Neuroanatomy Flashcards

1
Q

Frontal lobe cortices

A

(Anterior to posterior)
1. Prefrontal cortex
2. Frontal eye fields
3. Premotor cortex
4. Primary motor cortex

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2
Q

Prefrontal cortex subregions

A
  1. Dorsomedial – behavioral activation (bilateral damage: apathy/mutism)
  2. Dorsolateral – cold EF, can also see apathy (damage: dysexecutive syndrome), persistence, perseverative errors on WCST
  3. Ventromedial – Hot EF, risk and fear (regulates limbic activity) (damage: disordered reward/punishment processing)
  4. Orbitofrontal – Hot EF, (damage: disinhibition)

“Hot core” of prefrontal region (orbital frontal and ventral medial) everything else “cold”

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3
Q

Cranial nerve name mnemonic

A

On (olfactory - smell)
Old (optic - vision)
Olympus’ (oculomotor - eye movement)
Towering (trochlear - eye movement)
Top (trigeminal - face sensation)
A (abducens - eye movement)
Fiercely (facial - motor to face)
Villainous (vestibulocochlear - balance and hearing)
German (glossopharyngeal - swallowing and taste)
Viewed (vagus - parasympathetic)
Some (spinal accessory - shoulder shrugging)
Hops (hypoglossal - tongue movement)

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4
Q

Cranial nerve function mnemonic

A

Some - olfactory (sensory)
Say - optic (sensory)
Marry - oculomotor (motor)
Money - trochlear (motor)
But - trigeminal (both)
My - aducens (motor)
Brother - facial (both)
Says - vestibulocochlear (sensory)
Big - glossopharyngeal (both)
Brains - vagus (both)
Matter - accessory (motor)
More - hypoglossal (motor)

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5
Q

Describe corticospinal tract route

A

Begins in the primary motor cortex and projects downward through white matter and brainstem

85% of fibers cross over (“pyramidal decussation”) at junction between medulla and spinal cord to control movement opposite side of body

Lesions above decussation produce contralateral (opposite side) weakness

Lesions below decussation produce ipsilateral (same side) weakness

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6
Q

Two main sensory pathways

A

• Posterior column pathways – convey proprioception, vibration sense, and fine discriminative touch
o Enter spinal cord via dorsal roots and columns to dorsal column in medulla (ipsilateral)
o Cross over to the other side of medulla
o Continue to ascend on the contralateral side and synapse in the thalamus
o Neurons then project to the primary somatosensory cortex

• Anterolateral pathways – convey pain, temperature sense, and crude touch
o Enter spinal cord via dorsal roots and synapse in spinal cord gray matter and cross over to other side of spinal cord
o Ascend in the anterolateral white matter, which forms the spinothalamic tract
o Synapses in the thalamus
o Continues to the primary somatosensory cortex

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7
Q

Limbic system structures

A

hippocampal formation, amygdala, limbic lobe (parahippocampal area and cingulate cortex)

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8
Q

Limbic system damage

A

• Lesions in the limbic system can cause deficits in the consolidation of immediate recall into longer-term memories. Thus, patients with lesions in these areas may have no trouble recalling remote events but have difficulty forming new memories.
• In addition, limbic dysfunction can cause behavioral changes and may underlie a number of psychiatric disorders.

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9
Q

Limbic system seizures

A

Epileptic seizures most commonly arise from the limbic structures of the medial temporal lobe, resulting in seizures that may begin with emotions such as fear, memory distortions such as déjà vu, or olfactory hallucinations.

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10
Q

Gerstmann’s syndrome

A

Lesions in the inferior parietal lobule in the left hemisphere can produce a constellation of abnormalities:

  • difficulty with calculations
  • right–left confusion
  • inability to identify fingers by name (finger agnosia)
  • difficulties with written language.
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11
Q

Describe the three fossae (i.e., compartments of the cranial cavity)

A

• The anterior fossa on each side contains the frontal lobe.
• The middle fossa contains the temporal lobe.
• The posterior fossa contains the cerebellum and brainstem.

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12
Q

Location of ventricles

A

• There are two lateral ventricles (one inside each cerebral hemisphere)
o have extensions called horns that are named after the lobes or after the direction in which they extend
- frontal horn
- occipital horn
- temporal horn
• third ventricle located within the thalamus and hypothalamus
• fourth ventricle located within the pons, medulla, and cerebellum.

