Neuroanatomy Flashcards
Name the vessels that make up the circle of Willis.
Anterior cerebral artery, anterior communicating artery, basilar artery, posterior cerebral artery, posterior communicating artery, and the medial cerebral artery.
Where do the two vertebral arteries join together to make the basilar artery?
What vessels does the basilar artery split into?
At the junction of the medulla and pons.
The posterior cerebral arteries.
Identify the components of the hippocampal portion (also known as medial lambic circuit) of the Papez circuit.
What is the significance of the Papez circuit?
Hippocampus—>Mammilary Bodies (via fornix) —> Anterior Thalamus (via mammilothalamic tract) —> Cingulate Gyrus —> Hippocampus
Effort to explain how the hypothalamus and cortex coordinate cognition and emotions.
Identify the components of the lateral limb if circuit (includes amygdala).
Amygdala —> dorsomedial nucleus of thalamus —> orbitofrontal cortex —> uncinate fasciculus —> Amygdala
What is the major pathway that connects Wernicke’s area with Broca’s area?
Name and describe the form of aphasia that occurs if this pathway is disrupted.
Arcuate fasciculus.
Conduction aphasia. Characterized by a disproportionate deficit in repetition with relative sparing in comprehension and fluency. Phonemic paraphasias occur.
What connects the lateral ventricles with the third ventricle? The third ventricle with the fourth?
Interventricular foramen of Monro.
Cerebral aqueduct. This is the point that is most prone to blockages. It is the narrowest point in ventricular system.
What is the basal ganglia comprised of (3 nuclei)?
Lentiform nucleus (putamen and globus pallidus)
Caudate nucleus
Amygdala
Name the primary superficial cerebral veins.
Superior anastomotic vein of Trolord, Superior sagittal sinus, Inferior anastomotic vein of Labbe, Transverse Sinsus, Sigmoid Sinus
What is the most influential contemporary model of intelligence? What does it posit?
Catell-Horn-Carroll (CHC) model from 1993.
Derived by factor analysis. Posits multiple distinct intelligences. 8 broad forms and more discrete abilities. Has influenced the Stanford-Binet and W-J.
What is the general psychometric standard for identifying someone as intellectual disabled?
IQ is about 2 or more SD below pop norms.
In what population(s) are savant skills usually observed?
What kinds of skills are more commonly observed?
Not common. Remarkable skill in a narrow area is most often observed in individuals with intellectual disability or autism spectrum disorder. Noting savant-like qualities should bring up concerns for neurodevelopmental disorders or past CNS injury.
Most common = superior memory, calculation, calendar knowledge, artistic, or language abilities.
Describe Posner and Petersen’s (1990) neurobiological model of attention.
Two Networks: Posterior and Anterior.
Posterior = orienting and shifting attention.
Anterior = Detection subsystem. Detecting stimuli from sensory events or from memory.
Work in conjunction with alerting network (ascending reticular activating system), which influences arousal.
What attentional tasks does the prefrontal cortex perform?
Response selection, control, sustained attention, focus, switching, searching, and alternating attention.
What kind of deficit might we hypothesize from orbitofrontal damange?
Disinhibition.
What kind of clinical presentation might we expect for someone with damage to the dorsolateral frontal cortex?
Reduced initiation (abulia).
Damage to the superior colliculus would affect what skill(s)?
Shifting attention & eye movements.
The lateral pulvinar is involved in what attentional task(s)?
Extracting information from target location. Filtering distractors.
What form of attentional disorder is produced when there is damage to the parietal cortex?
hemispatial neglect
Is it possible to develop right-sided neglect?
Yes, with damage to left parietal region. Left-sided neglect is more commonly observed following damage to the right hemisphere.
What are the most common cognitive deficits after mod/severe TBI?
Reduced arousal, reduced attentional capacity, distractibility, executive dysfunction, slowed processing speed.
What are the four components of language competence?
Phonology, Syntax, Semantics, Pragmatics
You are seeing a patient who was referred due to concern with aphasia and have no other clinical history. What aspects of language should you assess to perform an in-depth assessment of this cognitive domain?
Spontaneous speech, (fluent, non-fluent, rate, prosody, content).
Comprehension of spoken and written language (syntactic dysfunction suggestive of anterior speech areas, posterior language produces disturbed comprehension of the sequencing of meaningful word sounds used to convey meaning).
Repetition. Intact ability suggests that the perisylvian language centers are intact.
Naming
Reading. Usually associated with impaired verbal skills, but if alexia is observed in isolation then it can help with localization of dysfunction.
Writing.
A patient presents with nonfluent aphasia. What area of the cortex would you suspect has been affected?
Anterior language centers.
Posterior is usually associated with fluent aphasia.
You are seeing a patient for hospital follow up and happen to know that they had a stroke that heavily damaged the structures in the perisylvian area (areas around the sylvian fissure AKA lateral sulcus). What symptom would you anticipate as part of their presentation?
