Corticobulbar tract

Question 1

What is the corticobulbar tract

Answer 1

Connects cerebral cortex to the motor nuclei of cranial nerves (except CN 3, 4, 6)

Question 2

Where is the origin of the corticobulbar tract + bloodsupply

Answer 2

lower 1/3 of the precentral gyrus (broadman area 4)

middle cerebral aa

Question 3

Path of corticobulbar tract thru white matter and midbrain

Answer 3

enter into internal capsul (genu) supplied by lenticostriate aa (br of middle cerebral)

will travel just medial to corticospinal tract thru midbrain (supplied by post cerebral aa)

Question 4

What does the corticobulbar tract target in the pons

Answer 4

targets trigemenial and facial nerve

Question 5

How does the corticobulbar tract inn the trigeminal n and clinical app

Answer 5

gets billateral inn (will not see functional deficit because of this bilateral inn)

Question 6

how is the facial nerve innervated by the corticobulbar tract

Answer 6

rostral part gets bilateral inn (supplies upper face)

caudal part gets contralat inn (supplies lower face)

Question 7

What does the corticobulbar tract target in the medulla and clinical app

Answer 7

ambigous nucleus (CN 9, 10, 11) bilateral inn- wont see functional deficit

also targets hypoglosal- bilateral inn but contralaterally dominate**

Question 8

What does the last set of axons of the corticobulbar tract target in the spinal cord

Answer 8

motor nucleus of accessory nerve (11)

Question 9

Lesion in internal capsul (genu) will likely cause deficits on what side

Answer 9

on contralateral side

Question 10

lesion in pons will predominantly cause what lesion

Answer 10

no deficit to masciatory mm (Bilat inn)

-Contralateral lower face will be affected

Question 11

What will a lesion in medulla likely cause

Answer 11

-likely not affect ambigous (Bilateral inn)

Motor nucleus of hypogossal- contralaterally dominant so will see weakness and deviation to affected side

Question 12

Afferent input to motor nucleus of trigeminal (4)

Answer 12

1. Bilateral corticobulbar fibers
2. Sensory from mesencephalic nucleus of CNV
3. Sensory from spinal trigeminal tract
4. CNVIII from cochlear nerve

Question 13

Efferent of motor nucleus of trigeminal

Answer 13

CNV to mm of mastification and small mm

Question 14

What will occur in a LMN lesion in the facial nerve

Answer 14

full side of face will droop

Question 15

When you see only the lower part of the face drooping where is the lesion likely

Answer 15

CL pre central gyrus (lower part) or Genu of int capsul

Question 16

Aferent into the ambigous n (2)

Answer 16

1. BL corticobulbar

2. Spinal trigeminal tract and solitary nucleus associated w CNX

Question 17

Efferent of ambigous nucleus (3)

Answer 17

1. rostral CN 9
2. Middle part CNX
3. Caudal part CNXI

Question 18

You see deviation of ulula to R and L soft palate droopy where is the lesion

Answer 18

left vagus nerve palsy (LMN)

Question 19

Corticobulbar fibres to motor nucleus of CNXII afferent and efferent

Answer 19

afferent- BL corticobulbar fibres but CL dom

Efferent- mm of tongue

Question 20

If you stick out tongue and dev to left and has atrophy where is the lesion

Answer 20

Left hypoglossal nerve palsy (LMN)

Question 21

If you stick out tongue and dev to left but no atrophy where is the lesion likely

Answer 21

R UMN/ corticobular lesion