Brainstem; Midbrain

Question 1

midbrain-pons junction level characterized by

Answer 1

1 - decussation of trochlear n. w/in sup medullary velum
2 - narrow cerebral aqueduct (replaces 4thv)
3 - decussation of the superior cerebellar peduncle

Question 2

unilat lesion of the trochlear n

Answer 2

diplopia when looking down

ipsilat loss of motor control of superior oblique mm

Question 3

periaqueductal gray, stimulation of it

Answer 3

analgesic effect
act of serotonergic and adrenergic descending pathways that act spinal enkephalin interneurons which block trans of pain info in local spinal dorsal horn circuits

Question 4

locus ceruleus

Answer 4

main source of epinephrine

Question 5

lateral lemniscus

Answer 5

fibers from cochlear and sup olivary nuclei
contains aud info from both ears
terminats; inf colliculus

Question 6

tectospinal tract

Answer 6

origin; sup colliculus
term; high cervical spinal cord
function; reflex of turning head in resp to stimuli

Question 7

inf colliculus

Answer 7

relay for aud info
lateral lemniscus ends here
origin of brachium fibers ->medial geniculate nucleus (MGN)

Question 8

raphe nucleus

Answer 8

ventral part of periaqueductal gray

main source of serotonin

Question 9

superior cerebellar peduncle (SCP) decussates in midbrain, SCP consists mainly of

Answer 9

cerebellar efferent fibers fr deep cerebellar nuclei that project to contralateral red nucleus and ventral lateral nucleus of thalamus

Question 10

unilateral lesion of SCP

Answer 10

ipsilateral ataxia
hypotonia
dysmetria

Question 11

cerebral peduncle contains fibers of

Answer 11

corticospinal (middle third)
corticobulbar (more medial)
corticopontine

Question 12

unilat lesion of cerebral peduncle

Answer 12

contralat motor deficit in body

contralat drooping of the corner of the mouth

Question 13

location of the trochlear nucleus

Answer 13

midbrain

dorsal to MLF

Question 14

where do the fibers of the trochlear nuc decussate?

Answer 14

superior medullary velum

Question 15

trochlear n. innervates

Answer 15

contralat superior oblique mm

Question 16

unilat lesion of the trochlear nuc

Answer 16

diplopia when looking down

contralat loss of motor control of sup oblique mm

Question 17

input of sup colliculus

Answer 17

retina and visual cortices via brachium of sup colliculus

somatosensory and aud inputs

Question 18

output of the sup colliculus

Answer 18

to the pulvinar
controls reflex mvmt of orientation of the head via the tectospinal tract
involved in generation of saccadic eye mvmts via cntions w frontal eye field & pontine reticular formation

Question 19

medial geniculate nuclues

Answer 19

belongs to the diencephalon
thalamic relay for aud info
recieved inf from inf colliculus via brachium of inf colliculus and relays it to primary auditory cortex (Brodmann areas 41&42) via acoustic radiation

Question 20

brachium of sup colliculus

Answer 20

passes dorsally to medial geniculate nucleus

carries info from retina & vis corticis to sup colliculus

Question 21

superior cerebellar peduncle (in midbrain)

Answer 21

lateral to red nucleus
many fibers synapse w/in the red nucleus
rest go up to ventrolateral (VL) nuc of thalamus

Question 22

rubrospinal tract (in midbrain)

Answer 22

medial and ventral to red nucleus
origin; red nuc
term; C and upper T levels of SC
fun: facilitates distal flexor MN of Upper limbs

Question 23

fasciculus retroflexus (habenulointerpeduncular tract) in midbrain

Answer 23

medial to red nuclueus

connects habenula to interpeduncular nuc

Question 24

ventral tegmental area (VTA)

Answer 24

rich in dopaminergic neurons that project to nucleus accumbens (mesolimbic pathway) & to prefrontal cortex (mesocortical pathway)

Question 25

red nucleus

Answer 25

motor coordination upper limb flexors inputs: contralat deep cerebellar nuclei (via SCpeduncle) ipsilat motor cortex outputs; via central tegmental tract to inf olive for motor neuron

Question 26

substantia nigra

Answer 26

belongs to basal ganglia motor control 1 - pars compacta - melanin-pigmented dopaminergic neurons projection to striatum (parkinsons) 2 - pars reticulata - mostly GABAergic neurons -> to VA of thalamus, sup colliculus, & pedunculopontine nuc

Question 27

unilat lesion of oculomotor nuc

Answer 27

ophthalmoplegia lateral strabismus ptosis

Question 28

Edinger-westphal nucleus

Answer 28

pre-g parasymp fibers -> ciliary ganglia - short ciliary br of V3 -> constrictor mm and ciliary mm (constric of pupil and accomodation of lens)

Question 29

unilat lesion of Edinger-Westphal nuc

Answer 29

dilated pupil, loss of lens accomodation to near vision

Question 30

unilat lesion of oculomotor nerve

Answer 30

``` ophthalmoplegia lateral or external strabismus ptosis dilated pupil loss of lens accomodation loss of pupillary light reflex (efferent) ```

Question 31

oculomotor nerve emerges from

Answer 31

ventrally, from interpeduncular fossa

Question 32

pars compacta

Answer 32

component of the substantia nigra contains melanin-pigmented dopaminergic neurons -> striatum degeneration of these neurons is major pathology in Parkinson's disease

Question 33

pars reticulata

Answer 33

component of substantia nigra mostly GABAergic neurons projecting to ventral anterior (VA) nuc of the thalamus, sup colliculus, and pedunculopontine nuc

Question 34

pretectal area of the tegmentum of midbrain

Answer 34

recieves input from both eyes | invovled in pupillary light reflex

Question 35

posterior commissure

Answer 35

connects pretectal areas

Question 36

accessory oculomotor nuclei

Answer 36

present in pretectal area of midbrain several small nuclei along sides of periaqueductal gray imp for generation of vertical eye mvmt

Question 37

lesion of the accessory oculomotor nuclei

Answer 37

deficits in vertical gaze

Question 38

lateral geniculate nucleus

Answer 38

thalamic relay for visual info from retina | via optic nerve -> LGN - optic radiation-> primary visual cortex (brodmann area 17)

Question 39

pineal gland

Answer 39

melatonin production reg circadian rhythms melotonin prod stim by darkness and inhibited by light melotonin also has an antigonadotropic action