Corticobulbar Tract

Question 1

What two pathways are involved in cortical control of motor activity

Answer 1

• Corticospinal Tract/Pyramidal System

- Corticobulbar Tract

Question 2

What 4 pathways are involved in Brainstem centers that influence motor activity

Answer 2

• vestibulospinal tract
• reticulospinal tract
• rubrospinal tract
• tectospinal tract

Question 3

Cranial nerves (what are they and where are they located)

Answer 3

• motor and sensory innervation of the head and neck including special senses
• purely motor, purely sensory, mixed
• CN nuclei are located within the brainste

Question 4

CN V (motor nucleus of V)

Answer 4

Muscles of mastication

Question 5

CN VII (facial nucleus)

Answer 5

Muscles of facial expression

Question 6

CNX (nucleus ambiguus)

Answer 6

Muscles of soft palate, pharynx and larynx

Question 7

CN XI (accessory nuclesu)

Answer 7

sternocleidomastoid and trapezius

Question 8

CN XII (hypoglossal nucleus)

Answer 8

intrinsic and extrinsic muscles of the tongue

Question 9

think of the cranial nerves as analagous to

Answer 9

lower motor neurons

-the corticobulbar tract is the upper motor neuron that sends messages to the lower motor neurons which are the cranial nerves

Question 10

Corticobulbar Tract

Answer 10

• from the cortex to the brainstem (bulbar)
• one neuron: upper motor neuron
• projects to Lower motor neuron (LMN) in cranial nerve motor nuclei of the brainstem
• Function: controls muscles of the head, face and neck

Question 11

Corticobulbar Tract Route

Answer 11

• cerebral cortex
• corona radiata
• internal capsule
• Projection: corticonuclear fibers project through the posterior limb of the internal capsule (closer to the genu than CST fibers)
• termination: CN motor nuclei

Question 12

describe the innervation of the CN nuclei in terms of unilateral bilateral or contralateral

Answer 12

they are all bilateral innervation except CNVII and CN XII are contralateral

Question 13

Describe the quadrants of the face and their innervation

Answer 13

• upper part of the face receives bilateral innervation bc the upper part of the facial motor nuclei receives bilateral innervation
• but the lower part of the face actually receives contralateral motor innervation

So a person w a unilateral lesion in the corticobulbar tract would still have ability to move muscle of facial expression on the top of the face bc it is bilaterallly innervated……but on the bottom of the face they would have contralateral paralysis

Question 14

Bells Palsy vs. Corticonuclear (corticobulbar) tract lesions

Answer 14

Bells palsy would have paralysis on the entire half of the face contralaterally (LMN lesion)

Corticonuclear tract lesion would be paralysis on the contralteral face but only the lower half of the contralateral face. so they would only lose one quarter of the face

Question 15

How does the tongue deviate when there is a corticonuclear tract lesion

Answer 15

away from lesioned side. so to the contralateral side

Question 16

How does the tongue deviate when there is a peripheral lesion

Answer 16

towards the lesioned side (ipsilateral) “Lick your wounds”

Question 17

Pseudobulbar Palsy

Answer 17

bilateral lesion of upper motor neurons that make up the corticonuclear tract

Question 18

what is Pseudobulbar palsy characterized by and what are the possible causes

Answer 18

-characterized by-weakness of muscles involved in chewing, swallowing, speaking and loss of emotional control

Possible causes: -brainstem infarcts, ALS , Multiple Sclerosis