Midbrain

Question 1

Trochlear nucleus fibers

Answer 1

GSE - innervating superior oblique (intorsion and looking down)

Question 2

LMN lesions to trochlear

Answer 2

Externally rotated eye
Head tilts away from side of lesion
Diplopia
Downward gaze weakness in medial positon

Question 3

Lesion inferiro colliculus

Answer 3

NOT unilaterally deaf

Question 4

Substantia nigra

Answer 4

Dopaminergic region and basal ganglia related

Question 5

Periaqueductal gray

Answer 5

Descending pain modulation and limbic responses (associated with Raphe system)

Question 6

Oculomotor nucleus and its autonomic function

Answer 6

COnnects ot accessory oculomotor nucleus (edinger westphal) that provides PS innervation to sphincter pupillae and ciliaris

Question 7

UMN to oculomotor nucleuis

Answer 7

BIlateral contralateral frontal eye field

Question 8

LMN lesions to oculomotor

Answer 8

EYe deviates lateral
Weskness in elevation when abducted
Eye is down and out 
Diplopia 
Ptosis
Dilated
Inability to accommodate

Question 9

Red nucleus

Answer 9

Origin of rubrospianl

Will result in decerebrate posture

Question 10

Horizontal gaze muscles involved

Answer 10

Ipsilateral lateral rectus and contralateral medial rectus must work together

Question 11

Important pathway for gaze

Answer 11

MLF

Question 12

PPRF

Answer 12

Paramedian pontine reticular formation

Direct connection with abducens nucles

Receives connections from superior colliculus, frontal eye fields and vestbiular complex

Question 13

Things occuring when you gaze right

Answer 13

1) Right PPRF gets input from visual center and vestibular
2) Right PPRF excits ipsilateral abducens nucleus that innervate the ipsi lateral rectus to cause to gaze right
3) The right abducens has interneuonrs that send axons to contralateral MLF to innervate neurons in the left oculomotor nucles that allows left eye to look right

Question 14

Lesion of right abducens nerve

Answer 14

When asked to look right, right eye does not move
Left eye moves to the right

When asked to look left, both okay

Question 15

Lesion of right abducents nucleus or PPRF

Answer 15

WHen asked to look right, neither eye will move

WHen asked to look left, both look left

Question 16

Lesion of left MLF

Answer 16

When asked to look right, right eye will move but has nystagmus…left eye will NOT move

When asked to look left, both eyes look left

Question 17

Webers syndrome

Answer 17

Midbrain syndrome (paramedian portion of PCA and basilar)

Oculomotor nucleus - ipsi nerve palsy

Cerebral peduncle - contra UMN signs

Question 18

Benedikt’s syndrome

Answer 18

Branches of PCA and rostal artery (both paramedian and circumferential) - substantia nigra affected and contralateral tremors added