Neuroanatomy-ENC Flashcards by Torin Karsonovich

Into what 3 segments are the medulla, pons and midbrain further divided?

Tectum (“roof”, dorsal aspect)
Tegmentum (ventral aspect)
Basis (most ventral aspect of tegmentum)

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Which artery or arteries supply the medulla?

Branches of the vertebral arteries, PICA, anterior and posterior spinal arteries

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Which ascending pathways are present in the medulla?

Dorsal columnar (medial lemniscal), spinothalamic, spinoreticular, and spinocerebellar

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Which descending pathways are present in the medulla and what functions do they mediate?

Corticospinal tract (motor)
Descending spinal tract of CN V
Medial longitudinal fasciculus (gaze and head movements.
Tectospinal tract (neck and trunk movements in response to visual stimuli)

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What fibers do the inferior cerebellar peduncles contain?

Fibers efferent from spinal cord and medulla to cerebellum, and crossed olivocerebellar fibers

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Which CN nuclei are housed within the medulla, and what functions do they mediate?

Hypoglossal nucleus (motor to tongue), dorsal motor nucleus of X (parasympathetic innervation of viscera), solitary tract and nucleus (taste and visceral sensory to VPM of thalamus.

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How is the homunculus organized in the medullary medial leminscus?

Cervical sensory info is dorsal/posterior to sacral info.

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Occlusion of what artery or arteries leads to medial medullary syndrome?

Vertebral branches or the anterior spinal artery

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What are the symptoms of medial medullary syndrome?

Contralateral hemiparesis (ipsilateral pyramid), contralateral sensory deficits (medial lemniscus), ipsilateral paralysis and atrophy of tongue muscles (hypoglossal nerve or nucleus)

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Occlusion of what artery leads to lateral medullary (Wallenberg’s) syndrome?

Vertebral branches (most commonly) or PICA.

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What are the symptoms of Wallenberg’s syndrome?

Loss of pain and temperature sensation over contralateral body (spinothalamic tract).
Loss of pain and temp over ipsilateral face (spinal trigeminal tract).
Hoarseness and dysphagia (nucleus ambiguous)
Ipsilateral Horner’s (descending sympathetics)
Possible vertigo, abnormal eye movements, and ipsilateral cerebellar deficits (inferior cerebellar peduncle and adjacent vestibular nuclei).

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Occlusion of what artery or arteries lead to Weber’s syndrome?

Branch of the PCA.

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What gross structure is damaged in Weber’s syndrome?

Cerebral peduncle

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What are the symptoms of Weber’s syndrome?

Contralateral spastic paresis (corticospinal fibers)

2. Ipsilateral ptosis, pupillary dilation, and lateral strabismus (occulomotor nerve)

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Which artery or arteries supply the pons?

Basilar artery and its branches (paramedian and circumferential branches), with some contribution from AICA and SCA.

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Which structures are contained within the basis pontis?

Corticospinal fibers, pontine nuclei, pontocerebellar fibers

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Which neurotransmitter is contained within the raphe nucleus?

Serotonin

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How is the homunculus oriented in the pontine medial lemniscus?

The feet are represented laterally, with the cervical sensory input represented medially.

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Which artery or arteries supply the midbrain?

PCAs with some contribution from the basilar artery branches and the SCAs

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Which 3 important structures are contained within the base of the midbrain?

Crus cerebri (includes corticospinal, corticobulbar, and corticopontine fibers), substantia nigra and cerebral peduncle

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To what structure does the substantia nigra send efferent dopaminergic fibers?

Striatum

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What fibers are contained within the cerebral peduncel?

Descending corticospinal and corticopontine fibers

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Which neurotransmitter is contained within the locus ceruleus?

Norepinephrine

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Which fibers are contained within the superior cerebellar peduncle?

Efferent fibers from the cerebellum to the red nucleus and spinocerebellar tracts

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What are the names of the phylogenetic segments of the cerebellum and what are their roles?

1. Archicerebellum (contains flocculus and nodulus, plays a role in posture, balance and eye movements) 2. Paleocerebellum (lower limb movements and speech) 3. Neocerebellum (limb coordination)

What are the cerebellar glomeruli?

