Final Exam (Exam 3 stuff) Flashcards
Functions: i.Sensory 1. Somatic sensory (Se) 2. Special sensory (SS) 3. Visceral sensory (SV) ii.Motor 1. Somatic/Branchial motor (Mo) 2. Parasympathetic motor (MP)
Foramen Magnum
- exit for spinal cord
- by far the biggest hole in skull (point of herniation)
External carotids feeds what?
-the face, skull, and meninges
Pterion
- weakest poing in skull
- immediately overlies middle meningeal artery
- bleeding outside meninges can cause epidural hematoma (EDH)
Meninges (layers?)
- pia mater
- arachnoid mater
- dura mater
- spinal cord vs brain
- in spinal cord, subarachnoid space is enlarged.
Cranial arteries (location and cause of what?)
- in subarachnoid space
- cause of subarachnoid hemorrhage (SAH)
Cranial Vasculature: Anterior circulation
Internal Carotid Artery (ICA)
splits into anterior and middle cerebral arteries
Anterior Cerebral Artery (ACA)
- provides blood supply to medial brain
- most noticeable function is sensory/motor for legs
Middle cerebral artery (MCA)
- Lenticulostriate branches feed basal ganglia and internal capsule
- Distal branches feed sensory/motor to arms/face and many language areas (on dominant side, usually left)
Cranial Vasculature: Posterior circulation
-Vertebral arteries (posterior cerebral artery)
Posterior Cerebral Artery (PCA)
- visual cortex
- visual association areas
Cranial Vasculature: Veins
- Dura mater sinuses
- Cortical veins
- Bridging veins
Bridging veins cause what?
-cause subdural hematoma (SDH)
Stroke terminology
- Ischemic (blockage)
- Hemorrhagic (bleeding)
Hemorrhagic (ICH and SAH)
ICH = intracerebral hemorrhage SAH = subarachnoid hemorrhage
Blood Brain Barrier (BBB)
Passive::
1) tight junctions btwn endothelial cells
2) astrocyte foot processes
Active::
1) astrocytes pump chemical back into blood
Cerebrospinal fluid (CSF): Ventricular system
1) continuous circulation from inside ventricles down spinal cord
2) product of the inside of the original neural tube
Cerebrospinal fluid (CSF): production
1) Choroid plexus
2) Ependymal cells on inside of ventricles
Cerebrospinal fluid (CSF): Absorption
1) Arachnoid granulations
- pushes CSF back into dural sinuses (venous blood)
Monro-Kellie doctrine
- 3 things in brain (blood, brain, and CSF)
- an increase in the size of one (i.e., tumor) leads to a decrease in one of the others out the foramen magnum (i.e., blood or brain tissue)
Cushing’s triad - response to increased ICP
- Bradycardia (slow heart rate)
- Hypertension (increase blood pressure)
- Irregular breathing (hyperventilation)
Herniation
- final outcome of uncontrolled ICP
- brain herniates out foramen magnum, leading to compression of brain stem, and death
Causes of increased ICP
1) Hydrocephalus
- clogged CSF circulation leading to backup in brain
- very dangerous
2) turmors
3) cerebral edema (from trauma)
Brainstem divisions
Midbrain
Pons
Medulla
Cranial nerve: Surface anatomy
CN 1-2 on underside of brain CN 3-4 around midbrain CN 5 from side of pons CN 6-8 from under pons CN 9-12 in medulla
CN 1 - Olfactory Nerve
1) Function: Smell (Special sense)
2) Test: different scents
3) Pathways:
- olfactory bulb, olfactory cortex, Amygdala
4) clinical correlates:
- anosmia (loss of smell) in trauma
- Emotional link to scents
CN II - Optic Nerve
1) Function: vision (special sensory)
2) Test: Visual acuity
3) pathways
- lateral geniculate nucleus = conscious vision
- superior colliculus - coordinate eye movement
4) clinical correlates:
- pituitary/hypothalamus tumors affected by vision
- stroke localization (peripheral vs. central lesions)
CN III - Oculomotor nerve
1) Func:
- motor for eye movement (Mo)
- eyelid retraction (Mo)
- pupil constriction (MP)
2) test
- move eye in cardinal directions. up down and in?
