Week 3

Question 1

How is the spinal cord made up

Answer 1

The middle of the cord (H shape) is made up of neurones and other cells (grey matter) whereas the outside of the cord is made up of the fibres (white matter) that carry information up and down the cord

Question 2

What is the spinal cord

Answer 2

An extension of the brainstem, from the medulla

Question 3

What do the dorsal and ventral horn do and where are they located on the spine

Answer 3

Dorsal horn (the back of the H shape) is where sensory information is localised. Information about the body such as fine touch, proprioception and vibration are stored.
Ventral horn (at the front) is where the motor neurones are located - makes direct contact onto the muscles. Stimulation of these neurones causes movement.

Question 4

2 main descending systems

Answer 4

Lateral descending system
Medial descending system
Take info out of the brain and send to motor system to produce movement

Question 5

Lateral descending system

Answer 5

Involves the corticospinal and rubrospinal tracts.
Fibres of the lateral system are in the dorso-lateral part of the spinal cord. They connect to motor neurones in the lateral part of the ventral horn. This system influences lateral musculature (movement in the arms and legs)

Question 6

Medial descending system

Answer 6

Involved in the control of balance and posture
Involves the vestibular and reticulospinal tracts.
Fibres of the medial system are in the ventro-medial part of spinal cord. They connect to motor neurones in the medial part of the ventral horn.

Question 7

2 main ascending systems

Answer 7

Medial lemniscus/dorsal column pathway
Spinothalamic tract

Question 8

Dorsal Root Ganglion (DRG)

Answer 8

The cell bodies of incoming sensory neurones lie outside the spine in a series of ganglion, called the DRG

Question 9

Dermatomes

Answer 9

An area of the skin supplied by nerves from a single spine root

Question 9

2 point discrmination

Answer 9

The ability to discern that 2 nearby objects are touching the skin.
Some areas of the body have more sensory neurones than others.

Question 10

All the motor neurones that innervate a single muscle are called a

Answer 10

Motor pool

Question 11

Spinal enlargements

Answer 11

The arms and legs have many highly innervated muscles and have a high density of sensory receptors. Because of this, the portions of the spinal cord that provide the spinal nerves to the arms and legs are enlarged

Question 12

Motor nuerones use a _________ to signal the amount of force to be exerted by a muscle.

Answer 12

Rate code

Question 13

Relationship between rate of action potentials and force generated by motor units

Answer 13

An increase in the rate of action potentials fired by the motor neurone causes an increase in the amount of force that the motor unit generates.

Question 14

Single action potentials will produce

Answer 14

Single twitches

Question 15

Tectanic contraction

Answer 15

A maximal contraction. Frequency is so fast that the muscle cannot relax between action potentials

Question 16

Stretch reflex

Answer 16

Signals sent to the muscle to oppose the stretch being felt by a muscle

Question 17

2 important brainstem nuclei groups that control movement

Answer 17

Reticular formation
Vestibular nuclei

Question 18

Vestibular system

Answer 18

The sensory system that provides the sense of balance and spatial orientation

Question 19

Basal ganglia

Answer 19

Function is movement regulation (selection of appropriate behaviours)
There are 2 pathways through the BG, both starting and finishing in the cortex.
-direct (pro movement) and indirect (anti movement)

Question 20

Damage to the BG and the cerebellum

Answer 20

Damage to the BG produces states where there is too much or too little movement
Damage to the cerebellum produces states where movements can still be made, but they are uncoordinated.

Question 21

Primary motor cortex

Answer 21

Neurone in the primary motor cortex have a simple relationship to movement. They fire around 5 to 100 ms before movement onset and can code for force, direction and speed.

Question 22

Pre motor cortex

Answer 22

Neurones code for more complex parameters of movement

Question 23

Supplementary motor cortex

Answer 23

Neurones code other complex aspects of movement that are different to those in the pre motor cortex

Question 24

Primary sensory cortex

Answer 24

Touch and proprioception

Question 25

Posterior parietal cortex

Answer 25

Integration of sensory, visual information to execute complex movements