Brainstem III Flashcards
trochlear nerve: innervates what mm?
superior oblique muscle
trochlear nerve to superior oblique mm: what nucleus?
trochlear nucleus to contralateral SO mm
where does the trochlear nerve decussate? where does it exit?
superior medullary velum; exits dorsally to subarachnoid space, cavernous sinus, superior orbital fissure into the orbit to SO
SO paralyzation is contralateral or ipsilateral if the trochlear nucleus is damaged?
contralateral. if trochlear nerve is damaged after decussation its ipsilateral.
signs of lesions of trochlear nerve/nucleus
can’t look down and in (extorsion), vertical diplopia when reading/walking down stairs, head tilt + chin down contralaterally to affected SO
possible causes of trochlear lesion
trauma, hydrocephalus, hemorrhage, infarct.
if the trochlear nerve is damaged at decussation, will the signs be contralateral or ipsilateral?
bilateral SO problem
if the trochlear nerve is damaged after decussation, is the sign ipsilateral or contralateral?
ipsilateral
oculomotor nerve- somatic motor function: which nucleus? to which muscles?
oculomotor nucleus; to levator palpebrae superioris, extrinsic eye muscles except LR6SO4
oculomotor nerve- visceral motor function: which nucleus? to which structures?
nucleus of Edinger-Westphal- parasympathetics to ciliary ganglion on to pupillary constrictor and ciliary body
symptoms of oculomotor palsy; common clinical cause?
down and out mydriasis (pupil dilation), full ptosis; posterior cerebral artery stroke
difference between Horner’s syndrome and an oculomotor nerve lesion
Horners: SYMPATHETICS lost: partial ptosis, miosis, anhydrosis
CN III: SOMATIC MOTOR LOST: full ptosis, down and out, PARASYMPATHETICS LOST: mydriasis (dilated pupil)
CNs with parasympathetic function
3, 7, 9
function of posterior commissure of midbrain
pupillary light reflexes
periaqueductal grey function
pain
function of substantia nigra of midbrain
dopamine, motor system
function of ventral tegmental area of midbrain
dopamine, limbic system
function of lateral lemniscus of the midbrain
hearing
the optic nerve special somatic sensory: what ganglion? to what structure in the brain?
retinal ganglion cells to lateral geniculate body in the thalamus
*what cells myelinate the optic nerve?
oligodendroglia
what CNs do the pupillary light reflex?
II and III
pathway of pupillary light reflex, and reason why both eyes will blink
sensory via optic nerve to the pretectal nucleus in the midbrain, synapses with interneuron that bilaterally innervates oculomotor nerve on both sides via the Edinger-Westphal nucelus
what part of the brain is the olfactory nerve located in? what cells do special visceral sensory of olfactory nerve travel on?
telencephalon; bipolar neurons olfactory epithelium to the olfactory bulb!
unique property of olfactory nerve; an olfactory hallucination
it can regenerate; smell of burning rubber
what fibers are the sensory component of motor cranial nerves III, IV, VI, XII? to what nucleus do they go through?
proprioceptive fibers to mesencephalic nucleus of V
CNs 7, 9, 10, 1 for taste and olfactory (special visceral sensory) go through which nucleus?
solitary nucleus, along with 9, 10 for internal organs general visceral sensory
structures supplied by the anterior cerebral artery
olfactory nerves, olfactory bulb and tract, optic chiasm, optic nerve, optic tract
structures supplied by the posterior cerebral artery
oculomotor nucleus, edinger-westphal, trochlear nucleus
structures supplied by AICA
motor nucleus, chief sensory nucleus, trigeminal nerve, abducens nerve, facial nucleus, superior salivatory nucleus, facial nerve
structures supplied by pica
cochlear nuclei, vestibular nuclei, all components of glossopharyngeal, nucleus ambiguous, vagus nerve
structures supplied by anterior spinal artery
accessory nucleus, hypoglossal nucleus
syndrome caused by lesion to the ventral pons; syndrome caused by lesion to the middle pons
Raymond’s Syndrome
Millard-Gubler Syndrome
syndrome caused by lesion to the dorsal pons; what structures are involved?
Foville’s syndrome: nuclei VI (MLF) and VII, CN VII
what cranial nerve is involved in a ventral pons lesion?
CN VI
what cranial nerve is involved in a middle pons lesion?
CN VII
what lesion/name is given to the locked in syndrome? symptoms?
dorsal pons lesion (Foville’s syndrome); ipsilateral facial paralysis, loss of conjugate movement on contralateral medial rectus
damage to the LCST and CN III in the midbrain causes what syndrome? symptoms?
Weber’s syndrome; contralateral hemiparesis, ipsilateral ocular paresis
where is the lesion in Parinaud’s syndrome? what are the signs?
superior colliculi (midbrain) lesion; paralysis of upward gaze – like paranoid, can’t look upward.
the central core of the brainstem, with single neurons of mixed function with multiple inputs and outputs
reticular formation
functions of reticular formation
pain suppression, autonomic reflexes, descending sympathetics, arousal consciousness, posture
where is the pain suppression system of RF located?
nucleus raphe magnus in pons
where is the autonomic reflexes of RF located?
respiratory center-medulla, pons
cardiovascular centers- medulla
the descending sympathetics of RF descend from..
hypothalamus
part of the RF that does arousal and consciousness
ascending reticular activating system (ARAS)
part of RF that does posture
reticulospinal tracts
the 3 longitudinal zones of the reticular formation, and what is in each of them
median zone: raphe nuclei
medial zone: ascending and descending projections, POSTURE TRACTS, medullary and pontine reticulospinal tracts
lateral zone: CN reflexes and visceral functions
function, location in the brainstem, nuclei involved with norepinephrine (NE)
attention; locus ceruleus in lateral RF, solitary nucleus, dorsal motor nucleus of X
function, locations, what happens when its deficient -dopamine (DA)
initiation of movement, motivation, cognition; substantia nigra axons to striatum, ventral tegmental area axons to limbic system; schizophrenic hallucinations, dreams, can cause seizures, parkinson’s
function, location of serotonin (5-HT)
arousal, pain control; raphe nuclei
functions, locations of acetylcholine
muscarinic receptors in CNS, sleep/wake cycle; reticular formation to thalamus, basal forebrain (nucleus basalis of meynert to cortex, amygdala, hippocampus), striatum interneurons
function of antipsychotics
block dopamine receptors in ventral tegmental area (VTA)
function of antidepressants
norepinephrine (lateral column) and serotonin (raphe) receptor alterations, increase levels of dopamine and norepinephrine
replacement therapy for alzheimer’s and Parkinson’s patients
ACh (nucleus basalis) given to Alz px; dopamine (substantia nigra) given to Parkinson’s px