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13
Q

Intracranial mass lesions can cause neurologic symptoms and signs by the following mechanisms:

A
  1. Compression and destruction of adjacent regions of the brain
  2. A mass located within the cranial vault can raise the intracranial pressure
  3. Mass lesions can displace nervous system structures so severely that they are shifted from one compartment into another (i.e., herniation) such as a midline shift
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14
Q

Symptoms and signs of elevated intracranial pressure

A

• headache – usually worse in the morning
• altered mental status (irritability, reduced alertness)
• nausea and vomiting
• papilledema – engorgement of optic disc
• visual loss
• double vision (aka diplopia)
• Cushing’s triad – hypertension, bradycardia, irregular breathing

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15
Q

Describe three herniations

A

• Tentorial/uncal herniation – herniation of the medial temporal lobe, especially the uncus (medial lobe), that pressed on CN 3
o Clinical triad: “blown” pupil (generally dilated pupil is ipsilateral to lesions), hemiplegia (usually weaker side is contralateral to lesion if corticospinal tract is affected above pyramidal decussation in the medulla), and coma
• Central herniation – central downward placement of the brainstem
• Subfalcine herniation – results from shift of cingulate gyrus; no clear clinical signs

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16
Q

What is a herniation?

A

Occurs when mass effect (i.e., distortion of normal brain geometry due to a mass lesion) is severe enough to push intracranial structures from one compartment to another

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17
Q

Severe head trauma can cause permanent injury through:

A

• diffuse axonal shear injury, which causes wide- spread or patchy damage to the white matter and cranial nerves;
• petechial hemorrhages, or small spots of blood in the white matter;
• larger intracranial hemorrhages
• cerebral contusion (bruise on the brain)
• direct tissue injury by penetrating trauma such as gunshot wounds or open skull fracture.
• Cerebral edema (swelling) may occur as well, with or without other injuries, contributing to elevated intracranial pressure in head injury.

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18
Q

Four types of intracranial hemorrhage

A

• Epidural hematoma (EDH) – between dura and skull, usually caused by fracture of temporal bone
• Subdural hematoma (SDH) - between dura and arachnoid
• Subarachnoid hemorrhage (SAH) – in CSF-filled space between the arachnoid and the pia, which contains the major blood vessels of the brain
• Intracerebral or intraparenchymal hemorrhage (ICH) - Within the brain parenchyma in the cerebral hemispheres, brain- stem, cerebellum, or spinal cord.

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19
Q

Hydrocephalus is excess CSF in the intracranial cavity due to:

A

• excess CSF production – rare cause; seen only in certain tumors
• obstruction of flow at any point in the ventricles or subarachnoid space – common cause due to infection, inflammation, prior hemorrhage, etc.; caused by congenital malformation or obstruction by tumors and masses, most likely in the narrow points of the CSF flow path:
o foramen of Monro – channel between lateral ventricles and third ventricle
o cerebral/Sylvian aqueduct – channel between third ventricle and fourth ventricle
o fourth ventricle – located posterior to pons and upper medulla & anterior to cerebellum
• decrease in reabsorption via the arachnoid granulations – same cause of obstruction

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20
Q

Where is CSF produced and absorbed?

A

produced in the choroid plexus (within the lateral, third, and fourth ventricles)

reabsorbed in the arachnoid granulations

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21
Q

Describe the four types of hydrocephalus

A

• Communicating hydrocephalus is caused by impaired CSF reabsorption in the arachnoid granulations, obstruction of flow in the subarachnoid space, or (rarely) by excess CSF production.
• Noncommunicating hydrocephalus is caused by obstruction of flow within the ventricular system.
• Normal pressure hydrocephalus is characterized by chronically dilated ventricles, sometimes seen in elderly individuals, presenting with symptom triad: gait difficulties, urinary incontinence, and mental decline (wet, wobbly, wacky) - thought to be form of communicating hydrocephalus with impaired CSF reabsorption at arachnoid villi
• Hydrocephalus ex vacuo – excessive CSF in region where brain tissue was lost due to stroke, surgery, trauma, etc. brain loss -> increased CSF -> ventricular enlargement (but normal pressure)

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22
Q

What is Parinaud’s syndrome?

A

Where third ventricle pushes down into midbrain; result in limited vertical gaze, especially in the upward direction. Particularly in children with acute hydrocephalus, the ominous “setting sun” sign, consisting of bilateral deviation of the eyes downward and inward, may be seen. These abnormalities often reverse after treatment.

