Topic 19: Nervous System Flashcards
what are the 2 divisions of the nervous system?
-central nervous system (CNS)
-peripheral nervous system (PNS)
what is the central nervous system?
-command center
-brain + spinal cord
-processes + integrates info
what does the peripheral nervous system consist of?
-cranial nerves
-spinal nerves
where do the cranial nerves go?
-to/from the brain
where do the spinal nerves go?
-to/from the spinal cord
what are the 2 divisions of the PNS?
-sensory/afferent division
-motor/efferent division
what is the sensory/afferent division of the PNS?
-arriving/going in to the CNS
-has sensory receptors that detect stimuli
-stimuli = changes in the internal/external environments
what is the motor/efferent division of the PNS?
-exiting/going out of the CNS
-nerves convey impulses away from the CNS
-innervates (supplies nerves to) effectors
what are effectors?
-muscles
-glands (exocrine or endocrine)
what are the 2 cells in the nervous system?
-neurons
-neuroglia (glial cells)
what are neurons?
-cells that conduct impulses
-make up the CNS + PNS
-mostly amitotic (irreplaceable)
what is the structure of a neuron?
-cell body
-cell body processes (dendrites + axon)
-can be very long, but are very small in diameter
which neurons are able to be replaced?
-taste
-olfaction
-memory
what are the characteristics of the cell body of a neuron?
-contain typical organelles
-rough ER is called nissl bodies
-clusters of cell bodies in the CNS = nuclei (gray matter)
-clusters of cell bodies in the PNS = ganglia
what is the purpose of dendrites?
-receive incoming messages and relay them to the cell body
what is the purpose of the axon?
-carry impulses away from the cell body
what are the parts of an axon?
-axon hillock
-axon terminal
what is the axon hillock?
-where the axon meets the cell body
what is the axon terminal?
-typically branched with synaptic end bulbs (enlarged tips)
-at the end of the axon
what can change between axons?
-can be myelinated or unmyelinated
what does it mean for an axon to be myelinated?
-wrapped in many layers of cell membrane (myelin sheath)
-gives support
-gives electrical insulation (increases signal speed)
what are gaps in the myelin sheath called?
-nodes of ranvier (very small)
what are the cells that make up the myelin sheath in the CNS? PNS?
-oligodendrocytes (CNS)
-schwann cells (PNS)
where are there myelinated axon bundles?
-CNS = tracts (white matter)
-PNS = nerves
what are unmyelinated neurons?
-no myelin sheath
what are neuroglia (glial cells)?
-support neuron cells
-can undergo mitosis to be replaced
-prone to cancer/brain tumors
what are the 2 types of neuroglia (glial cells)?
-CNS neuroglia
-PNS neuroglia
what are the glial cells of the CNS?
-oligodendrocytes
-microglia
-astrocytes
-ependymal (neural epithelia)
what is the purpose of oligodendrocytes?
-produce myelin around the axon in the CNS
what is the purpose/function of microglia?
-protective
-become phagocytic if infected, dead or damaged neurons are detected
-because immune cells cannot enter the CNS
what is the purpose of astrocytes?
-surround blood capillaries to form part of the blood brain barrier (BBB)
-control capillary permeability of what is leaving + going to the brain
what is the purpose of ependymal (neural epithelia)?
-line brain ventricles + central canal of the spinal cord
-secrete cerebrospinal fluid (CSF) + circulate it (cillia)
what are the glial cells of the PNS?
-schwann cells
-satellite cells
what is the purpose of schwann cells?
-form myelin around axons in the PNS
what is the purpose of satellite cells?
-surround neuron cell bodies in ganglia
-protect + support
what are the structural types of neurons? what are they based on?
-unipolar
-bipolar
-multipolar
-based on the # of cell processes off of the cell body
what are unipolar neurons?
-1 process that divides into 2 (central and peripheral portions)
-peripheral end has dendrites (interact with sensory receptors for pain, touch, etc)
-remainder is the axon
-always sensory neurons
what are bipolar neurons?
-2 processes
-1 axon, 1 process with dendrites
-sensory (retina + nose (olfaction) )
what are multipolar neurons?
-3 or more processes
-1 axon + many dendrites
-all interneurons + motor neurons
-most common
what are the 3 functional types of neurons?
-sensory/afferent neurons
-interneurons
-motor/efferent neurons
-based on the direction of impulse conduction
what are sensory/afferent neurons?
