Week 4: Tracts

Question 1

The corticospinal tract is a ……. pathway responsible for …….. movements of the limbs and trunk

The corticospinal fibres are a collection of ….. that carry movement related information from the ….. (primarily the primary motor cortex) to the …… where it synapses with a motor neuron

The …….. is the major decussation or crossing site of the descending motor corticospinal fibres

It is located in the …… part of the base of the medulla ~ …..% of fibres cross and form this pyramidal decussation

After crossing the fibres form the ….. corticospinal tract that further descend to reach the …..

Fibres that do not cross the midline become the ……

Answer 1

1. Descending & voluntary
2. Axons, cerebral cortex & spinal cord
3. Pyramidal decussation
4. Anterior lower & 80-90%
5. Lateral & spinal cord
6. Anterior corticospinal tract

Question 2

The neurons that travel in the corticospinal tract are referred to as …….

They synapse on neurons in the spinal cord called …….. which exit the spinal cord at the level of the synapse

These lower motor neurons make contact with a skeletal muscle causing a ……

Given what we know we can say that the left brain controls the …… of the body

Answer 2

1. Upper motor neuron
2. Lower motor neuron
3. Contraction
4. Right side

Question 3

The corticobulbar tract connects……

Answer 3

The motor cortex in the cerebral cortex to primarily the brainstem

Question 4

Corticobulbar tract neurons regulate….

Answer 4

Voluntary movements of the face head and neck

Question 5

Corticobulbar neurons terminate on …….. within the brainstem …… or …… which subsequently synapse on the brain stem nuclei from which the cranial nerves originate

Answer 5

Cranial nerves
Motor nuclei
Intermediate neurons

Question 6

What type of pathway is the dorsal column-medial lemniscus? Sensors for …… & ….. are stimulated at the periphery

Answer 6

Sensory pathway
Fine touch & proprioception

Question 7

How do the signals travel with the dorsal column medial lemniscus tract?

Answer 7

The signal travels via sensory neurons to the spinal cord

At the spinal cord this doesn’t synapse immediately and travels up the ipsilateral side of the spinal column to the nucleus cuneatus and the medulla

This neuron decussates or crosses to the contralateral side, travels up the medial lemniscus to the thalamus

In the thalamus it synapses with its tertiary neuron and goes to the cortical areas such as the primary sensory cortex in the post central gyrus

Question 8

The Spinothalamic tract is an ….. pathway that is responsible for the transmission of pain, temperature and crude touch

Answer 8

Ascending
Transmission of pain, temperature & crude touch

Question 9

Spinal neurons of this pathway enter the spinal cord and directly synapse on a neuron and immediately crosses the spinal cord where they ascend to the ……

In the thalamus they synapse with their tertiary neuron and go to cortical areas such as the …… IE the postcentral gyrus

Answer 9

1. Thalamus
2. Primary sensory cortex