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23
Q

Primary CNS vs. metastatic tumors

A

Primary CNS tumors – arise from abnormal proliferation of nervous system cells
Metastatic tumors – arise from neoplasm (abnormal growth of cells) elsewhere in the body that spread to the brain

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24
Q

Tentorium

A

Dura fold that separates the occipital and temporal lobes from cerebellum

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25
Q

Supratentorial

A

Portion of intracranial cavity above the tentorium (e.g., cerebrum)

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26
Q

Infratentorial

A

Portion of intracranial cavity below the tentorium (e.g., cerebellum)

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27
Q

Meninges

A

Skull
(Epidural space)
Dura mater (DURAble)
Arachnoid mater (granulations for CSF reabsorption)
Subarachnoid space (blood vessels) (CSF filled)
Pia mater
(Brain)

“PAD”

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28
Q

CN 1

A

Olfactory
Fx: sensory (smell - the only uncrossed sense)
olfactory loss = anosmia; due to tumor or trauma to orbitofrontal region, viral infections
May result in CSF leakage into nasal cavity
Connects to: frontal lobe

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29
Q

CN 2

A

Optic
Fx: sensory (vision)
prechiasmic lesion: monocular (one-eye) blindness
postchiasmic lesion: “homonymous hemianopsia” = loss of 1/2 of contralateral visual field on same side of both eyes
Connects to: thalamus

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30
Q

CN 3

A

Ocuolomotor
Fx: motor (eye movement and pupil restriction)
Compression of CN 3 = fixed or dilated pupil (blown pupil)
Significant constriction (pinpoint pupil) can suggest pons involvement or drug overdose (morphine)
Connects to: midbrain

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31
Q

CN 4

A

Trochlear
Fx: motor (eyes looking down)
Damage from cerebellar tumors or shearing injury from head trauma
Connects to: midbrain

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32
Q

CN 5

A

Trigeminal
Fx: motor and sensory (sensory innervation to face muscles, controls mastication)
Connects to: pons

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33
Q

CN 6

A

Abducens
Fx: motor (outward gaze - damage from increased intracranial pressure)
Connects to: pons

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34
Q

CN 7

A

Facial
Fx: sensory and motor (controls muscles of facial expressions, taste, and tears/salvation)

Upper motor neuron involvement: facial drooping with forehead
Lower motor neuron involvement: asymmetry of spontaneous facial expressions

Connects to: pons

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35
Q

CN 8

A

Vestibulocochlear
Fx: sensory (vertigo w/ nystagmus (uncontrolled eye movements) suggests nerve involvement
Connects to: pons

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36
Q

CN 9

A

Glossopharyngeal
Fx: sensory and motor (touch, pain, and temperature)
gag reflex, same as CN 10
Connects to: medulla

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37
Q

CN 10

A

Vagus
Fx: (sensory and motor) gag reflex and swallowing
Connects to: medulla

Assess: say “Ah”

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38
Q

CN 11

A

Spinal accessory
Fx: motor (trapezius muscles/shrugging)
Dysfunction - asymmetrical shrug
Connects to: spinal cord

Sternocleidomastoid strength and trapezius muscle lift are innervated by the ipsilateral cranial nerve XI.

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39
Q

CN 12

A

Hypoglossal
Fx: motor (tongue muscles)
Lesions: tongue weakness, subtle dysarthria (tongue deviates towards side of lesion) - asked to repeat “Methodist Episcopal”
Connects to: medulla

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40
Q

CN originating sites

A

olfactory - frontal lobe
optic - thalamus
oculomotor - midbrain
trochlear - midbrain
trigeminal - pons
abducens - pons
facial - pons
vestibulocochlear - pons
glossopharyngeal - medulla
vagus - medulla
spinal accessory - spinal cord
hypoglossal - medulla

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41
Q

Upper vs lower motor neuron

A

Upper (regulates lower motor neuron):
neuron located within brain/brainstem
body of neuron located in primary motor cortex
axon travels down spinal cord and innervates motor neuron in ventral horn

Lesion (“UPper” “hyper”) - increased tone, muscle reflex, and muscle contraction (spasticity)
can lead to atrophy because of disuse of muscle (b/c limited control)

Babinski sign - toes point up and fan out = upper motor neuron dysfunction in adult

Lower (innervates muscle):
originate in spinal cord
innervates skeletal muscle for movement

Lesion (“hypo” “down”) - decreased muscle tone, muscle reflex, and flaccidity b/c lose inability to control muscle
involuntary muscle contraction

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42
Q

Homunculus of primary motor and sensory cortices

A

Upper extremity: (medial to lateral) - trunk, arm, hand, face

Lower extremity: in the inter hemispheric fissure
(superior to inferior) - leg, foot

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43
Q

Origination of CN

A

CN 1 - frontal lobe
CN 2 - thalamus
CN 3-4 - midbrain
CN 5-8 - pons
CN 9-10 and 12 - medulla
CN 11 - spinal cord