Impaired repetition.
What might suggest a more favorable recovery following a stroke to Broca’s area?
A more discrete lesion that does not extend into the subcortical tissue and/or if there is no associated right hemiparesis.
What are the characteristics of transcortical motor aphasa?
What area of the cortex is associated with this form of aphasia?
(Near) normal repetition abilities, but otherwise resembling Broca’s aphasia. Comprehension is intact, but verbal output is nonfluent.
Anterior to Broca’s area, often in the SMA.
A patient presents with impaired comprehension and intact repetition. They have some echolalia. The are fluent, but are unable to make meaningful statements What might you suspect?
Transcortical sensory aphasia from damage to the junction of the parietal, temporal, and occipital cortex. Damage often around the angular gyrus. Wernicke’s area is spared, hence the intact repetition.
Curiously, the patient may still not understand what they are repeating.
A patient presents with loss of auditory comprehension of speech, but are able to speak, read, and write. Repetition is impaired. Their condition is rare. What is it?
Pure word deafness. Involves a unique set of dmanage to both temporal lobes with destruction of Heschl’s gyrus on the left and the white matter tract connecting it to the auditory association area on the right.
Damage to which of the following is most likely to create dense amnesia:
a) hippocampus
b) anterior thalamus and cingulate gyrus
c) orbitofrontal area and mammillary bodies
d) amygdala
c) is the correct response. This is the only choice that involves areas of both the medial and lateral circuits. Damage to both circuits is the most likely to produce dense amnestic conditions.
Damage restricted to the arcuate fasiculus produces which disproportionate deficits?
Restricted damage to the arcuate fasiculus produces a disproportionate deficit in repetition, with relative sparing of comprehension and fluency.
______ is one key inhibitory neurotransmitter, whereas ______ is the most abundant excitatory neurotransmitter in the brain.
GABA (gamma-aminobutyric acid), Glutamate.
This dopamine pathway is implicated in Parknison’s disease.
Mesostriatal; substantia nigra pars compacta (SNpc)
A patient is being referred who had experienced a ruptured ACoA aneurysm. The referral includes concern with “memory problems.” What may be the “frontal amnestic” characteristics that you might expect to see?
Ruptured ACoA often results in damage to the basal forebrain, striatal, and frontal systems. This form of frontal amnesia often includes confabulation, attentional problems, disorientation, some apathy/reduced insight, and variable retrograde amnesia.
Alzheimer’s disease affects memory _____, whereas patient’s with dementia impacting frontal-subcortical systems typically display _____ difficulties.
encoding; retrieval difficulties and are thus helped with recognition cueing.
What personality/emotional change may you suspect to see in a patient being referred who experienced a brain injury involving the left frontal lobe?
Depression and negativism. The left frontal lobe is thought to underlie positive emotional valence so that, with injury, depression results.
Wernicke-Korsakoff’s syndrome effects which brain system and structures?
In addition to both anterograde and retrograde amnesia, confabulation, and poor insight, what additional associated symptoms might you also see?
Diencephalon system - anterior and dorsomedial nuclei of the thalamus, fornix, mammillary bodies.
You might also suspect to see gait ataxia, oculomotor palsy, and encephalopathy.
What area of the internal capsule is occupied by afferent fibers from the precentral gyrus (primary motor cortex)?
The middle third of the posterior section.
In the assessment of ideational and ideomotor apraxia, what is the difference between transitive and intransitive movements?
Transitive = those done a goal-directed movement with an object.
Intransitive = those done without specific goal and without use of an object, like hand gestures.
The head and tail of the caudate lie ______________ to the white matter of the internal capsule and corona radiata.
Medial
What white matter structure is lateral to the lenticular nucleus?
External capsule.
What two structures make up the lenticular nucleus?
The striatum?
Globus pallidus and putamen. The GP is more medial.
Caudate, putamen and nucleus accumbens.
The claustrum is a thin strip of grey matter located between two white matter structures (per horizontal section). What are they?
External capsule and extreme capsule.
The thalamus has no distinct inferior border. It merges with the superior portion of the ________________.
Midbrain.
Name the components of the brainstem from most inferior to most superior.
Medulla, pons, midbrain.
Sensory fibers pass from the thalamus to the cortex via the ____________________.
Internal capsule.
Corticospinal fibers travel through the internal capsule but bypass the thalamus. Instead, they descend by weaving through the basal nucleus and entering the ipsilateral midbrain. They generally decussate at the level of the medulla.
Three main tracts start in the cortex and travel down into or through the brainstem. What are they?
Corticopontine
Frontopontine
Corticospinal
What does CN III do? What sign(s) on neuro exam would suggest CN III dysfunction?
The oculomotor nerve projects to the iris and five of the extraocular muscles.
Functions include moving the eyes in upwards, downwards, and medial directions as well as pupillary dysfunction. A blown pupil is observed when herniation compresses CN III. Pupillary constriction can suggest pontine damage or intoxication.