Multiple synaptic contacts between mossy fibers with Golgi and granule cells that occur in the granular layer

What are the 3 cytoarchitectural layers of the cerebellar cortex?

An outer molecular layer, a Purkinje cell layer, and an inner granule cell layer

Where do climbing fibers originate?

In the contralateral inferior olivary nucleus

Where do mossy fibers originate?

Deep cerebellar nuclei, vestibular nuclei, the spinal cord, and the cerebellar cortex

Which peduncle is primarily efferent?

Superior cerebellar peduncle

Which CN emerges near the superior cerebellar peduncle?

CN IV

Which peduncle contains only afferent input?

Middle peduncle

Which fibers travel through the inferior cerebellar peduncle?

Input: posterior spinocerebellar tract, cuneocerebellar tract, vestibulocerebellar tract, trigeminocerebellar tract, olivocerebellar tract. Output: fibers from deep cerebellar nuclei terminating in contralateral red nucleus or contralateral thalamic motor nuclei (ventral lateral and ventral anterior)

What are the alternate names for the cerebellar peduncles?

Superior is brachium conjunctivum Middle is the brachium pontis Inferior is the corpus restiform or restiform body

Damage to the midline cerebeullum causes what deficit?

Postural instability

Damage to the lateral cerebellum causes what deficit?

Limb ataxia

Damage to the flocculus causes what deficit?

Difficulty with eye movements (poor pursuit and voluntary eye movements)

The thalamus is divided into 3 major nuclear masses (anterior, medial, lateral) by what white matter bundle?

Internal medullary lamina

What structures are contained within the central portion of the hypothalamus?

Tuber cinerum and infundibulum

Which hypothalamic nuclei release peptide hormones from the posterior pituitary or neurohypophysis?

Supraoptic and paraventricular nuclei

Which two peptides are released from the posterior pituitary?

ADH (vasopressin) and oxytocin

From what structure does the subthalamic nucleus receive input?

Globus pallidus

To what structures do fibers from the subthalamic nucleus project?

Globus pallidus

Which midline structure is contained within the epithalamus?

Pineal gland

Which fissure/sulcus contains the primary visual cortex?

Calcarine fissure

Which sulcus forms the anterior boundary for the occipital lobe?

Occipitoparietal sulcus

With what gyrus is the lingual gyrus continuous anteriorly?

Parahippocampal gyrus

What structure marks the transition from lingual to parahippocampal gyri?

The isthmus of the cingulate gyrus

What are the six layers of the neocortex (from superior to deep)?

1. Molecular layer 2. External granular layer 3. External pyramidal layer 4. Internal granular layer 5. Internal pyramidal layer 6. Multiform layer

Which structure forms the primary output pathway for the hippocampus?

Fornix

From what area do the majority of hippocampal inputs arise?

Entorhinal cortex (which receives inputs from the olfactory cortex, cingulate gyrus, orbital cortex, amygdala, and other temporal lobe areas)

Which nuclei are referred to as the lentiform nucleus?

Putamen and globus pallidus

From where do the primary outputs from the basal ganglia arise?

The primary basal ganglia outputs arise in the globus pallidus and substantia nigra pars reticulata

What is the net effect of the substantia nigra pars compacta on the basal ganglia circuitry?

Increases in dopamine from the substantia nigra pars compacta lead to an excitatory influence on the direct pathway (D1) and inhibitory influence on the indirect pathway (D2) resulting in a net increase in excitation/activation of the thalamus and cerebral cortex (movement)

Describe the fiber bundles carrying inhibitory projections from the globus pallidus internus to the thalamus?

1. Lenticular fasciculus: projects directly through the internal capsule. 2. Ansa lenticularis: courses around the medial edge of the internal capsule. 3. The above two join fibers from the SNr prior to entering the thalamus and are collectively known as the thalamic fasciculus

What neuro deficit would you expect from damage to the subthalamic nucleus?

Contralateral hemiballismus (violent, wide amplitude flinging motions of the extremities)

What neuro deficit would you expect from damage to the striatum?

Contralateral chorea (brief, irregular, dance-like movements)

Which arteries supply the basal ganglia?