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44
Q

Reticular formation

A

Fx: consciousness and autonomic functions

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45
Q

Neurologic exam

A
  1. Consciousness (d/t damage of reticular formation, thalamus (unilateral damage = mild impairment), or cerebral hemispheres
  2. Orientation
  3. Memory (poor imm. memory = attention; poor recall = implicate limbic structures/medial temporal lobes)
  4. Langauge
  5. Gerstmann’s syndrome (acalculia, agraphia, R/L confusion, finger agnosia) - suggests left parietal lobe
  6. Apraxia - inability to follow motor commands not due to motor or language deficit
  7. Neglect - hemineglect most common in R parietal lobe lesion
  8. Olfaction - CN 1
  9. Vision and pupillary responses - CN 2 & 3
  10. Extraocular movement - CN 3, 4, & 6 (smooth pursuit, convergence, saccades, nystagmus)
  11. Motor exam - lower (damage = decreased tone/spasticity, hypoflexia) and upper (damage = increased tone/spasticity, hyperflexia) motor neurons
    …& ataxia - abnormal movements in coordination (cerebellar involvement)
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46
Q

Extraoccular movements

A

CN 6 (abducens) - lateral rectus muscle, moves eyes laterally
CN 4 (trochlear) - superior oblique muscle, moves eyes down and rotate internally
CN 3 (oculomotor) - all other muscles of eye movement, raises eye lid, and mediates pupillary constriction

Damage to these CN - patients report seeing double vision

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47
Q

Pituitary vs. pineal gland

A

Pituitary gland - endocrine function, hormones for growth and development -
Press on optic chiasm

Pineal gland - melatonin production and circadian cycle regulation

tumor may obstruct cerebral aqueduct causing hydrocephalus or compress dorsal midbrain causing Parinaud’s syndrome

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48
Q

Glial cell (a.k.a. neuroglia)

A

Cell in white matter that provides structural support
Ex: Schwann, oligodendrocyte, microglia, ependymal, astrocyte

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49
Q

Brainstem structures

A

Brainstem = midbrain, pons, medulla
Motor and sensory tracts decussate below medulla and above spinal cord

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50
Q

Tegmentum vs Tectum

A

Tectum - dorsal (“ceiling”) part of the midbrain; consists of superior colliculi (receives input from retina and visual cortex, fx: tracking objects) and inferior colliculi (receives crossed and uncrossed auditory fibers)
- Posterior to cerebral aqueduct

Tegmentum - ventral (“floor”) part of the midbrain (origin of mesolimbic and mesocortical dopamine pathways)
Anterior to cerebral aqueduct

The cerebral aqueduct separates the tectum and tegmentum

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51
Q

Auditory pathway

A

Cochlea
Cochlear nucleus (medulla)
Superior olivary complex (pons)
Lateral lemniscus (pons) – area of partial decussation
Inferior colliculus (midbrain)
Medial geniculate nucleus (thalamus)
Auditory cortex (tonotopical)

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52
Q

Visual pathway

A

1 - Retina rods (periphery of retina, low levels of light and motion) and cones (center of your retina, distinguish color and detail)
2 - Optic nerve
3 - Optic chiasm (area of partial decussation) - becomes optic tract
(wraps around lateral surface of midbrain)
4 - Superior colliculus
5 - Lateral geniculate nucleus (thalamus)
6 - Optic radiations

a - inferior fibers (Meyer’s loop) pass through the temporal lobe; insult = pie in the sky
b - superior fibers of the optic radiations pass through the parietal lobe; insult = pie on the floor

7 - Visual cortex/calcarine fissure (retinotopical) – Brodmann area 17

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53
Q

Optic chiasm lesions produce

A

Bitemporal hemianopia (generally asymmetrical)

Optic chiasm lies on the ventral surface of the brain, therefore susceptible to compression by pituitary tumors

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54
Q

Optic radiations definition and fibers

A

The axons leaving lateral geniculate nucleus (LGN) travel laterally over temporal horn of lateral ventricles then back toward primary visual cortex in occipital lobe

Inferior fibers (Meyer’s loop) pass through the temporal lobe
insult = pie in the sky (contralateral superior quadrantanopia)

Superior fibers of the optic radiations pass through the parietal lobe
insult = pie on the floor (contralateral inferior quadrantanopia)

55
Q

Optic radiation insults

A

Inferior fibers (Meyer’s loop) pass through the temporal lobe

  • temporal lobe lesions (ex: middle cerebral artery, MCA) = pie in the sky (contralateral superior quadrantanopia)
    Also lesions on the lower bank of calcimine fissure cause this

Superior fibers of the optic radiations pass through the parietal lobe

  • parietal lobe lesions = pie on the floor (contralateral inferior quadrantanopia)
    Also lesions on the upper bank of calcimine fissure cause this
56
Q

Cortical blindness

A

Total or partial loss of vision caused by bilateral lesions to the primary occipital cortex

On examination:

