Descending Motor Pathways

Question 1

Where do the pyramidal tracts originate?

Answer 1

Sensory cortex

Question 2

From where does the corticospinal tract receive input? (4)

Answer 2

Primary motor cortex
Premotor cortex
Supplementary motor area
Somatosensory area

Question 3

What are the pyramidal tracts?

Answer 3

Corticospinal tract (voluntary movement of body)
Corticobulbar tract (voluntary movement of head and neck muscles)

Question 4

Describe the 2 routes taken by the corticospinal tract.

Answer 4

LATERAL CORTICOSPINAL TRACT
85%
Decussates in the medulla
Terminates in all spinal segments

ANTERIOR CORTICOSPINAL TRACT
15%
Decussates at the segmental level of innervation
Terminates in cervical and upper thoracic spinal segments

Question 5

What are the 2 exceptions to the rule that upper motor neurons in the corticobulbar pathway inner ate the cranial nerves bilaterally?

I.e. These only have contralateral innervation

Answer 5

Facial nerve (CN7)

Hypoglossal nerve (CN12)