Midbrain

Question 0

CN 3

Answer 0

Sends GVE pregang para symp to sphincture pupillae and ciliary muscles. They synapse in the ciliary gang.

Question 1

CN 3

Answer 1

Primarily GSE fibers, innervates muscle
So of the eye.
Exits midbrain in the interpeduncular fossa anteriorly.

Question 2

CN 4

Answer 2

Exits posterior lay at the level of the inf colliculus. Carries GSE fibers to the sup oblique muscle of the eye.

Question 3

Superior colliculus

Answer 3

Involved in the conjugation of eye movement, reflex closure of the eye and accomodation by focussing eye at short range.

Question 4

Sup colliculus tracts

Answer 4

Receives afferent through superior bra him pathway
Axons from retinal ganglion
Corticotectal fibers from the occipital and frontal lobes.

Question 5

Sup colliculous efferent a

Answer 5

Tectobulbospinal tracts: tectobulbar- to nuclei controlling eye movements reflex eye closure.
Tectospinal- crossed to spinal cord for tracking of objects in the visual field.

Question 6

Inferior colliculus

Answer 6

Related to auditory pathway, tonotypically organized, coordinates auditory reflexes through connections with sup coll and tectospinal tract. Coordination of auditory, neck and eye movements.

Question 7

Inf coll

Answer 7

Afferents from the lateral lemniscus which is from the primary cochlear nuclei
Efferent To the geniculate nucleus of the thalamus via inferior brachium.

Question 8

Red nucleus

Answer 8

Main afferents- from cerebellar nuclei, corticorubral fibers which control motor fnxns
Main efferents-rubrospinal tract, flexor biased projection to the upper limb, major eff also go to the thalamus, cerebellum and olivary complex where they participate in cerebellar fnxns

Question 9

Substantial nigra

Answer 9

Contains pars compacts and reticulata, c has dopamine and is involved in Parkinson’s payhology while r doesn’t. Though r and c are interconnected.

Question 10

Ventral tegmental area

Answer 10

Contains dopaminergic neurons and is associated with reward system, found between sub nig and red nucleus

Question 11

Periaquaductal grey

Answer 11

Appears to be involved in modulating pain, receives a broad range of fibers.

Question 12

Lateral lemniscus

Answer 12

Ends at the level of the inferior colliculus, lat lemn is a continuation of the cochlear nuclei.

Question 13

Pretectum

Answer 13

Located rostral to the sup col and contains five nuclei related to visual fnxn
Major area involved in the pupillary light reflex, only large lesions seem to impair this reflex

Question 14

Vertical gaze center

Answer 14

is located just rostral to the midbrain pretectum. Nuclei communicate through the posterior commissure

Question 15

Blood supply to the midbrain

Answer 15

Quadrageminal a
Superior cerebellar a
Ant choroidal
Med posterior choroidal a