16 - Brainstem I

Question 1

What are the 3 parts that make up the brain stem?

Answer 1

-midbrain (ventral to cerebral hemispheres, ‘deep’)
-pons (close association to cerebellum)
-medulla

Question 2

Where is the 4th ventricle?

Answer 2

-between the cerebellum (‘roof’) and the pons + medulla (‘floor’)

Question 3

What is all the brainstem?

Answer 3

-LMN associated with cranial nerves
-UMN (cell bodies and axons)
-ascending axons carrying proprioceptive info from the limbs
-pontine micturition centre
-neural circuitry associated with maintenance of consciousness
-neural circuitry associated with cardiac and respiratory function
-emetic center

Question 4

All CN arise from the:

Answer 4

-brain or brainstem
*paired structures

Question 5

What is the function of CN?

Answer 5

-motor and sensory innervation to the head and neck

Question 6

Trigeminal (CN V):

Answer 6

-motor: muscles of mastication
-sensory: skin of head/face
*pons

Question 7

Facial (CN VII):

Answer 7

-motor: muscles of facial expression
-sensory: rostral tongue, ear
*rostral medulla

Question 8

What nerves are for the innervation of extra-ocular muscles?

Answer 8

-oculomotor (CN III): M, D, V recti, V. oblique
-trochlear (CN IV): D. oblique
-abducens (CN VI): L. rectus

Question 9

What CN have LMN?

Answer 9

-III
-IV
-V
-VI
-VII

Question 10

What are the CN for special senses?

Answer 10

-I
-II
-VIII
*don’t have LMN

Question 11

Olfactory (CN I):

Answer 11

-extension of axons from olfactory bulb

Question 12

Optic (CN II):

Answer 12

-axon extensions FROM the eye

Question 13

Vestibulocochlear (CN VIII):

Answer 13

-hearing and balance

Question 14

What are the CN for motor to muscles of pharynx, larynx and tongue?

Answer 14

-IX
-X
-(XI)
-XII

Question 15

Where do CNs mostly emerge from and what does that mean for innervation?

Answer 15

-ventrolaterally
*innervate structures on IPSILATERAL (same) side of body
>sensory or LMN signs
-exception is the optic nerve

Question 16

What are the deficits to V and VII with a lesion to the brainstem? (LMN damage)

Answer 16

-flaccid muscles (+ no reflexes)
>difficulty chewing/prehension of food
>dropped jaw/drooping ears, lips
>inability to blink (palpebral or corneal reflex)
-rapid atrophy
>atrophy of temporalis changes head shape

Question 17

Palpebral reflex is testing:

Answer 17

-blinking
>sensory (V) (corneal reflex)
>motor (VII)

Question 18

What are the deficits to III, IV, VI with a lesion to the brainstem? (LMN damage)

Answer 18

-strabismus: abnormal eye position at REST
-VI damaged: medial strabismus (due to lateral rectus being damaged)
-IV damaged: ventral strabismus (dorsal oblique damaged)
-III damaged: lateral strabismus (only thing that has tone is VI (lateral rectus))

Question 19

What are the deficits to CN I, II, VIII with a lesion to the brain stem?

Answer 19

-SENSORY deficits ONLY
>NO LMN!
-I: try give them something to smell
-II: menus response (also VII)
-VIII: ‘clap’, electromagnetic test, maybe head tilt

Question 20

Cell body locations for IX, X XI:

Answer 20

-mid medulla

Question 21

Cell body locations for XII:

Answer 21

-caudal medulla

Question 22

What are the deficits to CN IX, X,XII with a lesion to the brain stem?

Answer 22

-difficulty swallowing
-gagging
-deviated tongue, due to flaccid muscles (pulled to side that is still innervated (ex. right side damaged=tongue to the left))
-stertor (loud breathing, due to vocal folds being in the way)