  • Visual loss on confrontation testing but often anosognosia (completely unaware of deficit)
  • Pupils do respond to light (*ocular visual impairment = pupils don’t respond to light)
  • Loss of blink to threat

Causes:

-Congenital cortical blindness: Perinatal ischemic stroke, Meningitis, Encephalitis, TBI to occipital lobe

-Acquired cortical blindness: Lesions of the occipital cortex, Head trauma, Infection, Loss of blood flow to the occipital cortex (Unilateral or bilateral PCA blockage, Cardiac surgery)

57
Q

Visual streams

A

Higher-order visual processing via 2 streams

Dorsal “where” pathways
Project to the dorsolateral parieto-occipital association cortex
Analysis of motion and spatial relations
- Lies in the MCA–PCA watershed territory

Ventral “what” pathways
Project to the inferior occipitotemporal association cortex
Analysis of form: specific regions identifying colors, faces, letters, etc
- Supplied by the posterior cerebral artery (PCA)

*Primary visual cortex is supplied by the posterior cerebral artery (PCA

58
Q

Ventral (inferior occipitotemporal) stream syndromes

A

Visual agnosias - inability to identify visually presented material
- can recognize object in other sensory modalities (e.g., touch)

  • Apperceptive agnosias - inability to distinguish visual shapes, including recognizing, copying, or discriminating between different visual stimuli.
    Lesions: damage to the posterior sections of the right hemisphere.
  • Associative agnosias - impaired recognition/naming “recognition without meaning”; intact copying and discrimination
    Lesions: left occipito-temporal region
  • Prosopagnosia - unable to recognize people by looking at their faces; lesions in bilateral inferior occipitotemporal cortex (i.e., fusiform gyrus); if resulting from unilateral lesion, likely in the right hemisphere
59
Q

Fusiform gyrus

A

a.k.a. inferior occipitotemporal cortex

Responsible for visual categorization: number, letter, face, color

60
Q

Fusiform face area

A

Specialized for face recognition

Ventral surface of the temporal lobe on the lateral side of the fusiform gyrus

Usually larger in the right hemisphere

May also be important in recognizing fine distinctions between well-known objects (e.g., bird experts, sheep farmer)

lesions can result in prosopagnosia

61
Q

Dorsal (dorsolateral parieto-occipital) stream syndromes

A

Optic ataxia - impaired ability to reach for or point to objects in space under visual guidance
- Once an object has been touched, can perform smooth movements back and forth to it (not the case in cerebellar ataxia)

Ocular apraxia - difficulty voluntarily directing one’s gaze toward objects in the peripheral vision through eye gaze
- can result in difficulty scanning a visual scene
- hemorrhages in the parietal eye fields

Balint’s syndrome - often caused by MCA-PCA watershed infarcts, includes clinical triad:

  1. Simultanagnosia - Impaired ability to perceive parts of a visual scene as a whole (poor visual-spatial binding)
    Can perceive only one small region of the visual field as a whole
  2. Optic ataxia
  3. Ocular apraxia

Hemispatial neglect - Lesion to the posterior parietal cortex, typically right.
Visual neglect of the left-side of space = impairments in reporting, responding to, or orienting attention to the contralateral visual field

62
Q

Extraocular movement nerves

A

CN 3 - oculomotor nerve
all extraocular muscles, except for superior oblique and lateral rectus

CN 4 - trochlear nerve
Superior oblique muscle; causes depression and intorsion of the eye. Moves eye down when looking towards nose, also rotates internally

CN 6 - abducens nerve
Lateral rectus muscle; causes abduction of the eye (causes eye to turn outward)

63
Q

Extraocular nerve insults

A

CN 3 - exotropia (eye deviates outward, vertical or medical movements are difficult, lateral diplopia, ptosis (upper eyelid droops), dilated pupil, due to severe TBI

CN 4 – bilateral lesions common, vertical diplopia (double vision), head tilt contralateral

CN 6 – eye turned in (esotropia)

64
Q

Cingulate cortex

A

Part of the limbic cortex with the parahippocampal area

Fx: Determines saliency of stimuli and associated emotion/motivation

Limbic system:
- limbic cortex (cingulate gyrus + parahippocampus gyrus)
- hippocampal formation
- amygdala

65
Q

Limbic system

A
  • limbic cortex (cingulate gyrus + parahippocampus gyrus)
  • hippocampal formation
  • amygdala
66
Q

Striatum

A

The input module to the basal ganglia

The striatum is composed of two divisions:
- dorsal (caudate, putamen)
- ventral (nucleus accumbens, olfactory tubercles)

Regulates motor behaviors and responses to rewarding and aversive stimuli.

67
Q

Internal capsule function

A

Allows communication between areas of the cerebral cortex and areas of the brainstem.