3) Palsy: “Down and out” eye is lateral and inferior facing
- Parasympathetic fibers are on outside of nerve, so benign vascular pathologies (like diabetes) tend to spare the pupil, while dangerous pathologies (like an aneurysm) tend to “blow” the pupil
CN IV - trochlear nerve
1) Func:
- motor to superior oblique (Mo) = down and inward
2) palsy: nasal upshoot - when eye moves medially, it is superiorly displaced
- bcuz it exits the back of midbrain and curls around brainstem it is commonly injured in trauma
- frequently found to be congenital, but missed for a long period of time bcuz it is easy to miss
CN V - trigeminal nerve
1) Function:
- cutaneous sensation to face (Se)
- muscles of mastication (Mo)
2) test
- light touch to lower face, cheeks, and forehead
CN VI - abducens
1) function
- motor to lateral rectus (Mo) = controls eye movement laterally
2) palsy: cross-eye = unable to move one eye laterally
- frequently happens congenitally
- bcuz 6th nerve exits below pons, it is very sensitive to brain displacement due to increased ICP
CN VII - facial nerve
1) function:
- motor to muscles of facial expression (Mo)
- parasympathetic to salivary glands (MP)
- tast from anterior 2/3rds of tongue (SV)
2) test
- symmetric smile, squeeze eyes shut, wrinkle forehead
CN VIII - vestibulocochlear nerve (auditory)
1) function:
- hearing (SS)
- vestibular sensation (SS)
2) Test
- Rinne, Weber, Tonotopy; tilt table
CN IX - glossopharyngeal nerve
1) function:
- palatal elevation (Mo)
- parotid salivary gland (MP)
- sensation in pharynx (Se)
- tast for posterior 1/3 of tongue (SV)
2) Test
- say “ahhh”, watch for palate elevation
3) palsy:
- impaired elevation of palate on that side, uvula deviates towards unaffected side.
CN X - vagus nerve
1) function:
- swallowing (Mo)
- larynx/voice (Mo)
- parasympathetic to body (MP)
- sensation from pharynx (Se)
2) test
- is their voice hoarse?
CN XI - spinal accessory nerve
1) function:
- sternocleidomastoid and trapezius
2) test:
- turn head, shoulder shrug
CN XII - hypoglossal nerve
1) function:
- tongue movement (Mo)
2) test:
- stick tongue straight out
3) palsy:
- tongue will deviate towards affected side.
Tongue sensation (nerves)
Anterior = trigeminal posterior = glossopharyngeal
Tongue taste (nerves)
anterior = facial posterior = glossopharyngeal
Tongue motor (nerves)
= hypoglossal
Eye anatomy
Retina
Pupil / iris
Cornea
Sclera
Lens and refractive properties
- To form a clear image, light must converge on retina
- Changes in focus (accommodation) performed by ciliary muscles stretching lens
- Myopia, Hyperopia, Presbyopia
Myopia
(nearsighted)
- light focuses anterior to retina
Hyperopia
(farsighted)
- light focuses posterior to retina
Presbyopia
- lens fails to relax, unable to focus on near objects
Retina surface anatomy
- Blood vessels
- Fovea (avascular, dense in high acuity cones)
- Optic disc (blind spot)
Retina development
1) eye forms as direct extension of neural tube (optic vesicle)
2) optic vesicle folds into itself to form optic cup
- distal layer = neural retina
- proximal layer = pigmented epithelium
Retina cellular structure (Layers from back of eye to front)
1) pigmented epithelium
2) Outer nuclear layer
3) outer plexiform layer
4) inner nuclear layer
5) inner plexiform layer
6) Ganglion cell layer
7) nerve fiber layer
Pigmented epithelium
- Provides dark backdrop to reduce light scatter
- Involved in photoreceptor maintenance and pigment turnover
Outer nuclear layer
Photoreceptors (rods and cones)
Photoreceptors: Rods
- Low light - can respond to single photons
- Slow adapting
- Low acuity, highly convergent
- No color content
- Highly sensitive to motion
- Located in periphery
Photoreceptors: Cones
- Need more light, >100 photons
- Fast adapting
- High acuity, low convergence
- Specialized for particular color
- Located on fovea
Outer plexiform layer
Horizontal cells
- integrate across multiple photoreceptors.
