The Somasensory System

Question 0

How many types of systems are within the somatosensory system and what are they?

Answer 0

3
The exteroceptive system
The proprioceptive system
The interoceptive system

Question 1

What is the role of the somatosensory system?

Answer 1

To perceive bodily sensations

Question 2

What is the exteroceptive system responsible for?

Answer 2

Touch and external stimuli sensation of the skin

Question 3

What is the interoceptive system responsible for?

Answer 3

Sensations for internal conditions such as temperature, blood pressure

Question 4

What is the proprioceptive system responsible for?

Answer 4

The sensation of the orientation of the limbs

Question 5

Name the receptors found in the dermis and epidermis. What somatosensory system would these belong to?

Answer 5

The cutaneous receptors. These would belong to the exteroceptive system

Question 6

Explain the cutaneous receptor, free nerve ending cells.

Answer 6

Free nerve ending cells have no structure and are sensitive to pain and temperature

Question 7

Explain the cutaneous receptor of pacinlan corpuscles.

Answer 7

Pacinlan corpuscles respond RAPIDLY to pressure and adapt quickly

Question 8

Explain the cutaneous receptor of ruffini endings.

Answer 8

Ruffini endings respond and adapt GRADUALLY to pressure.

Question 9

If I was to bump into an object what pressure cutaneous receptor would code for this?

Answer 9

Pacinlan corpuscles

Question 10

If I was to sit on a chair for a long period of time what cutaneous pressure receptor would code for this?

Answer 10

Ruffini’s endings

Question 11

What is a dermatome? What makes this system a bit more robust?

Answer 11

A dermatome is where the afferent, dorsal nerves on the spinal cord code for a particular skin region. It is made more robust as there is considerable overlap between each dermatome.

Question 12

How many pathways from body to cortex are there in the somatosensory system? Name them.

Answer 12

2
The dorsal column medial-leminiscus
The anterolateral system

Question 13

What pathway carries information about touch and proprioception to the cortex?

Answer 13

The dorsal column medial-lemniscous

Question 14

What pathways carries information about pain and temperature to the cortex?

Answer 14

The anterolateral system

Question 15

Which pathway is considered to be more important? Why? and how is this pathway harder to break?

Answer 15

The anterolateral system pathway. As this system codes for pain and pain is vital for survival. It is considered “indestructible” as it contains 3 tracks.

Question 16

If both an excitatory and inhibitory region are stimulated at the same time, what type of firing occurs?

Answer 16

Baseline firing.

Question 17

Why is pain important ?

Answer 17

As it is adaptive. It encourages learning and treatment about particular things

Question 18

What cortical region is responsible for pain ?

Answer 18

There is no specific cortical region for pain. Whole hemispheres of the brain can be removed and pain will still be felt

Question 19

However, what area is associated with the emotional responses of pain? What system does this belong to?

Answer 19

The anterior gingulate gyrus of the limbic system

Question 20

What is the function of the periaqueductal gray (PAG)?

Answer 20

The PAG is the body’s built in pain reducer

Question 21

How does the PAG reduce pain sensation?

Answer 21

electric stimulation
Receptors for opiates
Endorphins

Question 22

Fill in the blanks.

Dorsal columns, ……. Medial lemnisicus, …….. , primary somatosensory cortex

Answer 22

Dorsal columns, dorsal column nuclei, medial lemnisicus, ventral posterior nucleus, primary somatosensory cortex

Question 23

Name all 5 stages of the somatosensory receptor to cortex pathway.

Answer 23

Dorsal column, dorsal column nuclei, medial lemnisicus, ventral posterior nuclei, somatosensory pathway

Question 24

What region on the thalamus does the somatosensory pathway project onto?

Answer 24

Ventral posterior nuclei

Question 25

What region of the somatosensory pathway is where the medulla begins?

Answer 25

Dorsal column nuclei

Question 26

What connects the medulla (dorsal column nuclei) to the thalamus (ventral posterior nucleus)?

Answer 26

Medial lemnisicus

Question 27

At what stage does the triGerminal nucleus join onto the pathway?

Answer 27

During the medial lemnisicus

Question 28

Where is the primary somatosensory cortex located?

Answer 28

Posteriorly to the central fissure in the postcentral gyrus.

Question 29

Where is the secondary somatosensory cortex located?

Answer 29

Inferiorly to the primary somatosensory cortex, hidden in the lateral fissure

Question 30

What is a pathway called when it runs against the typical receptor to cortex pathway? When is it used?

Answer 30

Centrifugal pathway. Used for pain.

Question 31

Why use a centrifugal pathway to block pain?

Answer 31

As it reduces pain in times of intense emotional stress in order to increase chances of survival.

Question 32

Fill in the blanks for the centrifugal pathway of pain.

1. Periaqueductal gray
3. Dorsolateral spinal cord

Answer 32

2. Raphe nuclei

Question 33

Fill in the blanks for the centrifugal pathway of pain.
1.
2. Raphe nuclei
3.

Answer 33

1. Periaqueductal gray

3. Dorsolateral spinal cord

Question 34

How is the somatosensory system organised?

Answer 34

Somatopically

Question 35

Explain the somatosensory homunculus. What is distorted ?

Answer 35

Somatosensory homunculus is the map of all body part sensations controlled for in the primary somatosensory cortex. Hands, face and lips are greatly represented as they contain the highest number of sensation cells .