Lecture 2: Cutaneous Sensation - Central pathways

Question 1

Is sensory information transmitted to the same or opposite side of the brain?

Answer 1

Opposite side.

Question 2

Does the gracile or cuneate tract contain afferents from the lower part of the body?

Answer 2

Gracile tract - lower

Cuneate tract - upper

Question 3

Where are the gracile nucleus and the cuneate nucleus located?

Answer 3

In the medulla.

Question 4

Where do the second order neurons of the dorsal column pathway synapse onto third order neurons?

Answer 4

The thalamus.

Question 5

Where do the axons of the dorsal column pathway cross to the other side of the body?

Answer 5

In the medulla.

Question 6

What two classes of sensory information are conveyed through the dorsal column pathway?

Answer 6

Touch (low threshold mechanoreceptors)
And
Joint position sense (proprioceptors in muscle and joints)

Question 7

Where do the axons of the spinothalamic tract cross to the other side of the body?

Answer 7

In the spinal cord.

Question 8

Which pathways conveys information from nociceptors, thermoreceptors and pruritoceptors (itch receptors)?

Answer 8

The spinothalamic tract.

Question 9

Where do both the dorsal column pathway and the spinothalamic tract pass through in the pons?

Answer 9

The medial lemniscus.

Question 10

Which pathway projects only to the Ventral Posterior (VP) nucleus of the thalamus?

Answer 10

Dorsal column pathway.

Question 11

Where does the spinothalamic tract project to in the thalamus?

Answer 11

The VP (ventral posterior nucleus) and the intralaminar nuclei. Therefore the spinothalamic tract also has access to cortical areas other than S1.

Question 12

Which pathway is phylogenetically older?

Answer 12

Spinothalamic tract.

Question 13

Which pathway plays a part in recognition of shape and identifying direction of movement of a stimulus?

Answer 13

Dorsal column pathway.

Question 14

Which Brodmann areas make up the S1 cortex?

Answer 14

3a, 3b, 1 and 2.

Question 15

Where is the posterior parietal cortex located?

Answer 15

Behind S1. Brodmann areas 5 and 7.

Question 16

Which area of the S1 cortex has a proprioceptive function?

Answer 16

3a

Question 17

Which area of the S1 cortex is involved in cutaneous sensation?

Answer 17

3b.

Question 18

Where do areas 1 and 2 of S1 receive input from? And what are the sections related to?

Answer 18

Areas 1 and 2 receive input from area 3b. Area 1 is involved in the sensation of texture and area 2 is involved in the sensation of size and shape.

Question 19

What are two features of the columns in the S1 cortex?

Answer 19

Each column contains neurons that have similar responses.

And there are separate columns with rapidly and slowly adapting responses.

Question 20

When the S2 cortex is activated, is it unilateral or bilateral?

Answer 20

Bilateral as the two sides are strongly interconnected.

Question 21

Where does the S2 cortex receive input from in the brain?

Answer 21

The thalamus and S1.

Question 22

Which sensations activate the S2 cortex?

Answer 22

Tactile, painful and visceral sensation.

Question 23

What does the posterior parietal cortex do?

Answer 23

Integrates somatosensory, auditory and visual information.