Inner nuclear layer
Bipolar cells
-connects outer layer to ganglion layer
inner plexiform layer
Amacrine cells
- located btwn bipolar and ganglion cells
- integrates horizontally
Ganglion cell layer
Ganglion cells
-final output cell of retina
nerve fiber layer
- axons from ganglion cells
- coalesce to form optic nerve
Phototransduction
Before stimulation:
- in the absence of light, cGMP is present and activates cation channels (depolarizes cell)
- 11-cis retinal retinal is bound to an opsin
Stimulation:
- light converts 11-cis retinal to all-trans after absorbing photon.
- opsin activates transducin
- transducin activates phospodiesterase (PDE), which cleaves cGMP
- reduction in cGMP closes cation channels and hyperpolarizes cell
Resetting cycle:
- opsin phosphorylated by opsin kinase and deactivated by protein arrestin
- all-trans retinal converted back to 11-cis retinal through retinoid cycle in pigmented epithelium
2 populations of ganglion cells:
- on-center vs off-center
On-center:
- activated by light within their center
- inhibited by light in their surrounding
Off-center:
- inhibited by light within their center
- activated by light in their surround
Vision: Edge detection
- Under diffuse lighting, there is equal activation/inhibition from the center/surround, and no net activation
- If the ganglion cell field crosses an edge of light, there will be a difference in the center/surround leading to a net positive or negative response
- Hermann grid illusion
Vision: Light adaptation
-Ganglion cells respond only to differences in center/surround, and so are less sensitive to absolute light levels
Color vision: Cones
- Respond to different frequency ranges
- Classified as Short (S), Medium (M), and Long (L) frequencies, roughly equivalent to the colors blue, green, red
- M/L make up 90% of cones
Color vision: color opponency
- Based on differences in response of cones (not absolute activation)
- Difference in S vs. M/L cones = blue/yellow
- Difference in M vs. L cones = red/blue
Color vision: deficits
usually a lack of M or L cones
Central organization: Visual fields
- The area that each eye sees can be subdivided into four quadrants
- Each quadrant of space is seen partially by each eye
Central organization: Optic chiasm
- The optic nerves meet and some fibers cross, while others stay ipsilateral
- The result is that all fibers from both eyes from one side of the visual field end up on the contralateral side of the brain
Central organization: Higher processing
- All of the central processing centers work with information from visual fields, not individual eyes
- However, the information from each eye is still maintained separately in many cortical areas
- Cortical arrangement is biased for foveal vision, similar to the homonculous of the motor/sensory system
Central organization: Deficits
Anopsia: “visual field cut”
Scotomas: small spots of vision loss
Patterns of visual loss
1. Monocular blindness 2. Bitemporal hemianopsia 3. Homonymous hemianopsia 4. Homonymous quadrantanopsia 5. Hemianopsia with macular sparing
Central visual pathways:
Primary visual pathway (retinogeniculostriate)
- Projects to lateral geniculate nucleus (LGN)
- Continues to Striate cortex (primary visual cortex; V1) by way of the optic radiations
Central visual pathways: Light reflex
- Projects to pretectum in midbrain
- Continues to Edinger-Westphal nucleus, which sends parasympathetic output through CN III (pupillary constriction)
Central visual pathways: Eye Movement
-Projects to superior colliculus
Central visual pathways: Circadian rhythm
-Projects to suprachiasmatic nucleus of hypothalamus
Cortical processing: Striate cortex
Neurons sensitive to properties of groups of ganglion cells
1. Edge orientation 2. Direction of motion 3. Spatial frequency 4. Temporal frequency
Ocular dominance columns
1. Paired columns of cells that represent individual inputs from each eye 2. Differences imply perspective
Cortical processing: Extrastriate regions
- Motion
- Color
- Faces
Cortical processing: Dorsal/Ventral streams
- Dorsal: “where” spatial
- Ventral: “what” visual
sound properties
Pressure waves through air
Frequency/wavelength
i. Fourier transform
Amplitude
Audible soundsWhat is the audible range of sounds for humans?