1. Substantia nigra and STN: supplied mainly by the penetrating branches of PCA and PCOM. 2. Striatum and globus pallidus: supplied mainly by penetrating branches of the MCA (lateral striate or lenticulostriate arteries)

Where does the ICA become intradural?

Transition from C5 to C6 at distal dural ring

Between which two cranial nerves does the ICA course (C7 segment)?

Optic nerve and oculomotor nerve

In what cistern does the basilar artery terminate into PCAs?

Interpeduncular cistern

At what embryological age do fetal carotid-vertebrobasilar anastomoses arise?

At the 4-5 mm embryo stage (30 days of life)

In what order do the fetal anastomoses typically regress?

1. Otic. 2. Hypoglossal. 3. Trigeminal. 4. Proatlantal intersegmental.

Where does the persistent trigeminal artery attach to the basilar?

Between AICA and SCA

Persistent fetal circulations confer an increased risk of what type of vascular pathology?

Aneurysms and AVMs

In which nuclei do the parasympathetic preganglionic fibers traveling with each cranial nerve originate?

III: Edinger-Westphal nucleus in the midbrain VII: superior salivatory nuclei in the pons IX: inferior salivatory nucleus X: dorsal motor nucleus in the medulla

Which vessels are contained within the ambient cistern?

Vein of Rosenthal, PCAs and SCAs

Which layer of dura continues past the foramen magnum to form the spinal dura?

Inner (meningeal) layer

Which nerve innervates the dura?

CN V

Which meningeal layer forms the filum terminale?

Pia

Which meninges are formed from ectoderm?

Pia and arachnoid

Which meninges are formed from mesoderm?

Dura

Lesion causing seesaw nystagmus?

Posterior diencephalon/pretectum (interstitial nucleus of Cajal), para/suprasellar lesions, lateral medulla

Lesion causing spasmus mutans nystagmus?

Seen in infants, etiology site unclear. Associated with triad of head nodding, nystagmus, head turning.

Lesion causing lid nystagmus?

Lateral medulla, cerebellum.

Lesion causing Brun's nystagmus?

Pontomedullary junction, vestibular pathways.

Lesion causing ocular bobbing?

Central pons

Lesion causing ocular myoclonus?

Ipsilateral inferior olive, red nucleus, contralateral dentate nucleus (Guillain-Mollaret triangle)

Lesion causing upbeat nystagmus?

Medulla, ventral tegmentum, cerebellar pathways (anterior vermis)

Lesion causing downbeat nystagmus?

Cervicomedullary junction (Chiari), cerebellum, nuclei prepositus hypoglossi, medial vestibular nuclei

Lesion causing ocular flutter?

Cerebellar pathways, brainstem

Lesion causing abducting nystagmus?

Pons (MLF)

Lesion causing convergence-retraction nystagmus?

Dorsal midbrain, pretectum (pineal tumors)

With what gyrus is the lingual gyrus continuous anteriorly?

Parahippocampal gyrus.

What neurological deficit would you expect from damage to the globus pallidus?

Athetosis (slow, writhing movements of the hands and feet)

What neurological deficit would you expect from damage to the substantia nigra?

Rigidity and tremor.

Where does the corticospinal tract originate?

Majority of fibers originate in the primary motor cortex.

In which tract do sensory afferents caudal to T6 ascend?

Fasciculus gracilis

In which tract do sensory afferents rostral to T6 ascend?

Fasciculus cuneatus

What NT is used by preganglionic neurons of both sympathetic and parasympathetic systems when synapsing on postganglionic fibers?

Acetylcholine

What NT is used by parasympathetic postganglionic neurons when synapsing on target organs or tissues?

Acetylcholine

What NT is used by sympathetic postganglionic neurons when synapsing on target organs or tissues?

Norepinephrine

What NT is used by postganglionic sympathetic fibers innervating sweat glands?

Acetylcholine

Are preganglionic fibers myelinated? Postganglionic fibers?

Preganglionic fibers are mostly small-diameter myelinated B fibers. Postganglionic fibers are unmyelinated C fibers.

In which nuclei do the parasympathetic preganglionic fibers traveling with each CN originate?

III: Edinger-Westphal nucleus in the midbrain. VII: Superior salivatory nuclei in the pons, IX: inferior salivatory nucleus. X: dorsal motor nucleus of CN X in the medulla.