These connections are made possible by the pathways of the internal capsule and are necessary for physical movement and perception of sensory information

68
Q

Internal capsule location

A

White matter structure of the brain, located in the medial part of each cerebral hemisphere (lateral to the thalamus and caudate nucleus)

69
Q

Parietal lobes

A

Superior parietal lobe - sensory motor integration, body schema, spatial processing

Inferior parietal lobe - complex spatial attention, self-awareness, integration of tactile sensation
Gerstmann’s syndrome (left)
Apraxias (ideational, ideomotor)
Anosognosia (right)
Hemineglect (right; most severe in inferior)

Temporoparietal junction (TPJ) -
language comprehension (left): contains Wenicke’s and angular gyrus
- takes spoken and written language and connects them to existing knowledge, memories

sound/music comprehension (right)

70
Q

Temporal lobes

A

Superior temporal gyrus - speech sound perception (left; Wernicke’s), nonverbal tonal sequence (right)

Medial temporal gyrus - memory and learning (temporal limbic circuit)

Inferior temporal gyrus - object and visual identification and recognition (ventral stream: colors and objects)

71
Q

Medial temporal lobe circuits subserving memory

A

Lateral limbic circuit:
Amygdala -> thalamus -> orbitofrontal lobe -> amygdala
amygdala is more lateral than hippocampus

Medial limbic circuit:
Hippocampus -> thalamus -> cingulate cortex -> hippocampus

Dense amnesia occurs with disruption to BOTH circuits

72
Q

Perirhinal/parahippicampal cortex

A

cortical structure

Implicated in episodic memory processing

Projects to the hippocampal memory system.

damage can result in amnesia

73
Q

Orbitofrontal region damage

A

disinhibition (in charge of response inhibition), emotional lability, reduced empathy, Witzelsucht (compulsive/inappropriate joking)

changes in personality, behavior, and affect

Function: emotion regulation (hot core)

74
Q

Ventromedial region damage

A

disordered reward/punishment processing

shares region with orbitofrontal and limbic system

75
Q

Dorsolateral region damage

A

Dysexecutive syndrome

Function: EF, working memory, attention, persistence, perseveration, sustained attention

76
Q

Dorsomedial region damage

A

bilateral insult: apathy and mutism

function: behavioral activation, motivation

connects with anterior cingulate cortex, which damage can lead to mutism, impaired initiation, akinesia (decreased movement; (intentional disorders))

77
Q

Mesostriatal dopamine pathway

A
  • arises from substantia nigra and projects to the striatum (caudate and putamen) in BG. (Meso= middle brain/midbrain, striatal = striatum; input from BG)

** The substantia nigra (SN) is a basal ganglia structure located in the midbrain that plays an important role in reward and movement.**

  • pathway implicated in Parkinson’s disease, and dysfunction here can produce disabling motor and nonmotor symptoms
78
Q

Mesolimbic dopamine pathway

A
  • arises in ventral tegmental area and projects to the medial temporal lobe, amygdala, cingulate cortex
  • key role in reward functioning and has been implicated in addictive behavior/drug use
  • overactivity = positive symptoms of schizophrenia
79
Q

Mesocortical dompamine pathway

A
  • arises from the ventral tegmental area and projects primarily to cortical regions of the frontal lobe.
  • key role in EF, working memory, top-down attention, and initiation of motor activity.
    Dysfunction = negative symptoms of schizophrenia, as well as dysexecutive syndrome and bradykinesia.
80
Q

Anterior cingulate function

A
  • integrates information from emotion/motivational systems and frontal-cortical system, thus allowing conflict resolution between two processes that may be competing for attention or output channels.
  • motivating selective attention toward a salient stimulus
81
Q

CN involved in gag reflex

A

9 and 10 (inches make you gag)

82
Q

Basal ganglia

A

Comprised of the:

dorsal striatum (caudate nucleus “C-shapes” and putamen)
- ventral striatum (nucleus accumbens and olfactory tubercle)
- globus pallidus
- ventral pallidum
- substantia nigra
- subthalamic nucleus.

83
Q

Pituitary adenoma

A

Growth on the pituitary gland

Can lead to endocrine/hormone dysfunction (e.g., menstrual changes, sexual dysfunction)

Can compression optic chiasm, resulting in visual field defect

84
Q

Pineal gland tumor

A

Can compress cerebral aqueduct, leading to hydrocephalus and Parinaud’s syndrome

85
Q

Pyramidal motor tracts

A

“pyramid” and “bulbar” = medulla

  • Corticobulbar tract = cortex to medulla
  • Corticospinal tract = cortex to spinal cord (lower motor neurons

decussate at medulla

86
Q

“spasticity” vs. “ataxia” vs. “dyskinesia”

A

Spasticity - upper motor neuron

Ataxia - cerebellum

Dyskinesia (abnormal movement) - basal ganglia dysfunction

87
Q

Damage to the dorsomedial PFC and anterior cingulate cortex leads to…

A

mutism, impaired initiation, akinesia (decreased movement)

88
Q

Leukoaraiosis

A

nonspecific loss of density of subcortical white matter long been believed to be caused by perfusion disturbances within the arterioles perforating through the deep brain structures.

