Motor cortex and motor pathways

Question 1

What is the primary motor area responsible for

Answer 1

Initiation of voluntary motor activity

Question 2

What is the premotor area responsible for

Answer 2

Storing programs for learned motor activities

Question 3

Where are the Frontal eye fields located

Answer 3

In the prefrontal cortex, considered part of the oculomotor system

Question 4

What is the role of frontal eye fields

Answer 4

Stimulates saccadic (quick, simultaneous) eye movements–> need this to allow both eyes to move separately/together

Question 5

Role of vestibulospinal tract

Answer 5

Send info from inner ear to monitor position of head

vestibular nuclei responds by altering muscle tone, neck contraction and limbs for posture and balance

Question 6

Role of tectospinal tract

Answer 6

Send info to the head, neck and upper limbs in response to bright and sudden movements and loud noises

Question 7

What does tectum area consist of

Answer 7

Superior colliculi–> recieves visual info

Inferior colliculi–> recieves auditory info

Question 8

Role of Reticulospinal Tract

Answer 8

Sends info to cause eye movements and activate respiratory muscles

Question 9

Role of Rubrospinal Tract

Answer 9

Sends info to flexor and extensor muscles

Question 10

How many synapses does the corticospinal tract have

Answer 10

It is monosynatic (only upper and lower motor neuron)

Question 11

Role of corticospinal tract

Answer 11

Primarily voluntary motor function

Axons arising from the parietal lobe modulate transmission of sensory signals to brain by synapsing with DCS

Question 12

How many fibres of corticospinal tract decussate

Answer 12

85-90% fibres

Question 13

Where do these fibres of corticospinal tract cross

Answer 13

At pyramidal decussation in medulla oblongata

Question 14

What tract do the crossed fibres of corticospinal tract form?

Answer 14

Lateral Corticospinal tract

Question 15

What tract do the uncrossed fibres of corticospinal tract form?

Answer 15

Ventral corticospinal tract

Question 16

What is the lateral corticospinal tract responsible for

Answer 16

Responsible for skilled volitional movement (primarily of limbs)
Conscious control over skeletal muscles
Modulates transmission of sensory input via ascending sensory pathways

Question 17

Where does the ventral corticospinal tract cross?

Answer 17

Decussates at the level of SC in ventral white comissure

Question 18

What is the vnetral conrticospinal tract responsible for?

Answer 18

Primarily concerned with the conscious control of axial (trunk) muscle
Conscious control over skeletal muscles

Question 19

Explain the path of the corticospinal tract from the motor cortex to where it decussates at the pyramids

Answer 19

Axons from cerebral cortex
Transverse subcortical white matter and posterior lib of internal capsule
Brainstem:
-Basis pedunculi (cerebral pudenculi) of midbrain
-Small fibres enter pons
-Pyramids of medulla oblongata

Question 20

Where do most fibres terminate of the corticospinal tract

Answer 20

At intermediate gray matter and Ventral horn of SC

Some fibres that originate from the parietal lobe, terminate in the dorsal horn SC

Question 21

Where does the LMN synapse with the UMN

Answer 21

In ventral root and then leaves SC

Question 22

What is the corticobulbar tract responsible for

Answer 22

Conscious control over eye, jaw and face muscles

Carries motor input important for swallowing and speech

Question 23

How is the Corticospinal tract formed

Answer 23

Arises from the lateral aspect of primary motor cortex
Fibres converge and pass through the internal capsule to the brainstem
Some fibres/corticospinal tract synapse with cranial nerves
Neurons terminate on the motor nuclei of cranial nerves

Question 24

What is a lesion cranial nerve nuclei called?

Answer 24

Bulbar lesion–> “bulbar palsy”

Question 25

What are lesions to axons of CNS called

Answer 25

Peripheral nerve lesion

Question 26

What is the final common pathway

Answer 26

Motor neurons from the ventral horn of the SC that project to the effectors for action
This includes motor nuclei of CNS