-mostly unipolar
-impulses from sensory receptors to the CNS
what are interneurons?
-within the CNS
-impulses between sensory + motor neurons
-99% of neurons
-mostly multipolar
what are motor/efferent neurons?
-impulses from CNS to effectors
-all multipolar
what are the different neuron junctions?
-neuronal junction
-neuromuscular junction
-neuroglandular junction
what are neuronal junctions?
-neuron to neuron
-can be chemical (use neurotransmitters)
-can be electrical (use ions)
what are neuromuscular junctions?
-motor neuron to skeletal muscle
what are neuroglandular junctions?
-motor neuron to gland
what are the most common neuronal synapses?
-chemical neuronal synapses
what is the structure of a chemical neuronal synapse?
-presynaptic neuron
-axon terminal
-synaptic cleft
-postsynaptic neuron
what is the presynaptic neuron?
-neuron bringing the impulse
what is the purpose of the axon terminal in chemical synapses?
-the synaptic end bulbs (presynaptic membrane) has synaptic vesicles inside
-synaptic vesicles contain a neurotransmitter that will be diffused through the synaptic cleft to the postsynaptic neuron
what is the synaptic cleft?
-space between neurons
what is the postsynaptic neuron?
-receives the impulse
-has a postsynaptic membrane (cell membrane of dendrites or a cell body with receptor sites for the neurotransmitter)
what are the protective features of the central nervous system?
-bone
-meninges
-cerebrospinal fluid (CSF)
-blood brain barrier
-cerebral arterial circle
what is the bone that protects the CNS?
-the skull + vertebral column
what are meninges?
-CT around the brain + spinal cord
-3 layers
what are the layers of meninges?
-dura mater (outer)
-arachnoid mater (middle)
-pia mater (inner)
what are the characteristics of the dura mater in the brain?
-2 fused layers
-separated in spots to form spaces = venous (dural) sinuses (brain only)
-these sinuses contain blood
what is deep to the dura mater for both the brain + the spinal cord?
-subdural space
-filled with ISF
what are the characteristics of the dura mater in the spinal cord?
-1 layer
-superficial to the dura mater is the epidural space (spinal cord only)
-space is filled with fat, blood vessels, CT, etc (spinal cord only)
what are the characteristics of the arachnoid mater in the brain?
-avascular
-subarachnoid space (deep)
-has arachnoid granulations (brain only)
what are the characteristics of the arachnoid mater in the spinal cord?
-avascular
-subarachnoid space (deep)
what is the subarachnoid space?
-contains cerebrospinal fluid (CSF)
-web like strands of CT to secure it to the pia mater below
what are arachnoid granulations?
-project into the dural sinuses
-cerebrospinal fluid (CSF) enters the granulations to return to the blood (in the sinuses)
what are the characteristics of the pia mater in the brain and spinal cord?
-on the surface of the CNS
-vascular
what is meningitis?
-inflammation of meninges
what is cerebrospinal fluid (CSF)
-surrounds the brain + spinal cord
-in the brain ventricles + central canal of spinal cord
-cushions the CNS (brain buoyant)
what forms and produces cerebrospinal fluid (CSF)?
-formed from blood plasma (similar composition)
-produced by choroid plexuses (networks) (blood capillaries) found in each ventricle
what are the brain ventricles?
-spaces inside the brain (filled with CSF)
-2 lateral ventricles (1st + 2nd) (in cerebrum)
-3rd ventricle (in diencephalon)
-4th ventricle (surrounded by pons, medulla oblongata, cerebrum)
what is the central canal of the spinal cord?
-space in the spinal cord
what cells make the blood brain barrier? how do they do so?
-endothelial cells (of capillaries) with tight junctions
-astrocytes (foot processes wrap around the endothelial cells)
how does the blood brain barrier let stuff through?
-selectively permeable
-allows glucose + fat soluble material
-does not allow toxins, antibiotics, etc
what is the cerebral arterial circle?
-cerebral arteries form a circle at the base of the forebrain
what structures does the cerebral arterial circle circle?
-pituitary gland
-optic chiasma (where optic nerves cross)
what does the cerebral arterial circle unite?
-unites the two major blood supplies to the brain (anterior + posterior)
what does the cerebral arterial circle provide?
-an alternate route for blood if the vessels are blocked
what is the cerebrum?
-part of the forebrain
-has right + left cerebral hemispheres
-contains different lobes and surface features
-has 3 layers
what are the lobes of the cerebrum? how are they named?