89
Q

Is alexithymia a right or left hemisphere dysfunction?

A

typically seen more often in right hemisphere dysfunction

90
Q

Ideational vs. ideomotor apraxia

A

Ideomotor apraxia: difficulty pretending/gesturing to use common objects (hammer, saw, screwdriver). Patients use their hand as the tool rather than gesturing the use.

Ideational: failure of sequential movement and that makes up purposeful behavior (brushing teeth). Patient get lost in the steps

91
Q

Microscopic infarctions, white matter hyperintensities, silent brain infarcts and microhemorrhages secondary to cerebral amyloid angiopathy are…?

A

commonly observed in community-dwelling older adults, even in the absence of cognitive impairment

92
Q

Overall, the most common medically unexplained symptom in children and teens is ____, with younger children more likely to report ____.

A

headache

abdominal distress

93
Q

What is the fornix?

A

The fornix is the primary output destination for the hippocampus. Degeneration of axons in the hippocampus may result in Wallerian degeneration and resultant atrophy in the fornix.

94
Q

Effects of vestibular dysfunction on eye movements are contralateral or ipsilateral?

A

Ipsilateral

95
Q

In the classic cortico-striatal-pallidal-thalamo-cortical loop, the “input” to the basal ganglia is to the ____ and the output is via the ____.

A

striatum

globus pallidus.

The striatum (caudate and putamen) receives cortical input and projects to the globus pallidus, which provides basal ganglia output to the thalamus.

96
Q

What happens when parahippocampal region is lesioned/damaged?

A

Significant amnesia can be produced.

97
Q

There is anatomic evidence of separate visual channels for:

A

form, color, and motion

98
Q

Damage to the medial frontal cortex is primarily associated with:

A

intentional disorders (apathy, bradykinesia)

99
Q

What sign is likely due to a disconnection rather than direct damage to a module?

A

Any sensory specific cognitive deficit is likely a disconnection problem. (ex: modality-specific anomia unable to name visual objects, but can name with tactile presentation).

100
Q

Romberg test

A

patients are asked to stand with their feet together and close their eyes. The “Romberg sign” is when unsteadiness occurs within several seconds of closing the eyes. Evaluates cerebellar function, along with heel-shin test

101
Q

Epidural vs subdural hematoma

A

Subdural hematoma results from rupture of bridging veins between sulci on the upper surface of the brain

Epidural hematoma develops in the potential space between the dura and the skull, typically due to rupture of the meningeal artery following fracture of the temporal bone

102
Q

Dysmetria

A

refers to inaccurate unilateral fine motor coordination and is considered to be a sign of cerebellar dysfunction.

103
Q

Lesions to the basal forebrain produce amnesia because:

A

cholinergic/acetylcholine inputs to the hippocampus and amygdala are disrupted (because the basal forebrain provides cholinergic innervations of the hippocampus and amygdala system)

104
Q

Heschl’s gyrus is associated with which cortex

A

primary auditory cortex

is the gyrus on the upper surface of the temporal lobe that contains the primary auditory cortex

105
Q

Damage involving the cribriform plate likely affects which cranial nerve?

A

Olfactory

olfactory nerve travels across the cribriform plate of the ethmoid bone to synapse in the olfactory bulbs

sense of smell may be lost following head trauma due to damage to the olfactory nerves

“babies in CRIBs smell”

106
Q

Bulbar palsy

A

Bulbar palsy is a set of conditions that can occur due to damage to the lower cranial nerves (CN 9-12)

Clinical features of bulbar palsy range from difficulty swallowing and a lack of a gag reflex to inability to articulate words (dysarthria) and excessive drooling.

Bulbar palsy is most commonly caused by a brainstem stroke or tumor.

Palsy = weakness

emotions are not affected (compared to pseudobulbar palsy)

107
Q

Describe lateral versus medial cerebellar lesions

A

Lateral - limb coordination and motor planning

Medial - trunk control, posture and balance, and gait

Damage to cerebellum will result in difficulty controlling ipsilateral side with full awareness of its abnormal movement

108
Q

Describe white/gray matter make up between left/right hemisphere

A

Right hemisphere has more white matter, less gray matter, more association cortex, and more interconnections

109
Q

Which areas of the brain are myelinated first? Sensory or motor areas?

