Central Nervous System Flashcards
What are the 5 paired lobes of the Cerebrum
Frontal lobe
Pariteal lobe
Occipital lobe
Temporal lobe
Gyri of insula (deep lobe pulling back temporal lobe)
What are the 4 parts of the adult brain
Cerebral hemisphere
Diencephalon
Brain Stem
Cerebellum
What are the cerebral hemisphere markings and their meanings (3)
Fissures: deep grooves
Sulcus: shallow grooves
Gyrus: ridges or bumps
What does the central sulcus seperate
Separates frontal & parietal
What do the lateral sulcus separate
Separates temporal from frontal/parietal
What do the transverse cerebral fissure separate
Separates cerebrum from cerebellum
What does the longitudinal fissure separate
separates left & right cerebral hemispheres
What does the calcarine sulcus separate
separates primary visual cortex
What is the order that protects the brain
- SCALP
- skull
- Blood-brain barrier
- Meninges
- CSF
What does SCALP stand for
Skin
Connective tissue (dense)
Aponeurotic layer
Loose connective tissue
Pericranium
What is the role the blood-brain barrier
- Physically separates neurons from certain bloodborne substances
- Acts as a metabolic barrier
What is the composition of the blood brain-barrier (from most deep to superficial). What is the role of astrocyte feet in this? What do they allow in?
Endothelial cells (simple squamous)
- Have tight junctions between them that allow lipid soluble molecules in
Basement membrane
Pericytes: (supporting cells)
Astrocyte feet:
- Induce formation of tight junctions
- insulate to change permeability of capilleries
What do receptor mediated and adsorptive transcytosis transport in blood brain barrier?
What is the main note for transport?
Receptor: insulin, transferrin, antidbodies
Adsorptive: albumin, cationized proteins
Drugs must be not bound to plasma protein
What does dura mater form when separated
Superior sagittal sinus
What is the meningeal layer of dura mater. What does it separate?
Falx cerebri in longitudinal fissure
What are the 2 layers in dura mater
Periosteal layer
Meningeal layer
What is arachnoid mater and dura mater separated by?
Subdural space (potential space)
What does subarachnoid space contain
CSF + blood vessels
What does the arachnoid villi help with
1 way valve that allows CSF to move from subarachnoid space to superior sagittal sinus
What is the role of pia mater
all the bumps & grooves of the brain
softest meninges
where is the location of the meningeal arteries that supply blood to dura mater
Epidural space (potential space)
What are some functions of the CSF (4)
- Gives buoyancy to brain
- Protects CNS from blows & trauma
- Nourishes brain & carries chemical signals
- Clears wastes
What is the blood filtrate produced by. Where is it located. How much does it produce a day? What is it’s constant volume
Produced by: Choroid Plexus
Location: ventricles + subarachnoid space
Produces: 500mL/day
Constant volume: 125-150mL
How does the CSF filter?
It absorbs wastes and unnecessary solutes (goes in)
It filters glucose, vitamins, and small ions (goes out)
What cells lines CSF. What type are they
Ependymal cells
Simple cuboidal/columnar
What is dorsal and ventral direction interchangeable with?
Dorsal (superior)
Ventral (inferior)
Name the 5 ventricles in order from dorsal-ventral (superior - inferior).
Name their location as well
Lateral ventricles (cerebral hemispheres)
Interventicular foramen (foramen of monro)
Third ventricle (in diencephalon)
Cerebral aqueduct (connects the 3rd and 4th ventricle via midbrain)
Fourth ventricle (pons, medulla, cerebellum)
Where does the sigmoid sinus lead to?
Internal jugular vein
What are the dural venous sinuses (5)
Superior sagittal sinus
Inferior sagittal sinus
Straight sinus
Transverse sinus
Sigmoid sinus
What are cerebral hemispheres composed of broadly
White matter
cerebral cortex
Subcortical nuclei
What is the cerebral white matter fibres composed of and what do they connect/communicate to
CAP
Commissural fibers: connect gray matter of 2 hemispheres
Association fibers: connect different parts of the same hemisphere
Projection fibers: connect hemispheres with lower brain or spinal cord
What does conscious behaviour involve
the entire cerebral cortex
Which cortex is involved in the motor areas (4)
Primary motor cortex
Premotor cortex
Broca’s area
Frontal eye field
What/where contains the primary motor cortex?
What is the associated movement?
PREcentral gyrus
Conscious control of precise, skilled, voluntary movements
Where is the premotor cortex.
What is the associated motor skill?
Anterior to PREcentral gyrus
Controls learned, repititous, or patterned motor skills
Where is the Broca’s Area?
What is the associated motor skill?
Anterior to inferior region of premotor area in frontal lobe
Motor speech that directs tongue muscles
Where is the frontal eye field?
What is the associated motor skill?
