Somatosensory system

Question 1

What do low threshold mechanoreceptors mediate?

Answer 1

Touch, vibration and pressure

Question 2

What do low threshold thermoreceptors mediate?

Answer 2

Cold, cool, indifferent, warm and hot

Question 3

Over what temperature is classed at “extreme heat”

Answer 3

45 degrees

Question 4

What term describes cutaneous senses from the surface of the body?

Answer 4

Exteroceptive sensations

Question 5

What term describes sensation concerning posture and movement? (Sensors located in muscle tendons and joints)

Answer 5

Propriceptive sensations

Question 6

In sensory neurones; does a stimulus elicit a depolarizing or hyperpolarizing response?

Answer 6

Depolarizing

Question 7

Which sensory neurones have the thickest layer of myelination

Answer 7

Proprioceptors of skeletal muscle; Aα receptors

Question 8

Which sensory neurones have the thinnest layer of myelin?

Answer 8

Temperature, pain and itch “C” receptors.

Question 9

What is the receptive field of a sensory neurone?

Answer 9

The region that, when stimulated with an adequate stimulus, causes a response in that neurone

Question 10

Where are meissners corpuscles most abundant?

Answer 10

Skin where two point discrimination is highest

Question 11

Where do you not get any meissners corpscules?

Answer 11

Hairy skin

Question 12

What pathway carries the sensations of discriminatory touch, pressure vibration and conscious propriception from the sensory neurones to the brain?

Answer 12

Dorsal column medial lemniscal pathways

Question 13

Where do the fibres of the dorsal column medial lemniscal pathway cross?

Answer 13

All cross together at the medulla

Question 14

What pathway carries the sensations of pain, temperature, crude touch, itch and tickle from the sensory neurones to the brain?

Answer 14

Spinothalamic tract

Question 15

Where do the fibres of the spinothalamic tract cross?

Answer 15

At all levels of the cord close to the point of entry.

Question 16

What two tracts make up the dorsal column?

Answer 16

Gracile tract

Cuneate tract

Question 17

What tract of the dorsal column carries sensory inputs from T6 and below?

Answer 17

Gracile tract

Question 18

Of the gracile and cuneate tracts which is more medial and which more lateral?

Answer 18

Gracile tract is more medial and cuneate tract is more lateral

Question 19

What tract of the dorsal column carries sensory inputs from above T6?

Answer 19

Cuneate tract

Question 20

Where do the neurones travelling in the gracile tract synapse?

Answer 20

Dorsal column gracile nucleus

Question 21

Where do the neurones travelling in the cuneate tract synapse?

Answer 21

Dorsal column cuneate nucleus

Question 22

In the dorsal column medial lemniscal system; where do the second order neurones cross, and where do the ascend after this?

Answer 22

Axons from second order neurones cross in the great sensory decussation and ascend in the medial lemniscus.

Question 23

After the second order neurones of the dorsal column medial lemniscus pathways have ascended up the medial lemniscus pathway where on the thalamus do they synapse?

Answer 23

The ventral posteriolateral nucleus of the thalamus

Question 24

Where do the third order neurones in the dorsal column medial lemniscus pathway project to? What do they have to go via to get here?

Answer 24

Primary somatosensory cortex

Posterior internal capsule

Question 25

A patient loses the ability to recognise an object just by feeling it. What pathway is likely to be damaged?

Answer 25

dorsal column medial lemniscus pathway

Question 26

A patient can’t feel the vibration of a tuning fork. What pathway is likely to be damaged?

Answer 26

dorsal column medial lemniscus pathway

Question 27

A patient loses the ability to recognise whether his finger is being moved up or down. What pathway is likely to be damaged?

Answer 27

dorsal column medial lemniscus pathway

Question 28

What thalamic nucleus do trigeminal nerve neurones project onto?

Answer 28

Ventroposteromedial nucleus of the thalamus

Question 29

through which type of neurones do third order trigeminal nerve neurones relay information to the cortex?

Answer 29

Thalamocortical neurones