BS and cranial N exam Flashcards
CN 3 Palsy
complete:
- Mydriasis
- Ptosis
- Extraocular paralysis of m. innervated by III
- eye will lie down and out
(unopposed lateral rectus and superior oblique)
Horners syndrome
- ips ptosis
- miosis
- anhydrosis
Superior Oblique palsy
Eye will elevate as it turns medially
- pt will compensate by tilting head
(when the eye is pointed medially, SO is a depressor)
Paramedian Pontine Reticular Formation (PPRF)
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)
- motor neuron
- ( that will send axons from abducens n. to ips lateral rectus) - interneuron
- (fr abducens n to across midline and to MLF → occulomotor nucleus → medial rectus)
Unilateral demyelination of MLF commonly found in which disorder?
Multiple sclerosis
- (internuclear opthalmoplegia)
(but MLFs are generally suceptible to demyelinating diseases)
Unilateral demyelination of MLF produces what condition? How to test that the occulomotor comples is unaffected by the lesion?
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
Jaw jerk reflex
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)
Corneal blink reflex
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)
Where can you locate the principal sensory nucleus of V?
Mid pons
- lateral to the motor nucleus of V
(and adjacent to middle cerebellar peduncle)
Trace motor command of V
Mastication
- Primary motor cortex
- face area of precentral gyrus → descend - main motor nucleus of V in pons →
- muscles of mastication
Which nucleus houses proprioception from the jaw joint and muscles of the face?
Mesencephalic nucleus Trigeminal (Like DRG in midbrain)
Rostral due to embryologic development - not in trigeminal ganglion like fine touch, P, Vib
Trace fine touch, P, Vibration from face
Trigeminal ganglion →
main sensory nucleus of V in pons →
VPM of Thalamus →
Somatosensory Cortex
Trace Pain and Temp from face
Trigeminal ganglion → enter pons and descends → spinal nucleus of V → VPM of thalamus → Postcentral gyrus (somatosensory cortex)
The corticospinal pathway to the body is like _________ to the face
Trigeminal division of corticobulbar pathway
The 2° cell body of the corticospinal pathway are the _________.
The 2° cell body of the Trigeminal division of corticobulbar pathway are the _________.
CS: alpha motor neuron in ventral horn of sc
CB: main motor nucleus of V (in pons)
Fine touch, Vib, P
DCML pathway
Trigeminothalamic pathway of face
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
Pain and temp
Spinalthalamic pathway
Trigeminothalamic pathway
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
Pupillary light reflex
Afferent and Efferent
Afferent:
Optic nerve
Efferent:
Parasymp division of II (EWN to ciliary ganglion)
Gag reflex
Afferent and Efferent
Afferent:
Glossopharyngeal nerve
Efferent:
Vagal division of nucleus ambiguous
Which slice is the facial nerve nucleus found in? How to identify?
Lower pons
Ventrolateral to abducens nucleus
Axons curve around abducens nucleus before exiting pons at cerebello-pontine angle (just below middle cerebellar peduncle)
Rostral and caudal half of facial nucleus innervates which parts of the face?
Rostral: upper half of face
Cauda: lower face
Lesion to UMN as it traverses the internal capsule will cause which facial palsy?
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)
Peripheral facial palsy
Entire half of the face is weak.
- upper and lower MN involves injury to facial nucleus or nerve (LMN)
Conductive Hearing loss
- Rinne test
- Weber test
Rinne (mastoid)
nl: AC>BC
conductive: BC>AC
Weber:
louder on affected side
Vestibulo-ocular reflex
- what happens with a R sided vestibular lesion?
turning head to right.
Eyes go to the left at same angular acceleration
- Left beating nystagmus
Testing CN 9 and 10
- their nuclei enter and exit nuclei found in which slice?
Upper mid medulla.
-Uvula points away from deficit (muscle is weak so it cant pull on that side)
Taste, pain, temp, posterior 1/3 of tongue
9th nerve - glossoph.
Nucleus ambiguus:
general direction and fxn
upper medulla (loc. inf + ventral) to Inf. salivary nucleus.
fxn:
innervate skeletal muscle of the stylopharyngeus, larynx, pharynx
-phonation and gagging
IX and X
UMN damage to CN12 vs Injury to nucleus or nerve itself
UMN: tongue deviates towards side of lesion
LMN: atrophy and fasiculations (like other LMN)
