8 - Central Nervous System Flashcards
1
Q
What Secondary brain structures give rise to Adult brain structures?
list them
A
- Telencephalon -> cerebrum, lateral ventricles
- Diencephalon -> diencephalon, 3rd ventricle
- Mesencephalon -> Midbrain (brain stem), cerebral aqueduct
- Metencephalon -> Pons (brain stem) & Cerebellum, 4th ventricle
- Myelencephalon -> medulla oblongata (brain stem), Central canal
2
Q
What are the Axis of the brain?
Rostral, caudal, dorsal & ventral
A
- rostral - anterior
- caudal - posterior
- dorsal - superior
- ventral - inferior
3
Q
What are the main Adult brain regions?
A
- Cerebral hemispheres
- Diencephalon
- Brain stem – midbrain, pons & medulla
- Cerebellum
4
Q
What are the Cerebral lobes?
A
- Frontal lobe
- Parietal lobe
- Temporal lobe
- Occipital lobe
- Insular lobe
5
Q
What are the Cerebral Hemisphere Markings?
A
- Central Sulcus - separates precentral & post central gyrus
- Lateral sulcus - frontal & parietal lobes
- Transverse cerebral fissure - cerebrum from cerebellum
- longitudinal fissure - left & right cerebral hemispheres
- parieto-occipital sulcus - parietl & occipital lobes
- calcarine sulcus - separates primary visual cortex
6
Q
What layers protect the brain?
A
- SCALP
- Skin, CT, Aponeurosis, LCT, Pericranium
- Bone (skull)
- Blood-brain barrier
- Membranes (meninges)
- Watery cushion (CSF)
7
Q
What is the blood brain barrier & what does it do?
A
- Helps maintain stable envmt for brain
- Physically separates neurons from certain bloodborne substances
- Acts as a metabolic barrier
- Surrounds majority of brain tissue
- Tight junctions b/w endothelial cells is the key structure to the blood-brain barrier
8
Q
Blood-brain Barrier Transport Routes
A
- Paracellular – doesn’t typically happen, not a practical route
- Transcellular – lipophilic, efflux pump shoots it back out
- Inhibit – more can get through, some drugs are efflux inhibitors
- Transport proteins – bring in energy molecules, ex. Glucose
- Receptor-mediated transcytosis – ex. Insulin
- Absorptive transcytosis
9
Q
What are the Meningeal layers and what do Meninges do?
A
- dura mater, arachnoid mater, pia mater
- Cover & protect CNS
- Divides skull into parts
- Protect blood vessels & enclose dural venous sinuses
- Contain cerebrospinal fluid (CSF)
10
Q
What are the functions of CSF?
A
- Gives buoyancy to brain
- Protects CNS from blows & trauma
- Nourishes brain & carries chemical signals
- Clears wastes
11
Q
What are the Ventricles? Path through them?
A
lateral ventricle > Interventricular foramen > 3rd ventricle > cerebral aqueduct > 4th ventricle > median aperature, lateral aperature, central canal
12
Q
What are the Dural Venous Sinuses?
A
- Superior Sagittal sinus
- Inferior Saggital Sinus
- Straight sinus
- Transverse sinus
- Sigmoid sinus
- Internal Jugular vein
13
Q
What is the Path of CSF from ventricles to sinues?
A
Ventricles > Choroid plexus of 3rd ventricle > Subarachnoid space > Arachnoid villi > Sinuses
14
Q
What are the cerebral hmeispheres composed of?
A
- White matter - Myelinated fibers & their tracts, highways
- Cerebral cortex - Thin layer of superficial gray matter, cities
- Subcortical nuclei - Basal ganglia (PNS)/nuclei (CNS)
15
Q
What are the 3 types of White Matter fibers?
A
- Commissural fibers – connect gray matter of 2 hemispheres
- Association fibers – connect diff parts of same hemisphere
- Projection fibers – connect hemispheres w/ lower brain or spinal cord
16
Q
What are the main Functional Areas of Cerebral Cortex?
