Internal Anatomy of Midbrain

Question 1

Answer 1

tectum

Question 2

Answer 2

superior colliclus

Question 3

Answer 3

brachium of inferior collilculus

Question 4

Answer 4

crus cerebri

Question 5

Answer 5

tegmentum of midbrain

Question 6

Answer 6

cerebral aqueduct

Question 7

Answer 7

Cerebral Peduncle (crus cerebri + grey matter of the tegementum)

Question 8

Answer 8

prectal area

above the brachium

Question 9

Answer 9

inferior colliculus

function: hearing, localization of sound
pathology: subtble deficits in localizing source of sound

Question 10

Answer 10

Lateral lemniscus

function: hearing
pathology: no obvious sx from unilateral X

Question 11

Answer 11

ALS /Spiunothalmic

function: carries propathic (simple touch, pressure, pain and temp from the OPPOSITE side of the body)
pathology: contralateral loss of propathic sensation beginning 2 segments below the lesion.

Question 12

Answer 12

medial lemniscus

function: epicritic somatosensory for trunk and limbs on the OPPOSITE SIDE
pathology: loss of 2 point, vibration, position sense, asterognosis, shuffling gait

Question 13

axons going through here

Answer 13

axons of the decussation of the superior cerebellar peduncle

Question 14

Answer 14

Decussation of the superior cerebellar peduncle

function: carries signals of disparate function between cerebellum and brain stem
pathology: cerebellar signs: ataxia, intention tremor

Question 15

Answer 15

corticospinal tract

function: motor control from cortex to motor neurons

Question 16

Answer 16

medial longitudinal fascilus

function: coordinates head and eye position
pathology: contralateral eye cannot adduct for conjugate gaze, but can adduct during convergence

Question 17

Answer 17

Nucleus of CN 4

function: rortates the eye and assists in abduction and downward movement
pathology: subtle effects in OPPOSITE EYE

slightl difficulty converging and looking downwards

Question 18

Answer 18

Periaqueductal Gray

function: pain sensation, rich in endorphin receptors
pathology: in animals, blocks the benefit of analgesics

Question 19

Answer 19

cerebral aqueduct

Question 20

Answer 20

superior colliculus

functions: 1. sensory: vision, perhaps to focus visual attension on a sector of space
2. motor: controls roientaing movements of head and neck
pathology: subtle deficits..
1. partial neglect of contralateral visual space
2. slightly smaller saccades OPPOSITE the lesion

Question 21

Answer 21

bracium of the inferior colliculus

function: conveys auditory signals to the midbrain to the thalamus
pathology: UNK (bilateral X is rare)
connections: inferior colliculus to the MGN

midbrain section, hole without the frog eyes

Question 22

Answer 22

ALS/Spinothalamic tract

function: carries protopathic info
pathology: contralateral loss of protopathic sensation beginning two segments below the lesion

Question 23

Answer 23

medial lemniscus

pathology: loss of 2 point, vibration, position sense, asterogenosis, shuffling gait

Question 24

Answer 24

Decussation of superior cerebellar peduncle

pathology: cerebellar signs: ataxia, intentional tremor

Question 25

Answer 25

crus cerebri

function: cortical control of movement and some descending gating of sensory signals
pathology: loss of independent finger movement, slower rxn times, sight weakness

Question 26

Answer 26

Corticospinal tract

Question 27

Answer 27

medial longitudinal fasiculus

Question 28

Answer 28

Trochlear nucleus

funtion: rorates eye and assists in abduction and downward movement
pathology: subtle effects on OPPOSITE eye

slight difficulty converging and looking downward

Question 29

Answer 29

superior colliculus

function: 1. sensory: vision, perhaps to focus visual attn on a sector of space
2. motor: controls orienting movements of the head and neck
pathology: subtle deficits:
1. partial neglect of OPPOSITE visual space
2. slightly smaller saccades directed to side opposite of lesion

Question 30

Answer 30

medial lemniscus

function: epicritic somatosensory for trunk and limbs on opposite side

Question 31

Answer 31

anterolateral system/spinothalamic tract

function: carries propathic information (simple touch, pressure, pain, and temperature)

Question 32

Answer 32

substantia nigra

function: pars compacta: skeletal movement, complete dopamine synthesis

paras reticula: skeletal and eye movements

Question 33

Answer 33

Crus cerebri

function: cortical control of movement and some descending gating of sesnory signals
pathology: loss of indepdentent finger movement, slowed rxn times, slight weakness

Question 34

Answer 34

cerebellothalamic fibers

Question 35

Answer 35

Red nucleus

fnction: skeletal movement
pathology: probably no obvious sx from isolated pathology

Question 36

Answer 36

Medial geniculate nucleus (body)

function: hearing
pathology: lose ability to decode patterns of sound

errors in localizing source of sound

Question 37

Answer 37

CN III

function: rorates eye upward, downward, toward nose

constricts the pupil

accomidation of the lens for near vision

pathology: external strabisimus: eye deviated OUTWARD and cannot move nasally, up, or down

pupil is dilated and cannot constrict (due to pathology of near endinger westphal)

Question 38

Answer 38

CN III

function: rorates eye upward, downward, toward nose

constricts the pupil

accomidation of the lens for near vision

pathology: external strabisimus: eye deviated OUTWARD and cannot move nasally, up, or down

pupil is dilated and cannot constrict (due to pathology of near endinger westphal)

Question 39

Answer 39

Nucleus Raphe Dorsalis

Question 40

Answer 40

brachium of the superior collculus

no isolated pathology described.