Anterior to premotor cortex
Controls voluntary eye movements
What does the sensory area do and what is involved
Conscious awareness of sensation
Involves somatic sensation, taste, vision, hearing
Where is the primary somatosensory cortex
What information does it recieve
POSTcentral gyri
receives sensory information from skin, muscles, joints
What is the role of the somatosensory association cortex
Integrates sensory input from primary somatosensory cortex
Determines size, texture, & relationship of parts of object being felt
(determines what is touching you)
Where is the primary visual cortex
Posterior, Occipital lobe
in calcarine sulcus
Where is the visual association area
What is its role for the 2 pathways
surrounds primary visual cortex
2 streams
Dorsal stream: “where” pathway
Ventral stream: “what” pathway
Where are the auditory areas and what is the role of the primary auditory cortex and auditory association area
Temporal lobes
primary auditory cortex
- interprets info as pitch, loudness, and location
auditory association area
- allows for perception of sounds, memories of sounds
Where and what is the role of the olfactory cortex
Temporal lobe
Awareness of odours
What part of the brain is involed with taste
Gustatory cortex
What are the steps in in the multimodal association areas
What is the roles of these areas
Sensory receptors –> Primary sensory cortex –> sensory association cortex –> multimodal association cortex
Role:
1. give meaning to information received
2. store it as memory
3. Compare it to previous experience
4. Decide on what action to take
What are 3 parts associated with the multimodal assocation areas
Anterior Association area (prefrontal cortex)
Posterior association area
Limbic system
What is the role of the prefrontal cortex
Intellect
personality
judgement
What is the role of the posterior association area
recognizing patters, faces, and localizing us in space
What area of the brain is associated with understanding written & spoken language
Where is it
Wernicke’s area
Posterior Association Area
What is the role of broca’s area and motor cortex with the wernickes area
Broca’s area
forming the motor pattern of tongue
Motor cortex
develops muscle to speak the word
Which part plays a role in emotion. ex. perceived threats, resolving mental conflicts when mad
Where is it?
Cingulate gyrus
In the limbic association area
What does basal nuclei consist of?
What type of nuclei are associated with it?
Corpus striatum (striped gray/white bdoy)
Caudate nucleus
Lentiform nucleus
What are associated with lentiform nucleus. Where are they in reference to each other
Putamen (external)
globus pallidus (internal/tip)
What are the functions of basal nuclei
Allows motor patterns to be smooth
Where are the diencephalon and what are associated with it
Encloses 3rd ventricle
Thalamus
Hypothalamus
Epithalamus
What is the role of thalamus
Relay information
What are the medial and lateral geniculate body used for in the thalamus
Medial: auditory
Lateral: visual
What is the role of the infundibulum
stack connecting hypothalamus to pituitary gland
What are the roles of the mammillary bodies
memory, limbic (emotion) & smell
What are the nuclei associated with the hypothalamus and their roles
Mammillary bodies (memory, limbic & smell)
Supraoptic & paraventicular nuclei (produces posterior pituitary hormones)
Suprachaismatic nucleus (pineal gland) (regulates sleep)
What are the functions of the hypothalamus
Center for emotional response (4Fs):
Feeding
Fearing
Fighting
Fornication
Autonomic control centre for many visceral (organ) functions
What is associated with the epithalamus.
What is its role
Pineal gland
secretes melatonin
What is the main function of the brain stem.
What ventricle is it part of
controls automatic behaviours necessary for survival
Cerebral aqueduct
What do the crus cerebri of cerebral peduncles contain (brain foot)
contain pyramidal motor tracts
What are associated with the corpora quadrigemina.?
What are their roles?
Superior colliculi (visual reflex)
Inferior colliculi (auditory relay)
What is the role of substantia nigra
dopamine (striatum)
What is the role of red nucleus
relay nuclei for some descending motor pathways & part of reticular formation
What surpresses pain
periaqueductal gray
Which ventricle is associated with the pons
What is the function of the pons
4th ventricle
Normal rhythm of breathing
What connects the higher brain centres & spinal cord for a motor pathway
pyramidal tract
What is the main nuclei in the medulla oblongata and what is its function
Inferior olivary nuclei
- relay sensory information from muscles & joints to cerebellum
What is the function of the medulla oblongata for cardiovascular and respiratory centres
Automatic reflex centre (involuntary)
Cardiovascular:
- adjust heart rate
- Vasomotor centre: adjust blood vessel diameter
Respiratory Centres
- generate respiratory rhythm
- control rate and depth of breathing
Additionally: vomiting, hiccuping, swallowing, coughing & sneezing
What is the function of the cerebellum
Subconsciously provides precise movements for the skeletal muscle
also plays a role in word association & puzzle solving
What are the 2 hemispheres of the cerebellum connected by?
Vermis
What are the 3 lobes of the cerbellum
Anterior
Posterior
Flocculonodular
What is the anatomy of the cerebellum
Folia: transversely oriented gyri of GRAY matter
Arbor vitae: distinctive treelike pattern of WHITE matter
What are the 3 paired fiber tracts that connect cerebellum to brain stem?
What parts specifically connects to cerebellum?
Superior cerebella peduncles: Midbrain
Middle cerebellar peduncles: pons
Inferior cerebellar peduncles: medulle
What are the relatioships between blood supply & cortex function (name the 3 arteries and its relationship)
Anterior cerebral artery: body/feet motor
Middle cerebral artery: anything face/hand motor
Posterior cerebral artery:
Vision
What are the general functions of the limbic system
- Establish emotional states
- Linking conscious with unconscious functions
- Facilitating memory storage & retrieval
What does amygdala play a role in
emotion + memory
What does hippocampus play a role in
learning and memory
Which lobes do the limbic system interact with?
