Neural Basis M12 and 13 Exam

main supply for verebrovascular system

Aorta gives rise to the vertebral arteries and common carotid arteries

• Two divisions of the cerebrovascular system

– Anterior branch: carotid artery

– Posterior branch: vertebral branch

carotid division

Common carotid artery bifurcates

– Gives rise to internal and external carotid artery

• Internal carotid artery gives rise to anterior and middle cerebral arteries

circle of willis

“Backup system” for vascular supply

• Safeguard of the vascular supply

• If something occludes one portion, possibility of getting blood supply through other system

• Series of anastomoses that provide redundancy for a constant blood supply

• Completely encircle optic chiasm

• Helps equalize locally high or low blood pressure

anterior cerebral artery

Course:

– Arises from internal carotid artery

– Courses over superior surface of corpus callosum in medial longitudinal fissure

– Left and right anterior cerebral arteries are connected by anterior communicating artery

• Serves medial surface of frontal, parietal lobes

• Serves

– Corpus callosum

– Leg area of frontal and parietal lobes

– Cingulate gyrus (emotional regulation)

– Anterior frontal lobes (including infraorbital)

– Head of caudate nucleus

medial frontal lesion

occlusion of anterior cerebral artery cause

Contralateral lower extremity weakness – paraplegia if bilateral

medial parietal lesion

occlusion of anterior cerebral artery cause

foot and leg sensory deficit

– contralateral grasp, grope, sucking reflex

– Intraparietal sulcus (variable with middle cerebral artery)

cingulate gyrus lesion

occlusion of anterior cerebral artery cause

deficit in emotional regulation

corpus callosum

occlusion of anterior cerebral artery cause

deficit in info integration between hemispheres

head of caudate lesion

motor disturbance (initiation, termination, hyperkinesia, hypokinesia)

middle cerebral artery

serves:

Lateral cortex and subsurface white matter: all language territory

• Insular cortex

• Anterior Internal capsule and genu

• Putamen and part of globus pallidus

insula

lesion of middle cerebral artery cause

verbal apraxia, self-awareness deficit

wernicke’s area

lesion of middle cerebral artery cause

receptive language deficit

broca’s area

lesion of middle cerebral artery cause

expressive language deficit

angular gyrus

lesion of middle cerebral artery cause

reading deficit

precentral gyrus

lesion of middle cerebral artery cause

paralysis or paresis, dysarthria

postcenral gyrus

lesion of middle cerebral artery cause

sensory deficit

middle temporal gyrus

lesion of middle cerebral artery cause

language and auditory processing deficit

inferior temporal gyrus

lesion of middle cerebral artery cause

visual integration deficit

anterior internal capsule and genu

lesion of middle cerebral artery cause

dysarthria secondary to cranial nerve innervation loss

anterior and lateral choroidal artery

serves parts of thalamus, posterior internal thalamus, posterior internal capsule, part of globus pallidus

vertebral division (vertebrobasilar)

serves anterior surface of medulla, pons, cerebellum

posterior cerebral artery

Inferior temporal lobe, including hippocampus and fusiform gyrus

– Thalamus

– Occipital lobe

– Midbrain

– Posterior internal capsule

• Hippocampus

• Thalamus (basilar and anterior choroidal artery)

posterior communicating artery

Sends arterioles to thalamus, posterior internal capsule, optic tract, cerebral peduncles, medial temporal lobe, thalamus, some of corpus striatum

ischemia

loss of blood flow to an area

or ischemic stroke

damage to midbrain nuclei

II ophthalmic: vision

– III oculomotor: eye movement

– IV trochlear: eye movement

damage to nuclei of pons

V trigeminal: masticator paralysis, loss of facial sensation – VI abducens: eye movement

– VII facial: facial nerves, taste, salivary glands

– VIII vestibulocochlear: hearing and balance

damage to nuclei of medullar

IX glossopharyngeal: swallowing, taste

– X vagus: laryngeal muscles, swallowing

– XI accessory: sternocleidomastoid

• XII hypoglossal: tongue paralysis

inferior temporal lobe of cortical posterior artery infarct

hippocampus: memory

fusiform gyrus: facial recognition

thalamus and globus pallidus and cortical posterior artery infarct

Via lateral and anterior choroidal arteries: lateral choroidal artery is from posterior cerebral artery

– Sensory and motor deficit, including muscle tone disturbance

brainstem posterior artery ischemia

Midbrain:

– red nucleus: extrapyramidal syndromes

– substantia nigra: Parkinsonism

– Superior cerebellar peduncle: motor planning dysfunction

– Cerebral peduncles: spastic paralysis, speech and other voluntary musculature

– reticular formation of BS: coma

– cranial nuclei for II and III: vision and oculomotor function

– II ophthalmic and auditory pathway function: superior and inferior colliculuS

specific posterior cerebral artery syndromes

red nucleus

cerebral peduncle

Cerebral Peduncle Syndrome from Posterior Cerebral Artery Infarct

Cerebral peduncle syndrome:

• Substantia nigra: Parkinsonism

• Corticospinal tract: spastic paralysis

• Corticonuclear (corticobulbar) fibers: facial and tongue paralysis

• III Oculomotor nerve: ocular paralysis

red nucleus syndrome from PCA lesion

Red nucleus syndrome (midbrain)

• Medial lemniscus: impairment of touch, position, vibration

– Medial lemniscus conveys body sense from gracile and cuneate nuclei (fasciculus gracilis and fasciculus cuneatus) to thalamus

• Red nucleus: hyperkinesia (chorea, athetosis)

• Substantia nigra: Parkinsonsism

• III oculomotor nerve: ocular paralysis, fixed pupil

specific pons syndromes

Syndrome of caudal basis pontis

• Caudal pontine tegmentum syndrome

• Oral pontine tegmentum syndrome

syndrome of caudal basis pontis

Medial lemniscus: impairment of touch, position, and vibration sense

• Lateral lemniscus: hearing loss

• Lateral spinothalamic tract: analgesia (reduced pain sensation) and thermanesthesia (reduced temperature sense)

• Pyramidal tract: spastic paralysis

• VI abducens: ocular movement paralysis

• VII facial nucleus: facial muscle paralysis

caudal pontine tegmentum syndrome

Caudal pontine tegmentum syndrome (area near 4th ventricle)

– Medial longitudinal fasciculus: gaze paresis and nystagmus

– VI abducens: eye movement paralysis

– VIII vestibular nuclei: nystagmus, vertigo

– V trigeminal nucleus: facial hypesthesia and analgeisa (reduced tactile sense and pain) and thermesthesia (thermal sense)

– VII facial: facial paralysis

– Tegmetum of pons: palatopharyngeal myoclonus

– Anterior spinocerebellar tract: asynergia (dysynchrony of movement) and hypotonia (low muscle tone)

– Lateral lemniscus: hearing loss

– Lateral spinothalamic tract: analgesia, thermanesthesia – Medial lemniscus: touch impairment, position sense, vibration

oral pontine tegmentum syndrome

Oral pontine tegmentum syndrome:

• Superior cerebellar peduncle: ataxia, intention tremor, adiodochokinesia, cerebellar dysarthria

• V trigeminal: facial sensation, masticator paralysis

• Central tegmental tract: palatopharyngeal –laryngeal myoclonus

• Tectospinal tract: absence of blinking reflex

• Lateral spinothalamic tract: analgesia, thermanesthesia • Lateral leminiscus: hearing loss

• Medial lemniscus: touch, vibration, position impairment, ataxia

• Corticonuclear tract: facial, tongue, laryngeal paralysis

specific medulla syndromes

Medial medullary syndrome

• Dorsolateral medullary syndrome (Wallenberg’s syndrome)

medial medullary syndrome

Medial medullary syndrome:

• XII Hypoglossal: flaccid tongue paralysis

• VII facial: contralateral flaccid hemiplegia with Babinski sign

• Medial lemniscus: contralateral hypoesthesia, impaired position sense

• Inferior olive: palatopharyngeal myoclonus

• Medial longitudinal fasciculus: nystagmus

dorsolateral medullary syndrome (wallenberg’s syndrome)

Dorsolateral medullary syndrome (Wallenberg’s syndrome) from inferior cerebellar or vertebral arteries

• V trigeminal motor nucleus: analgesia, thermanesthesia

• VII facial: ageusia (taste deficit)

• VIII vestibulocochlear nerve: Vertigo and nystagmus, hearing loss

• X vagus: tachycardia (racing heart), dyspnea (shortness of breath), palatal and vocal fold paralysis

• Anterior spinocerebellar tract: ataxia, hypotonia

• Lateral spinothalamic tract: analgesia, thermanesthesia

• Inferior cerebellar peduncle: ataxia and asynergia

• Reticular formation: Nausea, vomiting, hiccups (singultus

cerebellar artery ischemiaq

• Cerebellum:

– Motor coordination disturbance, terminal tremor

– Visual-motor integration deficit

pathway

motor cortex

internal capsule

brainstem decussation

spinal cord

synapse w/ LMN

muscle activation

lesions above level of decussation

contralateral deficits

spastic

strained- spasm, tight voice

lesions below level of decussation

ipsilateral deficit

flaccid

slurred, breathy, weak speech

gray matter

cell bodies

dorsal root ganglia

nuclei with afferent spinal nerves

motor nuclei

ventral side of spinal cord

ventral horns

efferent spinal nerves

dermatome

different spinal nerves

corticospinal tract

tract associated w/ activation of spinal nerves

coricobulbar tract

associated w/ activation of cranial nerves