Touch.

Question 1

Is touch essential for proprioception?

Answer 1

Yes.

Question 2

What are most of the receptors that contribute to touch?

Answer 2

Free nerve endings within the skin.

Question 3

How do the receptors that respond to touch vary?

Answer 3

They have different sensitivities, some are very sensitive, others take massive pressure before any stimulus is generated.

Question 4

What and pacinian corpuscles?

Answer 4

Sensors found in the subcutis.

Question 5

What is sensed by pacinian corpuscles?

Answer 5

Vibrations.

Question 6

What animals are pacinian corpuscles often found in?

Answer 6

On the wingtips of birds or in animals that hunt.

Question 7

What spinal tract is used for the sense of touch?

Answer 7

The dorsal column.

Question 8

Will the sense of touch be ipsilateral or contralateral as it runs up the spinal cord?

Answer 8

It stays ipsilateral until it reaches the medulla, where it crosses over and travels to the cortex.

Question 9

What are dorsal cutaneous branches of spinal nerves?

Answer 9

Small branches that project off each spinal nerve.

Question 10

What is the function of the dorsal cutaneous branches?

Answer 10

They innervate a small section of skin which is known as a dermatome.

Question 11

What kind of nerves innervate the forelimb?

Answer 11

Plexus nerves.

Question 12

Are spinal nerves found in the forelimb?

Answer 12

Spinal nerves travel to the brachial plexus and then plexus nerves continue to innervate the forelimb.

Question 13

What name is given to the area of skin that is innervated by a plexus nerve?

Answer 13

An autonomous zone.

Question 14

How do touch stimuli travel from the free nerve endings to the spinal cord?

Answer 14

Down a spinal/plexus nerve (first order neuron) to the dorsal grey horn of the spinal cord.

Question 15

How does a touch stimulus travel up a 2nd order neuron?

Answer 15

It travels up the spinal cord to the medulla.

Question 16

How does a touch stimulus travel up a 3rd order neuron?

Answer 16

It crosses over in the medulla and then travels to the cortex to be processed.

Question 17

Can we use dermatomes to test spinal nerves?

Answer 17

Yes.

E.g. If we test spinal nerve T8 we find the correct dermatome and touch it or prick it to see if we get a normal response.

Question 18

How can we tell if there is damage to a spinal nerve or plexus nerve from a dermatome?

Answer 18

There will be loss of sensation in that dermatome or autonomous zone.

Question 19

How can we tell if there is damage to the spinal cord?

Answer 19

There will be no sensation anywhere below the location of the damage.

Question 20

When does the cutaneous trunci reflex occur?

Answer 20

When we stimulate the skin in the thoracolumbar region of an animals back.

Question 21

What happens in the cutaneous trunci reflex after the animals skin has been stimulated?

Answer 21

There is contraction of the cutaneous trunci muscle.

Question 22

What nerve innervates the cutaneous trunci muscle?

Answer 22

The lateral thoracic nerve.

Question 23

Where does the lateral thoracic nerve originate from?

Answer 23

Around the level of the shoulder.

Question 24

The lateral thoracic nerve receives nerve fibres from what vertebrae?

Answer 24

The vertebrae from C8 to T1.

Question 25

What kind of nerve is the lateral thoracic nerve?

Answer 25

A motor nerve with no sensory elements.

Question 26

What happens in the cutaneous trunci reflex if we prick the animal at the level of L3?

Answer 26

The cutaneous trunci muscle should twitch if the reflex is working.

Question 27

When will the cutaneous trunci reflex not be working?

Answer 27

If there is damage to the spinal cord above the point where you prick the animals back.

Question 28

In what direction will we test the cutaneous trunci reflex?

Answer 28

From caudal to cranial.

Question 29

The cutaenous trunci reflex can be tested between what areas of the spinal cord?

Answer 29

C8/T1 to L4/L5.