Midbrain

Question 1

1.2 Components of Tectum

Answer 1

Corpora Quadrigemina w/ superior and inferior colliculi

Question 2

Superior vs. Inferior Colliculi

Answer 2

Vision and associate w/ lateral geniculate vs. hearing and associate w/ medial geniculate of thalamus

Question 3

3 Large Visible Contents of Tegmentum

Answer 3

Cerebral peduncle
Substantia nigra
Red nucleus

Question 4

Cerebral peduncle

Answer 4

Contains all corticospinal/pontine/bulbar descending motor fibers so contralateral. Also somatotropic

Question 5

Substantia nigra

Answer 5

Lots of melanin deposited so it looks black, but spreads DA

Question 6

14 Contents of Midbrain

Answer 6

III
Ventral tegmental area
Substantia nigra
Medial lemniscus
Superior colliculus and inferior
Periaqueductal gray
Trigeminothalamic tract
Cerebral aqueduct
Spinothalamic tract
Medial longitudinal fasiculus
Cerebral peduncle
Red nucleus
Trochlear nucleus

Question 7

Ventral Tegmental Area (VTA)

Answer 7

Medial aspect of substantia nigra under peduncle. Also contains lots of DA but instead of going to basal ganglia spreads all throughout brain like Raphe or ceruleus

Question 8

Periaqueductal Gray

Answer 8

Gray nuclei around cerebral aqueduct that do pain/autonomic and reticular area shit

Question 9

Branchium

Answer 9

Arm of colliculi that head to geniculate

Question 10

Pain Gating

Answer 10

Periaqueductal gray sends fibers to Raphe which send it to dorsal horn of spinal cord to modulate/override pain w/ descending signals

Question 11

2 Arteries Around III

Answer 11

Superior cerebellar and posterior cerebral a.s, so they can compress it

Question 12

3 Parasympathetic Effects of III

Answer 12

Pupillary constriction
Acommodation
Nucleus of Edinger-Westphal next to III nucleus, so lose one and you lose both

Question 13

Different Levels of the Two CNs

Answer 13

III at level of superior colliculus and IV and level of inferior

Question 14

Trochlear Nerve (IV) Path

Answer 14

Exits posterior and immediately crosses to innervate contralateral superior oblique muscle. So lesion nucleus its contralateral but nerve probably ipsi

Question 15

3 Signs of III Lesion

Answer 15

Pupil dilated bc lack of parasymp
Always looks towards lesion w/ that eye
Turn his head so always looking in direction of lesion to avoid diplopia

Question 16

Sign of IV Lesion

Answer 16

Head tilted opposite direction of lesion to compensate

Question 17

Parkinson’s

Answer 17

DA Loss in substantia nigra

Question 18

Weber’s Syndrome

Answer 18

Caused by stroke in branch of posterior cerebral or basilar a.
Ipsilateral loss of III and contralateral loss of motor control of skeletal muscles