BS and cranial N exam

Question 1

CN 3 Palsy

Answer 1

complete:

1. Mydriasis
2. Ptosis
3. Extraocular paralysis of m. innervated by III

• eye will lie down and out
  (unopposed lateral rectus and superior oblique)

Question 2

Horners syndrome

Answer 2

1. ips ptosis
2. miosis
3. anhydrosis

Question 3

Superior Oblique palsy

Answer 3

Eye will elevate as it turns medially
- pt will compensate by tilting head

(when the eye is pointed medially, SO is a depressor)

Question 4

Paramedian Pontine Reticular Formation (PPRF)

Answer 4

Coordinates response of neurons controlling lateral rectus on 1 side with those controlling medial rectus on the other side

Composed of neurons that innervate two cells located within the abducens nucleus (in lower pons)

1. motor neuron
   - ( that will send axons from abducens n. to ips lateral rectus)
2. interneuron
   - (fr abducens n to across midline and to MLF → occulomotor nucleus → medial rectus)

Question 5

Unilateral demyelination of MLF commonly found in which disorder?

Answer 5

Multiple sclerosis
- (internuclear opthalmoplegia)
(but MLFs are generally suceptible to demyelinating diseases)

Question 6

Unilateral demyelination of MLF produces what condition? How to test that the occulomotor comples is unaffected by the lesion?

Answer 6

Internuclear opthlamoplegia

• lateral gaze to side opposite lesion results in failure of ips eye to follow medially
  (resulting diplopia induces nystagmus in contralateral eye that is gazing laterally)
• Convergence test (both eyes will look medially, including one that just failed to do so on lateral gaze

Question 7

Jaw jerk reflex

Answer 7

Downward tapping of jaw (using reflex hammer) causes bilateral contraction of masseter (close mouth)

• Afferent: mesencephalic nucleus of V (stretch receptors in masseter)
• Efferent: decends to main motor nucleus of V (m of mastication)

Question 8

Corneal blink reflex

Answer 8

Cornea is touched by foreign object → both eyes blink

• Afferent: spinal nucleus of V
• Efferent: motor nucleus of VII

(V1 branch of trigem nerve for input, and facial nerve for output)

Question 9

Where can you locate the principal sensory nucleus of V?

Answer 9

Mid pons
- lateral to the motor nucleus of V
(and adjacent to middle cerebellar peduncle)

Question 10

Trace motor command of V

Answer 10

Mastication

1. Primary motor cortex
   - face area of precentral gyrus → descend
2. main motor nucleus of V in pons →
3. muscles of mastication

Question 11

Which nucleus houses proprioception from the jaw joint and muscles of the face?

Answer 11

Mesencephalic nucleus Trigeminal (Like DRG in midbrain)

Rostral due to embryologic development - not in trigeminal ganglion like fine touch, P, Vib

Question 12

Trace fine touch, P, Vibration from face

Answer 12

Trigeminal ganglion →
main sensory nucleus of V in pons →
VPM of Thalamus →
Somatosensory Cortex

Question 13

Trace Pain and Temp from face

Answer 13

Trigeminal ganglion →
enter pons and descends →
spinal nucleus of V →
VPM of thalamus →
Postcentral gyrus (somatosensory cortex)

Question 14

The corticospinal pathway to the body is like _________ to the face

Answer 14

Trigeminal division of corticobulbar pathway

Question 15

The 2° cell body of the corticospinal pathway are the _________.
The 2° cell body of the Trigeminal division of corticobulbar pathway are the _________.

Answer 15

CS: alpha motor neuron in ventral horn of sc

CB: main motor nucleus of V (in pons)

Question 16

Fine touch, Vib, P

DCML pathway

Trigeminothalamic pathway of face

Answer 16

DCML
1° cell body: DRG
2° cell body: Nucleus gracilis/cuneatus
3° cell body: VPL of thalamus

TT:
1° cell body: trigeminal ganglion
2° cell body: main sensory nucleus of V
3° cell body: VPM

Question 17

Pain and temp

Spinalthalamic pathway

Trigeminothalamic pathway

Answer 17

ST
1° cell body: DRG
2° cell body: Nucleus proprius
3° cell body: VPL

TT
1° cell body: trigeminal ganglion
2° cell body: Spinal nucleus of V
3° cell body: VPM of thalamus

Question 18

Pupillary light reflex

Afferent and Efferent

Answer 18

Afferent:
Optic nerve

Efferent:
Parasymp division of II (EWN to ciliary ganglion)

Question 19

Gag reflex

Afferent and Efferent

Answer 19

Afferent:
Glossopharyngeal nerve

Efferent:
Vagal division of nucleus ambiguous

Question 20

Which slice is the facial nerve nucleus found in? How to identify?

Answer 20

Lower pons

Ventrolateral to abducens nucleus
Axons curve around abducens nucleus before exiting pons at cerebello-pontine angle (just below middle cerebellar peduncle)

Question 21

Rostral and caudal half of facial nucleus innervates which parts of the face?

Answer 21

Rostral: upper half of face

Cauda: lower face

Question 22

Lesion to UMN as it traverses the internal capsule will cause which facial palsy?

Answer 22

Central facial palsy

UMN from motor cortex:

• Innervates rostral half of nucleus bilateraly
• Innervates contralateral caudal facial nucleus

(lesion to UMN as it traverses internal capsule will cause weakness of contralateral lower face only)

Question 23

Peripheral facial palsy

Answer 23

Entire half of the face is weak.

- upper and lower MN involves injury to facial nucleus or nerve (LMN)

Question 24

Conductive Hearing loss

• Rinne test
• Weber test

Answer 24

Rinne (mastoid)

nl: AC>BC
conductive: BC>AC

Weber:
louder on affected side

Question 25

Vestibulo-ocular reflex

• what happens with a R sided vestibular lesion?

Answer 25

turning head to right.
Eyes go to the left at same angular acceleration

• Left beating nystagmus

Question 26

Testing CN 9 and 10

- their nuclei enter and exit nuclei found in which slice?

Answer 26

Upper mid medulla.

-Uvula points away from deficit (muscle is weak so it cant pull on that side)

Question 27

Taste, pain, temp, posterior 1/3 of tongue

Answer 27

9th nerve - glossoph.

Question 28

Nucleus ambiguus:

general direction and fxn

Answer 28

upper medulla (loc. inf + ventral) to Inf. salivary nucleus.

fxn:
innervate skeletal muscle of the stylopharyngeus, larynx, pharynx
-phonation and gagging
IX and X

Question 29

UMN damage to CN12 vs Injury to nucleus or nerve itself

Answer 29

UMN: tongue deviates towards side of lesion

LMN: atrophy and fasiculations (like other LMN)