-frontal
-temporal
-parietal
-occipital
-insula (deep to the temporal lobe)
-named after the cranial bones (overlying)
what are the surface features of the cerebrum?
-fissures (deep grooves)
-gyri (ridges)
-sulci (shallow grooves)
what are the 3 fissures of the cerebrum?
-longitudinal fissure
-transverse fissure
-lateral fissure
what do each of the fissures separate?
-long. = right + left cerebral hemispheres
-trans. = cerebellum + cerebrum
-lat. = temporal lobe from the rest of the cerebrum
what are two examples of gyri in the cerebrum?
-postcentral gyrus in the parietal lobe
-precentral gyrus in the frontal lobe
what separates gyri?
-sulci
what is an example of a sulci in the cerebrum?
-central sulcus between frontal + parietal lobes
what are the 3 layers of the cerebrum?
-cerebral cortex
-tracts
-basal nuclei
what is the cerebral cortex layer of the cerebrum?
-2-4mm thick
-gray matter
-has functional areas
what are the functional areas of the cerebral cortex?
-motor areas
-sensory areas
-association areas
-other
what are the characteristics of the motor areas in the cerebral cortex?
-all in the frontal lobe
-control skeletal muscle movement
-3 regions
what are the 3 regions of motor areas in the cerebral cortex?
-primary motor area (precentral gyrus)
-premotor area
-broca’s area (motor speech)
what are the sensory areas in the cerebral cortex?
-general sensory area (pain, touch, temp, pressure)
-vision
-auditory + olfaction
-taste + visceral sensation
where is the general sensory area?
-postcentral gyrus in the parietal lobe
where is the vision sensory area?
-occipital lobe
where is the auditory + olfaction sensory area?
-temporal lobe
where is the taste + visceral sensation sensory area? what is an example of a visceral sensation?
-insula
-full bladder (feeling of internal organs)
what are association areas in the cerebral cortex? where are they?
-recognize info from memories
-parietal, occipital, temporal lobes
what are other sensory areas in the cerebral cortex? where are they?
-memory = temporal lobes
-conscious intellect (personality, learning, ideas, judgement, etc) = prefrontal cortex
what are tracts in the cerebrum?
-white matter
-3 types
what are the 3 types of tracts in the cerebrum?
-association tracts
-commissural tracts
-projection tracts
where do association tracts run from?
-gyrus to gyrus in the same hemisphere
where do commissural tracts run from? what is an example?
-gyrus to gyrus in opposite hemispheres
-ex: corpus callosum
where do projection tracts run from?
-vertically
-brain to spinal cord/spinal cord to brain
what are basal nuclei? what do they control?
-paired masses of gray matter (within white matter)
-control skeletal muscle movement
what is contained in the diencephalon of the brain?
-thalamus
-hypothalamus
-all gray matter
what is the thalamus?
-2 lobes connected by an intermediate mass (bridge through the 3rd ventricle)
-relay station for impulses coming to the cortex from the spinal cord
what is the hypothalamus?
-major regulator of the internal environment (visceral control) ex: blood pressure or heart rate
-inferior to thalamus, above the pituitary gland
what does the midbrain connect? what does it contain?
-connects pons + diencephalon
-contains cerebral aqueduct
what are contained in the anterior + posterior portions of the midbrain?
-anterior = cerebral peduncles (projection tracts)
-posterior = 4 nuclei (corpora quadrigemina)
what are the 4 nuclei of the midbrain posterior portion? what is their purpose?
-2 superior colliculi (visual reflexes)
-2 inferior colliculi (hearing)
what are the parts within the hindbrain?
-pons
-medulla
-cerebellum
what is the pons of the hindbrain?
-tracts between the brain + spinal cord
-tracts to/from the cerebellum
-pontine respiratory centers
-anterior to the cerebellum
what is the medulla of the hindbrain?
-2 bulges (called pyramids)
-3 vital centers
-several non vital centers
-inferior to the pons
-ends at the foramen magnum
what occurs just above the spinal cord?
-decussation (crossover) of pyramids
what are the 3 vital centers in the medulla?
-cardiac
-vasomotor (blood vessels)
-respiratory
what are the non-vital centers in the medulla?
-swallowing
-sneezing
-vomiting
what forms the brain stem?
-midbrain
-pons
-medulla
what is the cerebellum?
