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Neuroanatomy > Unit 8 > Flashcards

Unit 8 Flashcards

1
Q

Midbrain has which colliculus?

A

superior and inferior colliculus

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2
Q

basic functions of brainstem

A

cranial nerves
pathway for ascending/descending tracts
integration
esp. reticular formation

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3
Q

Tectum, roof, is really only found in the midbrain. T or F

A

T

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4
Q

tegmentum can be found in what aspects of the brainstem?

A

mid brain/pons/medula
But i starts anteriorly and moves posteriorly

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5
Q

alar plate (sensory)+ basal plate (motor) and now in the brainstem the motor nuclei are more ________ and the lateral is more _________

A

motor medial/sensory lateraly

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6
Q

Contents of rostral midbrain?

A

Superior colliculus
Oculomotor nucleus
Edinger-Westphal nucleus
Substantia nigra
Red nucleus

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7
Q

How I remember midbrain contents?

A

EORSS

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8
Q

Oculomotor Nucleus

A

in rostral midbrain
Function
ipsilateral control of eyelid & 4 extraocular muscles
superior rectus
medial rectus
inferior rectus
inferior oblique
via CN III

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9
Q

Oculomotor NucleusLesion

A

Impaired eye movement
lateral strabismus
diplopia
double vision
vertical eye movements impaired
Ptosis
drooping eyelid

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10
Q

Edinger-Westphal Nucleus

A

in rostral midbrain
Function
pupil constriction
focus
carried on CN III
oculomotor n.
Lesion
mydriasis
dilated pupil
fails pupillary light reflex test
cannot focus near

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11
Q

Substantia Nigra

A

in rostral midbrain
Function
part of basal ganglia
dopamine production
pars compacta
Lesion
Parkinson’s Disease

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12
Q

Red Nucleus

A

in rostral midbrain
almost to thalamus
Function
part of cortical/cerebellar motor circuit
Lesion
rostral to red nucleus
=decorticate rigidity
caudal to red nucleus
=decerebrate rigidity
may also exhibit cerebellar signs (e.g., ataxia)

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13
Q

Lesions of Upper Motor Pathways
Damage rostral to midbrain
rostral to red nucleus

A

= decorticate posture
“toward the cord”
arms, hands, & fingers flexed
legs extended & internally rotated

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14
Q

Lesions of Upper Motor Pathways
Damage caudal to midbrain
caudal to red nucleus

A

decerebrate posture
“lots of E’s”
arms extended
esp elbows
arms & legs extended and internally rotated

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15
Q

Caudal Midbrain contents

A

both posterior
inferior colliculus
Trochlear nucleus

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16
Q

Trochlear Nucleus

A

in caudal midbrain
near midline
Function
control of contralateral superior oblique m.
via CN IV
only CN to emerge dorsally
Lesion
diplopia while looking down and lateral
e.g., descending stairs, reading
less noticeable than other ocular muscle deficiencies

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17
Q

Pons Content

A

Mescencephalic nucleus of V
Trigeminal motor nucleus
Trigeminal main sensory nucleus

Abducens nucleus
Facial motor nucleus
Cochlear nucleus
Vestibular nuclei (continue into medulla)

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18
Q

Trigeminal Motor Nucleus

A

in mid-pons
Function
motor neurons for muscles of mastication
masseter, temporalis, pterygoids
Lesion
unilateral have no symptoms
due to bilateral innervation
bilateral lesions often result in poor chewing

19
Q

Trigeminal Main Sensory Nucleus

A

aka – principal sensory nucleus of V
in mid-pons
Function
conscious sensation of face & head
synapses here (midpons), decussates immediately, & then joins medial lemniscus
Lesion
ipsilateral loss of touch sensation in face/head

20
Q

Abducens Nucleus (VI)

A

in caudal pons
~close to midline
Function
control of ipsilateral lateral rectus m.
Lesion
medial strabismus

21
Q

Abducens Nucleus Lesion

A

Coordinates with contralateral CN III (medial rectus) via MLF pathway
L abducens damaged
Looking straight ahead: L eye medial strabismus
Looking towards the L :strabismus worse

22
Q

Facial Motor Nucleus (VII)

A

in caudal pons
~close to midline
Function
control of facial muscles
bilateral to upper face
unilateral to lower face (ipsilateral)
Lesion
hemiplegia of ipsilateral face
more pronounced symptoms in lower face muscles

23
Q

Facial Nerve Fun points

A

Facial nerve courses posteriormedially
around abducens nucleus
Forms big “U”
genu of the facial nerve
exits at pons/medulla junction