For what purpose?
Prefrontal lobes
For emotion & cognition
What is the role of the reticular formation
Regulate visceral motor functions
What is the role of the reticular activating system?
Keeps important things conscious
What part of the brain times your sleep cycle
What chemical is released to wake up
hypothalamus
Orexins
Which part of sleep is associated with dreaming
Rapid-eye-movement
What are the 4 factors of transfer from STM to LTM
- Emotional state
- Rehearsal
- Association
- Automatic memory
What occurs molecularly during learning
-mRNA is changed & 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
In declarative memory for conscious thoughts,
What part functions for consolidation & access to memory?
What is necessary for memory formation & retrieval?
Hippocampus & surrounding temporal lobes
ACh from basal forebrain
In non declarative memory for unconscious thoughts,
What occurs for procedural memory? What is necessary in this process
Basal nuclei relay sensory & motor inputs to thalamus & premotor cortex
Dopamine from substantia nigra is necessary
What is the effect in motor activity of direct and indirect pathway (up/down)
What is the effect in dopamine to the both pathways? (excites/inhibits)
Direct:
Turns UP motor activity
Dopamine EXCITES pathway to increase thalamic output to cortex (motor)
Indirect
Turns DOWN motor activity
Dopamine INHIBITS pathway to increase thalamic output to cortex (motor)
What type (excitatory/inhibitory) does each part of the brain have?
What do each release?
Cerebral cortex
Lentiform nuclei (putamen, GPE, GPI)
Thalamus
Subthalamic nuceli
Substantia Nigra
Excitatory: release Glu
Inhibitory: release GABA
Cerebral cortex EXCITATORY
Lentiform nuclei (putamen, GPE, GPI) INHIBITORY
Thalamus EXCITATORY
Subthalamic nuceli EXCITATORY
Substantia Nigra BOTH
Where does the spinal cord begin and end?
Begin: Foramen magnum
End: Conus medullaris
What is the role of denticulate ligaments in the spinal cord?
What is the difference in dura mater between brain & spinal?
They are lateral extensions of pia mater that secure cord to dura mater
Dura mater is not fused into the bone in the spinal cord
Where is the cauda equina?
A collection of nerve roots in subarachnoid space
What regions of the spinal cord are lateral horns found
Only in thoracic & lumbar regions
T1-L2
What are the ascending pathways for? descending?
Ascending: sensory
Descending: motor
What is the big picture for first, second, and third order neuron in an ascending pathway
Third order:
- Synapse/cell body in thalamus
- Extend to somatosensory cortex
Second-order neuron
- cell body in dorsal horn
- Extend to thalamus or cerebellum
First order:
- Conduct impulses from cutaneous receptors & proprioceptors (spatial recognition)
- Goes until spinal cord or medulla
Explain the Dorsal-column Medial Lemniscal pathway (DCML)
What are involved? Where is the cross over?
It is for touch & vibrations
Thalamus to primary somatosensory cortex
Axons extend to thalamus
Crossover at internal arcuate fibres (medulla)
Fasciculus Gracilis
Fasciculus cuneatus
Explain the Lateral spinothalamic tract?
What are involved? Where is the cross over?
Pain & temperature
Thalamus to primary somatosensory cortex
Axon extend to thalamus
Crossover at level of entry
muscle receptor enters dorsal root
Explain the Spinocerebellar tract
What are involved?
subconscious proprioceptive (helps with balance)
Dorsal horn to cerebellum
Lower trunk Muscle to dorsal root
What neurons are involved in descending pathways
Upper motor neurons: cortex to spinal cord
Lower motor neurons: spinal cord to skeletal muscle
Describe both direct pathways for ventral and lateral corticospinal tract
-Regulates fast & fine skilled movements
-Starts at pyramidal cells and goes down the internal capsule and cerebral peduncle
-Both synapse at the level at which it EXITS
Ventral corticospinal tract:
Upper motor neurons: pyramid cells to lumbar spinal cord
Lower motor neuron: ventral horn synapse and exits at ventral root
Lateral corticospinal tract:
Upper motor neurons: pyramid cells to lumbar spinal cord
Crossover of pyramids
Lower motor neuron: ventral horn synapse and exits at ventral root
For an indirect descending system
Which tract corresponds with the following:
Mediate head movements in response to visual stimuli
Maintain balance during standing & moving
Motor to skeletal muscle of cranial nerves
Tectospinal tract
Vestibulospinal tract
Corticobulbar tract
What are the levels of motor control from highest to lowest? What brain parts are involved? What do they do?
Precommand level (highest)
- cerebellum and basal nuclei
- programs and instrunctions
Projection level (middle)
- Motor cortex (pyrimidal pathways) and brain stem nuclei
- conveys instructions to spinal cord motor neurons and sends a copy of info to higher levels
Segmental level (lowest)
- Spinal cord
- Contains central pattern generators
