Ascending and Descending Pathways

Question 1

Where are the 3 synapses of the spino thalamic pathway?

Answer 1

1st = spinal cord
2nd = thalamus
3rd = somato-sensory cortex

Question 2

What does the spinal thalamic pathway carry?

Answer 2

Pain, temperature, crude touch

Question 3

What is the internal capsule?

Answer 3

A band of white matter in the cerebral hemispheres through which almost all tracts enter of leave the cerebral cortex

Question 4

What are the 3 synapses of the dorsal column medial lemniscus pathway?

Answer 4

1st = medulla
2nd = thalamus
3rd = somato-sensory cortex

Question 5

What are the purpose of the two tracts in the dorsal column medial lemniscus pathway?

Answer 5

Medial gracile tract - carry’s sensation from the lower body and lower limbs
Lateral cuneate tract - carry’s sensation from upper body and upper limb
division between the two at T6

Question 6

What does the dorsal column medial lemniscus pathway carry?

Answer 6

Discriminative touch, proprioception and vibration sense

Question 7

What does the corticospinal pathway do?

Answer 7

Carries voluntary motor commands and controls spinal reflexes

Question 8

What are the two axons directions in the corticospinal pathway?

Answer 8

85% has axons crossing sides in the ventral medulla to create lateral cortico-spinal tract
15% has cortico-spinal axons stay on the same side

Question 9

What does the primary motor cortex conatin?

Answer 9

upper motor neurones whose axons pass either to the spinal cord for excitation of lower motor neurons in the ventral horns or to brainstem cranial nerve motor nuclei for similar activation of their lower motor neurons

Question 10

How is lateral corticospinal tract terminated?

Answer 10

Via an interneuron to allow patterning of muscle groups at the cord level