- 20Hz to 20kHz
- High frequency range declines with age
External ear (anatomy)
- Pinna
- External auditory meatus
- Tympanic membrane
External ear: Pinna
Filters sound to give cues to source location
External ear: External auditory meatus
Amplifies low frequency sounds (~3 kHz)
Middle ear (anatomy)
- Ossicles
- Muscles
- Oval window
- round window
Ossicles of middle ear (func. and bones)
Funct: Transmits pressure waves from tympanic membrane to oval window
Bones:
- Malleus
- incus
- stapes
Muscles of middle ear
- Tensor tympani
- stapedius
***dampen the vibration of the ossicles to mute sound transmission
Inner ear anatomy
- cochlea
- labyrinth
Cochlea
- Coiled tube with 3 chambers, separated by membranes
- Outer tubes are connected to one another, and start at the oval window, end at the round window
- Basilar membrane
- Organ of Corti
- Hair cells
- Ionic gradient
- Cochlear amplifier
Cochlea: Basilar membrane
- Varies in width and stiffness
- Base most sensitive to high frequencies
- Tip most sensitive to low frequencies
Cochlea: Organ of Corti
- Layer of cells including hair cells on top of basilar membrane
- Tectorial membrane on top
- Hair cells send projections to spiral ganglion
Cochlea: Hair cells
- Inner hair cells - sound transmission
- Outer hair cells - cochlear amplifier
- Contain groups of cilia attached to the tectorial membrane
- Deflection manually opens cation channels via tip links (very fast and sensitive to small deflections)
- Also very sensitive to damage
Which hair cells of the cochlea transmit sound?
inner hair cells
Which hair cells of the cochlea amplify?
outer hair cells
Ionic gradient (cochlea)
- Inner chamber (containing tips of hair cells) very high in potassium
- Outer chamber has normal extracellular concentrations (low in potassium)
- Hair cells depolarize by opening K-channels into inner chamber
- Hair cells repolarize by opening K-channels into outer chamber
- Because it uses two different compartments, it does not need to reestablish a gradient, and can continuously depolarize
Cochlear amplifier
- Outer hair cells can produce vibrations at the dominant frequency to amplify incoming sounds
- Can be used in otoacoustic emissions to test cochlear function
Weber Test
- bypasses air conduction
- tests for inequalities in sensorineuroconduction
Rinne Test
- Compares air vs bone conduction
- normally air > bone
Vestibular System
- Measures deviations in body/head movement relative to gravity
- Integrates across multiple sensory modalities
- Multiple reflex arcs make most functions fast and automatic
Vestibular system: Labyrinth
a. Otolith organs
b. Semilunar canals
Otolith organs of labyrinth
- Utricle and saccule
- Responsive to linear acceleration and static position
- Structure
- Hair cells
- Gelatinous layer
- Otoconia - “stones”
-Divided in two by striola; cell response opposite to each other
Which otolith organ does horizontal movement?
Utricle
Which otolith organ does vertical movement?
Saccule
Semilunar canals (labyrinth)
-Responsive to rotational acceleration
- Hair cells
- Very similar to cochlear cells
- Shared fluid space with cochlea
- Responds to displacements from fluid currents
- Cupula hair cells only depolarize in one direction
- Leftward head rotation depolarizes the left semilunar canal, and hyperpolarizes the right
Central vestibular pathways: Integrate information from?
- Otolith organs / semilunar canals
- Visual system
- Cerebellum
- Somatic sensory system
Central vestibular pathways: Initial pathway
- Scarpa’s ganglion
- Vestibular nerve (CN VIII)
- Vestibular nuclei in medulla
Vestibulo-ocular reflex
- Reflex ocular movements to oppose head movements
- Vestibular nucleus projects to contralateral abducens nucleus via the MLF
Vestibulo-cervical reflex
-Keeps head upright when body is moving (or falling)
Vestibulo-spinal reflex
- Postural reflex to try to keep body upright
- Produces a general extensor tone in body
Vestibular testing bedside
- “Doll’s eyes” vestibulo-ocular reflex
- Cold calorics (generally only in comatose patients)
Vestibular testing in clinic
- Rotating chair
- Electronystagmography / Videonystagmography
What is language?