A
- Motor areas – control voluntary movement
- Sensory areas – conscious awareness of sensation
- Association areas – integrate diverse information
17
Q
Primary Motor Cortex
A
- Precentral gyri of frontal lobe contains pyramidal neurons
- Long axons form upper motor neuron corticospinal tracts
- Allows conscious control of precise, skilled, voluntary movements
- Somatotopic arrangement
18
Q
Premotor Cortex
A
- Anterior to precentral gyrus in frontal lobe
- Sends info to primary motor cortex to coordinate muscle groups for simultaneous or sequential actions
- Controls learned, repetitious, or patterned motor skills
- Involved in planning of movements that depend on sensory feedback
- Direct connection w/ corticospinal tract (15%)
19
Q
Broca’s Area
A
- Anterior to inferior region of premotor area in frontal lobe
- Present in 1 hemisphere (usually left)
- Motor speech area that directs tongue muscles
- Active as one prepares to speak
- Area in right hemisphere controls non-verbal communication
Left side – programs what you say
Right side – programs how you say it
20
Q
Frontal Eye Field
A
- Anterior to premotor cortex in frontal lobe, superior to Broca’s area
- Controls voluntary eye movements
21
Q
Primary Somatosensory Cortex
A
- In postcentral gyri of parietal lobe
- Receives sensory info from skin, skeletal muscles & joints
- Capable of spatial discrimination
22
Q
Somatosensory Association Cortex
A
- Posterior to primary somatosensory cortex
- Integrates sensory input from primary somatosensory cortex
- Determines size, texture & relationship of parts of objects being felt
23
Q
Primary Visual Cortex
A
- Extreme posterior tip of occipital lobe (most of it is buried medially in calcarine sulcus)
- Receives visual info from retinas
24
Q
Visual Association Area
A
- Surrounds primary visual cortex
- Uses past visual experiences to interpret visual stimuli (ex. Color, form & movement)
- Complex processing involves entire posterior ½ of cerebral hemispheres
25
Q
Primary Auditory Cortex
A
- Superior margin of temporal lobes
- Interprets info from inner ear as pitch, loudness & location
26
Q
Auditory Association Cortex
A
- Posterior to primary auditory cortex
- Stores memories of sounds & permits perception of sounds
27
Q
Olfactory Cortex
A
- Medial aspect of temporal lobes
- Conscious awareness of odors
28
Q
Gustatory Cortex
A
- In insula, deep to temporal lobe
- Involved in perception of taste
29
Q
Visceral Sensory Area
A
- Posterior to gustatory cortex
- Conscious perception of visceral sensations
30
Q
Multimodal Association Areas
A
- Receives input from multiple sensory areas; sends output to multiple areas
- Allow us to give meaning to info received, store it as memory, compare it to previous experience & decide on actions to take
- 3 parts:
- Anterior association area (aka prefrontal cortex)
- Posterior association area
- Limbic system (deep)
- Info > recognize what it is > do we need to do something
31
Q
Anterior Association Area
A
- In frontal lobe – just deep to forehead
- Most complicated cortical region (executive function)
- Involved w/ intellect, cognition, recall & personality
- Not fully developed until you’re 25
32
Q
Posterior Association Area
A
- Large region in temporal, parietal & occipital lobes
- Plays role in recognizing patterns, faces & localizing us in space
- Prosopagnosia, unilateral neglect
- Involved in understanding written & spoken language – Wernicke’s area
33
Q
Limbic Association Area
A
- Part of limbic system
- Provides emotional impact & helps establish memories
34
Q
Basal Nuclei
A
- Subcortical nuclei
- Consists of corpus striatum
- Caudate nucleus – next to lateral ventricle
- Lentiform nucleus
- Putamen – lateral cone
- Globus pallidus – medial
- Functionally associated w/ subthalamic nuclei (diencephalon) and substantia nigra (midbrain)
35
Q
What are the functions of basal nuclei?
A
- Influence muscular control
- Help regulate attention & cognition
- Regulate intensity of slow or stereotyped movements
- Inhibit antagonistic & unnecessary movements
36
Q
What makes up the Diencephalon?
A
- Hypothalamus
- Thalamus
- Epithalamus
- 3rd ventricle runs through
37
Q
Thalamus
A
- 80% of diencephalon
- Superolateral walls of 3rd ventricle
- Connected by interthalamic adhesion
- Contains several nuclei that project & receive fibers from cerebral cortex
- Relay station
38
Q
Hypothalamus
A
- Forms inferolateral walls of 3rd ventricle
- Contains many nuclei
- Mammillary bodies (memory, limbic & smell)
- Supraoptic & paraventricular nuclei – posterior pituitary
- Suprachiasmatic nucleus – pineal gland
39
Q
What are the functions of Hypothalamus
A
- Autonomic control center for many visceral functions
- Regulates body temp, food intake, water balance, & thirst
- Regulates sleep & sleep cycle
- Produces posterior pituitary hormones
- Controls release of hormones by anterior pituitary
- Center for emotional response – the 4 F’s
- Feeding
- Fearing
- Fighting
- Fornication
40
Q
Epithalamus
A
- Most posterior of diencephalon & roof of 3rd ventricle
- Pineal gland - secretes melatonin
- Pine cone shaped
41
Q
What parts make up the brain stem?