-has folds similar to gyri called folia
-cortex is grey matter
-arbor vitae (deep to cortex) is white matter
-coordinates skeletal muscle contraction (balance + posture)
-posterior to pons + medulla
what are the 2 functional systems of the brain?
-limbic system
-reticular formation
what is the limbic system?
-regulates emotions (laughing, crying, etc)
-nuclei in the cerebrum + diencephalon
-contains areas involved in memory (memories=emotional response)
what is the reticular formation?
-regulates alertness + attention
-sleepy when inhibited
-nuclei in brain stem
-cortex + thalamus + hypothalamus are involved
how does the reticular formation regulate alertness + attention?
-filters stimuli
-only sends new/unusual signals to other brain areas
what happens if the reticular formation is damaged?
-coma
what forms the reticular activating system (RAS)?
-cortex
-thalamus
-hypothalamus
what is the basic structure of the spinal cord?
-foramen magnum to L1/L2 (conus medullaris)
-nerves continue down through vertebral foramina as cauda equina (horses tail) (exit at intervertebral foramina)
-contains filum terminale
what is contained within the forebrain?
-cerebrum
what is the filum terminale?
-CT extension of the pia mater
-anchors the conus medullaris of the spinal cord to the coccyx
-where cerebrospinal fluid (CSF) samples are taken
what is contained within the cross sectional structure of the spinal cord?
-anterior median fissure
-posterior median sulcus
-central canal
-grey matter
-white matter
what does the anterior median fissure and posterior median sulcus separate?
-separates the spinal cord into right + left halves
what does the central canal of the spinal cord contain?
-cerebrospinal fluid (CSF)
what is the grey matter of the spinal cord?
-cell bodies + dendrites of motor neurons + interneurons
-H shaped
what is the crossbar of the gray H-shaped matter? what about the horns?
-cross bar = gray commissures
-dorsal horn = receives sensory information
-lateral horn = motor response
-ventral horn = motor response
what is the white matter of the spinal cord?
-myelinated axons
-contains ascending (sensory) tracts
-contains descending (motor) tracts
-forms 3 columns
what are the 3 columns of white matter in the spinal cord?
-dorsal column
-lateral column
-ventral column
what are the functions of the spinal cord?
-sensory + motor impulses
-produces reflexes
-fast + predictable + automatic responses to changes in environment
-ex: withdrawal reflex (arm away from a hot stove)
what cranial nerves are associated with the forebrain?
- I olfactory
- II optic
what cranial nerves are associated with the midbrain?
- III oculomotor
- IV trochlear
what cranial nerves are associated with the pons?
- V trigeminal
- VI abducens
- VII facial
- VIII vestibulocochlear
what cranial nerves are associated with the medulla oblongata?
- IX glossopharyngeal
- X vagus
- XI accessory
- XII hypoglossal
which 2 pairs of nerves are only sensory neurons?
- I olfactory
- II optic
which pair of cranial nerves is mainly sensory neurons?
- VIII vestibulocochlear
what are the remaining 9 pairs of cranial nerves composed of?
-mixed nerves
-both sensory + motor neurons
where are the cell bodies of the remaining cranial nerves motor neurons located?
-brainstem nuclei
where are the cell bodies of the remaining cranial nerves sensory neurons located?
-ganglia of the PNS
what is the motor and sensory function of the trigeminal nerve (V)
-motor = chewing
-sensory = conveys sensations (touch, pressure, pain, temp) from face to the CNS
how many pairs of spinal nerves are there? are they all one type of neuron or mixed?
-31pairs
-all mixed nerves
where is the location of all 31 spinal nerve pairs?
-8 cervical
-12 thoracic
-5 lumbar
-5 sacral
-1 coccygeal
where do the spinal nerves exit?
-exit at the intervertebral foramina
-except the 1st exits between the atlas + occipital bone
what are the 2 points of attachment to the spinal cord for each spinal nerve?
-dorsal root
-ventral root
what is in the dorsal root?
-sensory neurons with cell bodies in the dorsal root ganglion
what is in the ventral root?
-autonomic + somatic motor neurons with cell bodies in the ventral or lateral horn
what forms a spinal nerve?
-the joining of the dorsal + ventral roots
what do the spinal nerves immediately divide into?
-branches called rami
what are the 3 rami called?
-dorsal ramus
-ventral ramus
-rami communicantes
what does the dorsal ramus do?
-innervates (supplies with nerves) the skin + muscles of the back
what does the ventral ramus do?
