

The trigeminothalamic tract has what kinds of nerve fibers?

Answer 37

A-delta and C afferents