A lesion on what area of the visual pathways are likely to produce a loss of a visual hemifield on the same side in both eyes?
Homonymous hemianopsia is produced by a lesion in the lateral geniculate nucleus, optic radiations, or contralateral occipital lobe.
A lesion in what area of the visual pathways are likely to produce a loss of of a visual field quadrant?
Homonymous quardrantanopsia suggests disruption of axons in Meyer’s loop in the posterior temporal lobe opposite the field deficit.
Describe the visual pathway?
LGN. Projections from the retina go back to the optic chiasm (medial portion of retina remains ipsilateral, lateral portion of retina crosses) and on to the pulvinar, LGN, and into Meyer’s loops before ending up in the primary visual cortex.
Which part of the retina crosses to the contralateral side?
The lateral portion. The medial portion remains on the ipsilateral side. This arrangement results in contralateral representation of the visual fields in the occipital lobe.
The superior and inferior colliculi are located on ________.
The posterior surface of the midbrain. The superior colliculus is part of the visual pathway.
Name the tracts that project through the basis pedenculi of the brainstorm and order them from most medial to most lateral.
Starting with most medial, frontopontine, corticospinal, and corticopontine.
The frontopontine and corticicopontine tracts terminate in the pons while the corticospinal tract goes on to the medulla and beyond.
What percentage of corticospinal fibers cross the midline in the lower medulla?
70-90%
The fibers that cross the midline become the lateral corticospinal tract in the cord.
The 10-30% of fibers that don’t cross become the anterior corticospinal tract.
Where do most of the extrapyramidal fibers originate from?
The basal nuclei
The more inferior portions of the precentral gyrus are represented in the ___________ portion of the internal capsule’s posterior limb.
The more superior portions of the precentral gyrus are represented in the ___________ portion.
Anterior, posterior. Going from anterior to posterior, think face, hand, leg.
What neurological features might suggest a stroke in the internal capsule
Impaired voluntary movement and preserved limb reflexes.
The more superior portions of the precentral gyrus are represented in the __________ portion of the basis pedunculi while the more inferior portions of the precentral gyrus are represented in the ________ portion of the basis pedunculi.
Medial, lateral. Going from medical to lateral, think face, hand, leg.
Describe the basic pattern of corticostriatal inputs and outputs.
Cerebral cortex (excitatory) to caudate and putamen (inhibitory) to globus pallidus (inhibitory) to thalamus
What are the two primary pathways from the globus pallidus to the thalamus?
Lenticular fasciculus and ands lenticularis.
The lenticular fasciculus and the ands lenticularis join together to form the ___________ ____________.
Thalamus fasciculus. This projects to the ventral anterior nucleus of the thalamus.
What are the four primary inputs to the extrapyramidal pathways?
Superior colliculus
Red nucleus
Reticular formation
Vestibular nuclei
These project to the spinal cord,as does the pyramidal tract.
The vestibulospinal tract is split into medial and lateral pathways. Describe their paths.
The medial vestibulospinal tract arises from the medial and inferior vestibular nuclei and descends bilaterally through the medial longitudinal fasciculus.
The lateral vestibular nucleus gives rise to the lateral vestibular tract which descends ipsilaterally in the ventral funiculi of the spinal cord.
What functions do the medial and lateral vestibulospinal tracts serve?
Medial is involved in adjusting head position in response to changes in posture.
Lateral is involved in controlling extensor muscles of the trunk and proximal limbs.
The reticulospinal tract is involved in ___________.
Activation and inhibition of the extensor spinal muscle reflexes.
The medial tract activated them and the lateral tract inhibits them.
The red nucleus receives projections from what areas?
How does the rubrospinal tract descend to augment the function of the corticospinal tract?
Motor and premotor areas (Broadman 4 & 6).
Goes from red nucleus, crosses midline, and descends in the brainstorm.
Which blood vessel gives rise to the lenticulostriate arteries?
Based on their name, what do they supply with blood?
MCA
The lenticular nucleus includes the putamen and globus pallidus. The striatum consists of the lenticular and caudate nuclei.
The ACA contributes blood to the basal nuclei via what artery?
The middle striate artery. It supplies blood to the head of the caudate and the putamen.
Identify the elements of the direct pathway from the basal nuclei to the thalamus and cortex.
The cortex excites the neostriatum (along with excitatory input from SN) which inhibits the globus pallidus which inhibits the thalamus.
Thus more cortical input inhibits the GP which allows the thalamus to signal to the cortex. This facilitates movement.
The anterior lobe of the cerebellum receives inputs from______.
Spinocerebellar tracts and golgi tendon organs.
The inputs help the cerebellum function to maintain synergy in trunk muscles for walking and standing.
The posterior lobe of the cerebellum receives input from _______.
The motor areas of the cerebral cortex via pontine nuclei.
The posterior lobe is primarily concerned with coordinating of voluntary activity.