25
Cochlear Nucleus
in caudal pons extreme lateral position Function receive auditory input from cochlear division of CN VIII Lesion loss of specific frequencies in ipsilateral ear
26
Auditory Pathway Fun facts
Some fibers from cochlear nucleus decussate & some do not Ascend in lateral lemniscus to inferior colliculus Bilateral input to thalamus/auditory cortex
27
Vestibular Nuclei
Spread out from mid-pons to mid-medulla 4 separate nuclei Function receive sensory (vestibular) information about head position & movement from vestibular portion of VIII VOR equilibrium outputs to ocular muscle nuclei & vestibulospinal tracts Lesion vertigo, nystagmus
28
Head rotation to the L results in coordinated contraction of which muscles and which nerves ? VOR example
left medial rectus via CN III right lateral rectus via CN VI
29
Rostral medulla contents
hypoglossal nucleus dorsal motor nucleus of the vagus nucleus of solitary tract cuneate nucleus (UE) lateral cuneate nucleus nucleus ambiguus spinothalamic tract spinotrigeminal tract spinotrigeminal nucleu
30
Rostral medulla nuclei only way for me to remember
HAVSS Hypoglossal Ambiguus Vagus (dorsal motor nucleus of the vagus) Spinotrigeminal nucleus Solitary tract (nucleus of)
31
Nucleus of the Solitary Tract
in caudal pons to medulla Function visceral sensory from face & body CNs VII, IX, & X taste BP (carotid sinus) lung or stomach distension Lesion loss of taste increased heart rate
32
Dorsal Motor Nucleus of the Vagus
in medulla Function visceral motor (parasympathetic output) to thorax & abdomen preganglionic neurons of CN X Lesion GI & cardiopulmonary changes
33
Nucleus Ambiguus
Dual function branchial motor CNs IX & X pharyngeal muscles lesion = dysphagia trouble swallowing dysphonia trouble speaking visceral motor (parasympathetic) CN X e.g., cardioinhibitory baroreflex ↓ HR when BP↑ lesion = ?
34
Hypoglossal Nucleus (XII)
in medulla Function ipsilateral tongue muscles Lesion ipsilateral tongue weakness protrudes to weak side
35
Spinal Trigeminal Nucleus (and tract)
Pain/temperature fibers from face enter on CN V at mid-pons travel caudally on spinal trigeminal tract somatotopic synapse in spinal trigeminal nucleus throughout medulla, but esp. caudal region down to ~ C3 (thus the name) fibers from Spinal trigeminal nucleus decussate & join spinothalamic tract
36
Accessory Nucleus (XI)
in ventral horn of upper cervical spinal cord rootlets of CN XI ascend alongside cord & exit the jugular foramen Function motor control Lesion ipsilateral weakness of SCM & trapezius
37
Reticular System
“net-like” Diffuse/distributed system of nuclei throughout the brainstem median, medial & lateral regions raphe, magnocellular, parvocellular Two functional components Ascending reticular activating system (ARAS) modify cerebral cortex alertness, arousal, sleep/wake Descending reticular formation somatic motor autonomic output pain modulation (analgesia)
38
ARAS
Respond to almost all sensory information ascending through the brainstem Primarily located in midbrain Widespread projections esp to intralaminar thalamic nuclei & forebrain Lesion coma
39
Descending Reticular System
Skeletal motor posture, balance, vestibular reflexes via reticulospinal tracts pontine/medial inhibits flexion e.g., only noxious stimuli cause flexor reflex medullary/lateral inhibits extension
40
Descending Reticular System
Autonomic motor ‘vegetative’ functions Inputs from hypothalamus & visceral sensory info Regulation of ventilation e.g., dorsal/ventral respiratory groups cardiovascular various cardio-inhibitory & -acceleratory areas swallowing sneezing urination/defecation
41
Descending Reticular System Pain
Analgesic/pain modification decreases pain transmission via PAG periaqueductal gray site of action of many painkillers esp opiates
42
Ascending Tracts of the Brainstem
Medial lemniscus conscious touch/proprio Anterolateral system spinothalamic tract pain/temp Medial longitudinal fasciculus (MLF) ascending = eye movement descending = medial vestibulospinal tract Lateral lemniscus auditory info
43
Descending Tracts of the Brainstem
Corticospinal tracts Corticobulbar tracts Corticopontine tracts Spinal trigeminal tract Descending sympathetic tracts Horner syndrome

Neuroanatomy (5 decks)

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