A
- midbrain
- pons
- medulla oblongata
42
Q
What are the stuctures on the Midbrain?
A
- Crus cerebri of cerebral peduncles - contain pyramidal motor tracts
- Superior colliculi (2) - visual reflex centers
- Interior colliculi (2) - auditory relay centers
- Substantia nigra - functionally linked to striatum (dopamine)
- So have dopaminergic inputs to nuclei
- Red nucleus - relay nuclei for some descending motor pathways & part of reticular formation
- Periaqueductal gray - suppresses pain
43
Q
What are the structures of Pons?
A
- Forms part of anterior wall of 4th ventricle
- Pyramidal tract - connects higher brain centers & spinal cord (motor)
- Some nuclei of reticular formation
- Nuclei that help maintain normal rhythm of breathing
44
Q
What are the Structures of Medulla Oblongata?
A
- Joins spinal cord at foramen magnum
- Forms part of ventral wall of 4th ventricle
- Pyramids - 2 ventral longitudinal ridges formed by pyramidal tracts (motor)
- Decussation of pyramids - crossover of corticospinal tracts
- Inferior olivary nuclei - relay sensory info form muscles & joints to cerebellum
- Several nuclei - nucleus cuneatus & nucleus gracilis
- Relay sensory info
45
Q
What are the Autonomic Reflex Centers in MO?
A
- Cardiovascular center:
○ Cardiac center - adjusts force & rate of heart contraction
○ Vasomotor center - adjusts blood vessel diameter for BP regulation
○ Both have influence blood pressure - Respiratory centers:
○ Generate respiratory rhythm
○ Control rate & depth of breathing - Additional centers regulate vomiting, hiccupping, swallowing, coughing, & sneezing
46
Q
What is the Cerebellum & its Functions?
A
- Posterior to pons & medulla
- Subconsciously provides precise timing & appropriate patterns of skeletal muscle contraction
- Ipsilateral to body
- Form coordinated movement
- Plays role in nonmotor functions such as word association & puzzle solving
47
Q
What are the Structures of Cerebellum?
A
- hemispheres connected by vermis
- Each hemisphere has 3 lobes
○ Anterior
○ Posterior
○ Flocculonodular (vesibular) - Folia - transversely oriented gyri of gray matter making up cerebellar cortex
○ Contains Perkinjee cells
○ Arbor vitae - distinctive treelike pattern of cerebellar white matter - 3 paired fiber tracts connect cerebellum to brain stem
○ Superior cerebellar peduncles - connect cerebellum to midbrain (sup.)
○ Middle cerebellar peduncles - connect pons to cerebellum
○Inferior cerebellar peduncles - connect medulla & cerebellum (inf.)
47
Q
What areas of Cerebrum does Middle Cerebral Artery Supply?
A
- face & head
- Broca Area
- Wernicke’s area
- Visual cortex
- Auditory area
- motor & sensory for hip, trunk, arm, hands, fingers, thumb, face, lips, tongue, mouth
- Language comprehensions
- Reading & writing
47
Q
What areas of cerebrum does Anterior Cerebral Arteries supply?
A
- prefrontal cortex - working memory, exectuvie functions, complex problem solving
- supplementary motor area
- Motor Area for foot, leg, and urinary bladder
- somatic sensory - sensory area for foot & leg
48
Q
What areas of cerebrum does Posterior Cerebral Arteries supply?
A
- Visual cortex w/ striate along calcarine sulcus
- primary visual cortex & visual association area
48
Q
What are Functional Brain systems?
Definition
A
- Networks of neurons that work together & span wide areas of brain
48
Q
What are examples of Functional brain systems
A
- Limbic system
- Reticular formation
- Direct & indirect pathways of the basal nuclei
48
Q
What is the Limbic System? Parts?