A

Sensory

110
Q

Hippocampus is involved in the ?? of memories, not the ??

A

formation,
retrieval

111
Q

Planum temporale is commonly known as?

A

Wernicke’s area

112
Q

Describe the Geschwind-Galaburda Theory

A

Planum temporale (Wernicke’s area) is asymmetrically large in the left hemisphere. In males, asymmetry is less, proposed to be the effect of testosterone in delaying the development of the left hemisphere with greater development of the right

Rationale: greater spatial skills in males and greater language skills in females, also increased rate of autoimmune disorders in males

113
Q

Heschl’s gyrus vs. Wernicke’s area

A

Heschl’s gyrus - process the auditory qualities of sound (direction of auditory stimuli, pitch, loudness rather than words for their linguistic properties) - bilaterally symmetrical

  • auditory stimulation from Heschl’s gyrus reflects auditory stimulation from the contralateral ear

Wernicke’s area (aka planum temporale) - linguistic processing - larger in the dominant hemisphere

114
Q

MAGNOCELLULAR vs. PARVOCELLULAR PATHWAYS

A

These are layers of the dorsal lateral geniculate nucleus (LGN)

The magnocellular pathway carries information about large, fast things (low spatial frequency, high temporal frequency) and is colorblind.

The parvocellular pathway carries information about small, slow, colorful things (high spatial frequency, low temporal frequency).

115
Q

Telencephalon

A

a.k.a. cerebrum (cerebral cortex, subcortical white matter, and basal ganglia)

116
Q

Papez circuit

A

known as medial limbic circuit, which is a neural circuit for the control of emotional expression

Hippocampal formation → fornix → mammillary bodies → thalamus → cingulum → entorhinal cortex → hippocampal formation.

117
Q

People born without a corpus callosum…

A

are behaviorally indistinguishable from people born with CC

118
Q

Bell-Magendie law

A

The concept that the dorsal portion of the spinal cord is sensory in function while the ventral portion is motor

119
Q

Difference in function between anterior commissure and the corpus callosum

A

Anterior commissure allowed for olfactory system connections between hemispheres.

Both interconnect the amygdalas and temporal lobes, contributing to the role of memory, emotion, speech and hearing.

120
Q

What cells produce myelin in the CNS and PNS?

A

COPS

CNS myelin is produced by special cells called oligodendrocytes.

PNS myelin is produced by Schwann cells.

121
Q

Bilateral damage to the auditory cortex results in

A

cortical deafness

122
Q

What carries the majority of inputs to and outputs from the hippocampus formation?

A

Entorhinal cortex

Information “Enters” the hippocampus

123
Q

Reuptake of a neurotransmitter is accomplished by the…?

A

Presynaptic neuron

124
Q

Describe damage to a frontal eye field

A

Unilateral frontal eye field lesions tend to cause contralateral saccadic eye movement impairment

Destruction of the FEF causes deviation of the eyes to the ipsilateral side

125
Q

What part of the brain produces saccadic eye movements?

A

The commands for horizontal components of saccades originate in the brainstem (pons and medulla)

126
Q

Argyll Robertson pupils definition

A

characterized by small and irregular pupils (most often bilateral) that have little to no constriction to light but constricts briskly to near targets (light-near dissociation).

…in other words will not react to light but can accommodate to near object

127
Q

Argyll Robertson pupils are diagnostic of…

A

Neurosyphilis

128
Q

Describe right and left handedness prevalence & language dominance

A

firmly established by age 9

General population: right-handedness (90%), left-handedness (10%) - determined by writing

Left hemisphere language dominance (96% right-handed; 70% left-handed)

Of the remaining 30% left-handers: 15% had R hemisphere language dominance and 15% had bilateral language dominance (conformed via Wada test)

129
Q

Which factors determine nerve impulse speed in axons?

A

Axon diameter and myelination

130
Q

Metencephalon vs. myelencephalon

A

metencephalon - pons and cerebellum

myelencephalon - medulla

131
Q

Function of arachnoid granulation

A

small protrusions of the arachnoid mater (the thin second layer covering the brain) into the dura mater (the thick outer layer)

allow cerebrospinal fluid to exit by functional holes through the subarachnoid space and enter the bloodstream

132
Q

Which sensory system has NO crossed connections in the brain?

A

Olfactory

133
Q

Describe movement of ions

A

KONAN (K out, Na “in”)

In order for action potential to occur:
sodium (Na-) rushes in
potassium (K+) rushes out and

134
Q

5 divisions of the brain

A

Telencephalon
- Cerebrum
Diencephalon
- Thalamus
- Hypothalamus
Mesencephalon
- Midbrain
Metencephalon
- Pons
- Cerebellum
Meyelencephalon
- Medulla