-forms throacic nerves (T2-T12)
-also may further branch + join to form nerve plexuses (nerve network)
what are the 4 spinal nerve plexuses?
-cervical
-brachial
-lumbar
-sacral
what spinal nerves form the cervical spinal nerve plexus? what is the important nerve that arises?
- C1 - C5
-phrenic (innervates the diaphragm)
what spinal nerves form the brachial nerve plexus? what are the important nerves that arise?
- C5 - C8, T1
-axillary, radial, ulnar, median, musculocutaneous
what spinal nerves form the lumbar nerve plexus? what is the important nerve that arises?
- L1 - L4
-femoral
what spinal nerves form the sacral nerve plexus? what are the important nerves that arise?
- L4 - S4
-sciatic, divides into tibial + common fibular nerves
what is the rami communicantes?
-connect the ventral ramus to the sympathetic trunk
-contains autonomic nerve fibres (neurons)
what are the CT wrappings of a nerve?
-epineurium (around whole nerve)
-perineurium (around fascicles) (groups of nerves)
-endoneurium (around axon + myelin)
what is the path in the sensory (afferent) division?
-stimulus > receptor > CNS
what does the sensory (afferent) division of the PNS consist of?
-receptors
-first order neurons
what is the purpose of receptors?
-to detect changes in the environment
how are receptors classified?
-location
-type of stimulus received
-structure of the receptor (general senses only)
what are the different location receptors?
-exteroceptors
-interoceptors
-proprioceptors
what stimulus do exteroceptors detect? where are they? what senses?
-stimulus in the external environment
-receptors are at the body surface
-touch + special senses
what stimulus do interoceptors detect? where are they?
-stimulus in the internal environment
-in viscera (organs), blood vessels, etc
what are proprioceptors?
-monitor body position (stretch receptors, muscle spindles)
-balance + movement
-located in joints, skeletal muscles, etc
what are the receptors classified by their type of stimulus?
-mechanoreceptors
-thermoreceptors
-chemoreceptors
-photoreceptors
-nociceptors
what do mechanoreceptors detect?
-mechanical stimuli
-pressure, touch, hearing
what do thermoreceptors detect?
-temperature
what do chemoreceptors detect?
-chemical
what do photoreceptors detect?
-light
what do nociceptors detect?
-pain
what are the two structures of a receptor?
-free nerve endings
-encapsulated nerve endings
what are free nerve endings?
-terminal dendrites of unipolar sensory neurons
-ex: pain, root hair plexus
what are encapsulated nerve endings?
-terminal dendrites enclosed in CT
-ex: meissner’s + pacinian corpuscles
what are first order neurons?
-unipolar neuron attached or associated with a receptor (may be encapsulated instead of free)
-axon travels in cranial/spinal nerves to the CNS
where are the cell bodies of the first order neurons?
-sensory ganglia of cranial nerves
-dorsal root ganglia of spinal cord
where are the axon terminals of the first order neurons?
-brain
-dorsal horn of the spinal cord
what is the path in the motor (efferent) division of the PNS?
-CNS > effector
what are the 2 subdivisions of the motor (efferent) division of the PNS?
-somatic
-autonomic
what is the somatic division of the motor (efferent) division of the PNS?
-skeletal muscle = effector (voluntary)
-consists of lower motor neurons
what are lower motor neurons?
-single multipolar neuron
-cell bodies in the CNS and axons in the PNS
where are the cell bodies of neurons located in the somatic division of the motor (efferent) division of the PNS?
-ventral horn of the spinal cord
-motor nuclei of the brainstem (ex: facial motor nucleus for the cranial nerve VII)
what is the autonomic division of the motor (efferent) division of the PNS?
-smooth muscle, cardiac muscle, glands = effector (involuntary)
-2 consecutive multipolar neurons from the CNS to the effector
what are the 2 neurons of the autonomic division?
-preganglionic neuron
-postganglionic neuron
what is the preganglionic neuron?
-myelinated
-cell body in the brain stem or lateral horn of the spinal cord (in the CNS)
what is the postganglionic neuron?
-unmyelinated
-cell body in the autonomic ganglion (outside the CNS)
what are the 2 subdivisions of the autonomic division of the PNS (efferent)?
-sympathetic (SNS)
-parasympathetic (PSNS)
what is the sympathetic nervous system (SNS)?