A
- Structures from medial cerebral hemispheres & diencephalon
- Cerebral structures encircle superior brainstem
- Establish emotional states
- Linking conscious, intellectual functions of cerebral cortex w/ unconscious & autonomic functions of brain stem
- Facilitating memory storage & retrieval
- Amygdala, Cingulate Gyrus, Hippocampus
48
Q
Amygdala
A
- Almond-shaped nucleus anterior to tail of caudate deep in medial temporal lobes
- Critical for responding to perceived threats
- Required for emotional memory
48
Q
Cingulate Gyrus
A
- Located along medial aspect of cerebral hemispheres next to corpus callosum
- Plays a role in responding to perceived threats, expressing emotions vis gestures & resolves mental conflict when frustrated
49
Q
Hippocampus
A
- Looks like sea horse
- Located in medial temporal lobe
- Connected to mammillary bodies of hypothalamus through white matter (fornix)
- Plays role in learning, memory & emotion
49
Q
Reticular Activating System
A
- Sends impulses to cerebral cortex to keep it conscious & alert & enhancing its excitability
- Filters out repetitive & weak stimuli (99%)
- Inhibited by sleep centers of hypothalamus & other neural regions
○ Depressed by alcohol, sleep inducing drugs & tranquilizers - Severe injury results in permanent unconsciousness
49
Q
What is the Reticular Formation?
A
- 3 broad columns along length of brain stem
- Has far-flung axonal connections w/ hypothalamus, thalamus, cerebral cortex, cerebellum & spinal cord
- Regulate visceral motor functions (vasomotor, cardiac & respiratory centers)
- Helps control coarse limb movements
Not specific, coordinated movements
49
Q
What is Consciousness & the continuum?
A
- Simultaneous activity of large areas of the cerebral cortex
- Conscious perception of sensation
- Voluntary initiation & control of movement
- Capabilities associated w/ higher mental processing (memory, logic, judgment etc..)
- Alertness
- Drowsiness (lethargy) -> sleep
- Stupor
- Coma
50
Q
What occurs during sleep?
A
- State of partial unconsciousness from which a person can be aroused by stimulation
- Alternating cycles of sleep & wakefulness reflect a natural circadian rhythm
- RAS activity is inhibited during sleep
- Suprachiasmatic & preoptic nuclei of hypothalamus time sleep cycle
- Releases peptide orexins which activate reticular formation (wake-up chemical)
- Nonrapid eye movement (NREM)
- Rapid eye movement (REM)
51
Q
What is the Importance of Sleep?
A
- Slow-wave sleep (NREM stages 3 & 4) is restorative stage
- deprived of REM sleep become moody & depressed & exhibit various personality disorders
- REM sleep may be a reverse learning process
- enhances immune system - sleep-inducing factors include interlukin-1, interferon, serotonin & tumor necrosis factor
52
Q
What are the 2 stages of Memory?
A
- Short-term memory (STM or working memory)
- Temporary holding of info, limited to 7-8 pieces of info
- Long-term memory (LTM) has limitless capacity
- Can have some info go directly to long term memory
53
Q
What factors affect transfer from STM to LTM?
A
- Emotional state - best if alert, motivated, surprised, & aroused
- Rehearsal - repetition & practice
- Association - tying new info w/ old memories
- Automatic memory - subconscious info stored in LTM
54
Q
What occurs on a Molecular Level for Memory?
A
- Altered mRNA is synthesized & moved to axons & dendrites
- Dendritic spines change shape
- Extracellular proteins are deposited at synapses involved in LTM
- Number & size of presynaptic terminals may increase
- More neurotransmitter is released by presynaptic neurons
55
Q
What is Declarative Memory
A
- Related to conscious thoughts & language ability
- Stored in LTM w/ context in which it was learned
- Hippocampus & surrounding temporal lobes function in consolidation & access to memory
- Ach from basal forebrain is necessary for memory formation & retrieval
55
Q
What is Nondeclarative Memory
A
- Less conscious or unconscious
- Acquired through experience & repetition (best remembered by doing, hard to unlearn)
- Emotional memory - Amygdala
- Motor memory - Cerebellum
- Procedural memory - basal nuclei relay sensory info & motor inputs to thalamus & premotor cortex
- Dopamine
56
Q
When excitatory neuron fires a lot…
A
postsynaptic neuron will fire alot
57
Q
When excitatory neuron fires a little…
A
Postsynaptic neuron fires a little
58
Q
When inhibitory neuron fires a lot…
A
postsynaptic neuron fires a little
59
Q
When inhibitory neuron fires a little…
A
Postsynaptic neuron fires a lot
60
Q
Effect of dopamine direct vs. indirect
A
Direct circuit is excited by SNpc dopamine input while indirect circuit is inhibited by SNpc dopamine
61
Q
Effect of thalamic input to cortex - direct vs indirect
A
- direct - increase excitatory thalamic input to cortex
- indirect - decrease excitatory thalamic input to cortex
62
Q
Effect on motor activity - direct vs. indirect
A
- direct - turns UP motor activity
- indirect - turns down motor activity
63
Q
Where does the spinal cord begin and end?
