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Term IV: Neuro > Midbrain > Flashcards

Flashcards in Midbrain Deck (24):

Which cranial nerve arises from midbrain dorsally? Ventromedially?

Dorsally - IV
Ventromedially - III


Two characteristic levels of midbrain

Inferior and superior colliculus


Two major modulating nuclei of midbrain

Substantia nigra
Red nucleus


Inferior Colliculus

Important for _____ pathways.

Inputs from ______ that originate from ___ and ____

Outputs to _____


Inputs from: Lateral lemniscus - from superior olivary nucleus of pons and cochlear nuclei of medulla

Outputs to: medial geniculate nucleus of thalamus


What area surrounding cerebal aqueduct is rich in enkephalins for modulation of autonomics and pain?

Which colliculi is it present in?

Periaqueductal Grey

Both inferior and superior colliculi


In inf colliculus:

Controls superior oblique muscle of eye; axons exit dorsally just inferior to inf. colliculus

Nucleus of CN IV


In inf colliculus:

Feeds from vestibular nuclei to nucleus of IV; located immediately ventral to IV

MLF - medial longitudinal fasciculus


In inf colliculus:

Contains reticular formation - serotonin fibers which regulate wakefulness

Central tegmental area


In inf colliculus:

Where does decussation of superior cerebellar peduncle travel?

To red nucleus and ventrolateral nucleus of thalamus


In inf/sup colliculus:

Medial 1/5 of crus cerebri?

Frontopontine fibers


In inf/sup colliculus:
Middle 3/5 of crus cerebri?

Corticobulbar (medially) and corticospinal (laterally) fibers


In inf/sup colliculus:
Lateral 1/5 of crus cerebri from what lobes

Parietal, occipital, and temporal lobes to pontine nuclei


In inf/sup colliculus:
Medial part of substantia nigra that has dopamine fibers to basal ganglia?

Pars compacta- important in Parkinson's


In inf/sup colliculus:

Lateral part of substantia nigra that has GABA fibers to thalamus

Pars reticulata


If you see this nucleus, you know you are at the level of superior colliculus.

Red nucleus


Superior Colliculus

Important for ____ pathways.

Inputs from ____.
Outputs to ____ via ____ for coordination of visual tracking.

Visual pathways

Inputs: retina
Outputs: to cervical muscles via tectospinal tract


In sup colliculus:

- Contains both somatic GSE and autonomic GVE fibers; axons exit ventromedially, anterior to pons

Nucleus of CN III


In sup colliculus:

- Feeds from vestibular nuclei to nucleus of III, located immediately ventral to III

MLF - medial longitudinal fasiculus


In sup colliculus:

Important source of dopaminergic fibers to forebrain, adjacent to pars compacta

Ventral tegmental area


In sup colliculus:

Receives fibers from superior cerebellar peduncle and projects to flexor muscles and inf. olivary nucleus

Red nucleus


What two structures do you see at extreme rostral end of midbrain?

Pretectal area:

- Edinger Westphal nucleus (presynaptic parasymp fibers of III to ciliary ganglion)
- Posterior commissure for coordinated mvt of both eyes


What syndrome?

Ipsilateral oculomotor paralysis w/ contralateral upper motor neuron lesion. Results from vascular insufficiency in medial aspect of midbrain at sup. colliculus.

Weber's syndrome


What syndrome?

Ispilateral III paralysis w/ contralateral tremor and possible contralateral somatosensory loss. Results from vascular lesion to III and red nucleus and superior cerebellar peduncle and medial lemniscus (dorsal columns), as well as possible spinothalamic tract.

Benedikt's syndrome


What syndrome?

Pineal tumor affects pretectal area and posterior commissure. Results in upward gaze paralysis - vertical gaze - large pupil and abnormal elevation of upper eyelid, paralysis of accomodation

Gaze palsy - Parinaud's syndrome