- Language is the manipulation of abstract symbols that map onto specific meanings
- Language is uniquely human
- Not merely communication or learned associations
- It allows us to describe things that aren’t in front of us, or may not exist, and transmit that information efficiently through different modalities
Characteristics of language
- Lexicon
i. Orthography (correct spelling)
ii. Phonology (speech sounds) - Semantics (study of meaning)
- Symbol manipulation
Expressive aphasia
Non-fluent speech, choppy, slow
Receptive aphasia
- Paraphasias, use of incorrect words
- Comprehension deficit, not following commands
Global aphasia
- All basic language areas affected
- nothing
conduction aphasia
-Independently can produce/understand speech, but problems coordinating in certain conditions
Written language: (aphasia)
Alexia: impaired reading
Agraphia: impaired writing
Language: Frontal regions
- Broca’s area, inferior frontal gyrus
- Involved in speech production
- Damage leads to expressive aphasia
Language: Temporal regions
- Wernicke’s area, posterior superior temporal gyrus
- Involved in language comprehension / meaning
- Damage leads to receptive aphasia
- Also contains regions for phonology (speech sounds)
- Can cause categorical deficits
Lateralization of language
- Gradient, not absolute
- dominantly left in most people
Language: Non-dominant functions
- Prosody (rhythm, stress, and intonation of speech)
- Non-verbal language
- Music
Language: Importance of connectivity
-Conduction aphasia
- Corpus callosotomy
- Disconnects two hemispheres
- Stimuli presented only to non-dominant hemisphere cannot be named
Mapping: Wada test
- Test laterality by selectively anesthetizing one hemisphere
- Invasive, unreliable, no evidence supporting conclusions
- Other methods proven more predictive
Mapping: functional imaging
- Currently statistically the best method, non-invasive, relatively cheap
- Not currently adopted widely
Mapping: Electrocorticography
- Direct stimulation of cortex in an awake patient
- Used mostly in surgery to guide resections
Comparison to American Sign Language
a. History
b. Creole, mixtures of languages
c. Regional dialects
d. Grammar
e. Inflections
Cognition: Principles of organization
- Phrenology
- Localized vs. generalized
Cognition: Neural networks (mathematical concept)
- Non-linear mapping
- Learning phase, to behavioral production
Cognition: Association cortex
- Receives inputs that have already been processed by a primary cortex
- Have many connections to other cortical areas, as well as inter-hemispheric connections
Cognition: Association cortex - involved in???
- Extracting complex patterns from sensory information (e.g., facial processing)
- Mapping between senses (e.g., producing the correct pronunciation of a written word)
Parietal lobe (specific functions)
- Neglect
- Loss of attention
- Primarily associated with right-sided damage
- Gerstmann’s syndrome (left-parietal deficit)
- Agraphia
- Acalculia
- Finger agnosia
- Left-right confusion
- Balint’s syndrome
- Simultagnosia
- Optic ataxia
- Ocular apraxia
-Gerstmann’s syndrome (left-parietal deficit)
- Agraphia
- Acalculia
- Finger agnosia
- Left-right confusion
-Balint’s syndrome
Parietal lobe (specific functions
- Simultagnosia
- Optic ataxia
- Ocular apraxia
Temporal lobe (function)
Object recognition
Frontal lobe (function)
Working memory
1.Wisconsin Card Sorting Task
Personality
1. Phineas Gage 2. Frontal lobotomies
Frontal lobe deficits
- Inhibition (go-no-go) / appropriateness
- Perseveration
- Planning
- Disordered thinking
Delirium
i. Acute confusional state
ii. Dominant components: attention, orientation
iii. Frequently reversible
Dementia
Chronic cognitive deterioration
Dominant components: memory, cognition
Usually permanent
Delirium / dementia testing
- Mini-Mental State Exam (MMSE)
- Montral Cognitive Assessment (MoCA; www.mocatest.org)