A
- Begins at foramen magnum
- Ends as conus medullaris at L1
64
Q
How many spinal nerves are there?
A
- 31 pairs
- 8 cervical spinal nerves
- C1 - C7 exit above vertebrae of same #1
- 12 thoracic spinal nerves
- 5 lumbar spinal nerves
- 5 sacral spinal nerves
- 1 Coccygeal
- All other exit below vertebrae of same #
65
Q
What are the functions of the spinal cord?
A
- Provides 2-way communication to & from brain
- Brain talks to body & body talks to brain
- Contains spinal reflex centers
66
Q
What protection does the Spinal Cord have?
A
- Bone, meninges, & CSF (in subarachnoid space)
- Cushion of fat & network of veins in epidural space
- Denticulate ligaments - lateral extensions of pia mater that secure cord to dura mater
- Dural & arachnoid mater extend to S2
- Cauda equina
- Filum terminale
67
Q
Parts of Gray Matter in Spinal Cord
A
- Ventral horns - somatic motor neurons
○ Ventral = motor - Lateral horns - only in thoracic & lumbar regions, sympathetic neurons
- Only found T1-L2
- Dorsal horns - interneurons receiving somatic & visceral sensory input
○ Dorsal = sensory - Dorsal root ganglia - cell bodies of sensory neurons
68
Q
Parts of White Matter in Spinal Cord
A
- Spinal tract = collections of axons w/ similar functions
- Consists of bilateral tracts in 3 white columns (funiculi)
- Ascending/sensory tracts - dorsal, lateral + ventral columns
- Descending/motor tracts - lateral + central columns
- Transverse tracts (commissural fibers) cross from one side to other
69
Q
What are the Ascending Pathways?
A
- Dorsal column-medial lemniscal pathways (DCML) - thalamus
- Spinothalamic pathways (anterolateral pathway) - thalamus
- spinocerebellar tracts - terminate in cerebellum
70
Q
Dorsal Column-Medial Lemniscal (DCML) Pathaways
A
- discriminative touch & vibrations
- sensory ascedning pathway
- ascends same side of body which it enters
- crosses over in medulla
- 2nd neuron enters thalamus
- 3rd neuron to somatosensory cortex
71
Q
Lateral Spinothalamic tract
A
- pain & temperature impulses
- sensory ascending tract
- 1st neuron in DRG, synapses & crosses over in dorsal horn where it enters
- 2nd neuron ascends opposite side to thalamus
- 3rd neuron to primary somatosensory cortex
72
Q
Spinocerebellar tract
A
- subconscious proprioceptive info from trunk & lower limb to cerebellum
- ONLY 2 NEURONS
- doesn’t go to thalamus, goes to cerebellum
- ipsilateral projections
73
Q
What are the Descending Pathways?
A
- Direct - corticospinal/pyramidal tract
- Indirect - all the other ones
NOTE: Involve 2 neurons:
* Upper motor neurons - cortex to spinal cord
* Lower motor neurons - spinal cord to skeletal muscle (ventral horn motor neurons)
74
Q
Direct (corticospinal) Tract
A
- Impulses from pyramidal neurons in precentral gyri (primary motor cortex)pass through pyramidal tracts (upper motor neurons)
- crossing over at medulla
- Axons synapse w/ interneurons or ventral horn motor neurons (lower motor neurons)
Regulates fast & fine (skilled) movement
75
Q
Indirect (Extrapyramidal) system
A
- Pathways are complex & multisynaptic
- Tectospinal tract - mediate head movements in response to visual stimuli (contralateral)
- Vestibulospinal tract - maintain balance during standing & moving (ipsilateral)
- Corticobulbar tract - motor to skeletal muscle of cranial nerves (both contralateral & ipsilateral)
