1. What are the seven major descending motor control pathways. Which three origi

ID: 3519585 • Letter: 1

Question

1. What are the seven major descending motor control pathways. Which three originate in the cortex? Which four come from brainstem nuclei?which are laterally descending pathways, and which descend medially? Briefly describe the general function of each (e.g. what part of the body they serve, and/or what type of motor control is mediated).

2.Describe the intrinsic circuitry of the basal ganglia (cerebral cortex to basal ganglia to thalamus to frontal cortex), including the direct and indirect paths.
How is this circuit disordered in a hypokinetic disorder, such as Parkinson’s disease, and in a hyperkinetic disorder, such as Huntington’s disease or
hemiballism?

Explanation / Answer

Question 1

Answer

The seven major descending motor control pathways are

1. Lateral corticospinal tract

2. Anterior corticospinal tracts

3. Corticobulbar tracts

4. vestibulospinal tracts

5. Reticulospinal tracts

6. Rubrospinal tracts

7. Tectospinal tracts

The three major descending motor control pathways originating from the cortex are

1. Lateral corticospinal tract

2. Anterior corticospinal tracts

3. Corticobulbar tracts

The four major descending motor control pathways comes from the brainstem nuclei are

1. vestibulospinal tracts

2. Reticulospinal tracts

3. Rubrospinal tracts

4. Tectospinal tracts.

The laterally descending pathways are

- Lateral corticospinal tract

- Corticobulbar tracts

- Rubrospinal tracts

Medially descending pathways are

- vestibulospinal tracts

- Reticulospinal tracts

- Tectospinal tracts.

Tract

Function

Lateral corticospinal tract

The motor control of skeletal muscles

Anterior corticospinal tracts

It also control the function of skeletal muscles

Corticobulbar tracts

These are also responsible for muscle control especially in neck and face

vestibulospinal tracts

These are involved in subconscious regulation of balance, posture and tone of muscles.

Reticulospinal tracts

It mainly concerned with reflex activity.

Rubrospinal tracts

Regulate the upper limb muscle tone and movement

Tectospinal tracts

They subconsciously regulate the upper limb response to vision and auditory stimuli and also regulate movement of eye, neck and head.