-triggers fight or flight
-preganglionic neuron cell body is in the lateral horn (T1-L2)
-autonomic ganglia = trunk ganglia or collateral ganglia
-postganglionic neuron has a longer axon (bigger response)
-exit the CNS mainly as thoracic nerves
where is the trunk ganglia?
-either side of the vertebral column
what is the parasympathetic nervous system (PSNS)?
-rest + digest
-preganglionic neuron cell body is in the brain stem + S2-S4 (sacrum)
-autonomic ganglia = terminal ganglia
-postganglionic neuron has a short axon (smaller response)
-exit the CNS mainly via the vagus nerve (cranial nerve X)
where is the terminal ganglia?
-at or in the organ/effector wall
what are the two nervous system pathways?
-ascending (sensory)
-descending (motor)
what is an ascending nervous pathway?
-conducts impulses from general sense receptors into the brain
-3 consecutive neurons from the receptor to the cortex
what are the 3 consecutive neurons in the ascending pathways?
-first order neuron
-second order neuron
-third order neuron
where does the first order neuron of the ascending pathway lead? what type of neuron?
-receptor to the spinal cord (PNS)
-sensory neuron
what type of neuron is the second order neuron in the ascending pathway?
-interneuron, multipolar (CNS)
where is the cell body of the second order neuron in the ascending pathway?
-dorsal horn of the spinal cord or medulla (CNS)
-decussates (crosses over) in the medulla
what type of neuron is the third order neuron in the ascending pathway?
-interneuron, multipolar (CNS)
where is the cell body of the third order neuron in the ascending pathway? where does it impulse?
-in the thalamus
-impulses to the postcentral gyrus (sensory cortex) (CNS)
what forms the ascending spinal tracts?
-axons of the first and second order neurons
what are the 3 ascending spinal tracts?
-dorsal (posterior) column tract/pathway
-spinothalamic tract/pathway
-spinocerebellar tract/pathway
what is the dorsal (posterior) column tract/pathway?
-receptors could be free nerve endings or meissners
sensations can be precisely located (touch)
what is the spinothalamic tract/pathway
-temperature + pain receptors
-non-specific
-difficult to localize
what is the spinocerebellar tract/pathway?
-ascending tracts from the spinal cord to cerebellum
-receptors = proprioceptors (body position)
-no third order neuron, second order goes directly to the cerebellum
-no conscious perception because there is no crossing over (decussation)
what is a descending nervous pathway?
-conduct impulses from the brain to the effector
-2 neuron pathway
what are the 2 neurons in the descending pathway?
-upper motor neuron
-lower motor neuron
what is an upper motor neuron? where are their cell bodies located?
-multipolar interneurons
-cell bodies are in the cortex or brainstem nuclei
-in the CNS
what forms the descending spinal tracts?
-axons of the upper motor neurons
what are the 2 descending spinal tracts?
-corticospinal tracts
-indirect tracts
what is the corticospinal tract?
-cell bodies are in the cerebral cortex
-tracts mainly cross over (decussate) in the medulla
what is the indirect tract?
-cell bodies are in the brainstem nuclei
-receive impulses from the motor cortex, basal nuclei, and cerebellum
what is the relationship between the CNS and PNS?
-receptors detect stimuli
-afferent division of the PNS has sensory neurons that go into the CNS
-efferent division of the PNS has motor neurons that leave the CNS
-effectors execute a response (muscles + glands)
what is an example of how the CNS and PNS works together?
-hand touches something hot (stimulus) triggers a sensory receptor
-triggers the CNS and creates a response
-pull hand away (effector)
what are the 2 divisions of the motor/efferent division of the PNS?
-somatic (skeletal muscle)
-autonomic (smooth muscle, cardiac muscle, and glands)
what are the 2 divisions of the autonomic division of the motor/efferent division of the PNS
-sympathetic (SNS, fight or flight)
-parasympathetic (PSNS, rest and digest)
what is the pathway for production and reabsorption of CSF?
-produced by the choroid plexuses
-secreted into the lateral ventricles (1st + 2nd)
-moves into the 3rd ventricle via the interventricular foramina
-moves into the 4th ventricle via the cerebral aqueduct
-moves into the subarachnoid space of the brain and spinal cord via median (1) and lateral (2) apertures
-absorbed into the dural sinus (venous blood) via arachnoid villi
-moves to the internal jugular veins and to the heart
-then moves into arterial blood and goes back to the choroid plexuses
what is the posterior blood flow to the brain?
-vertebral arteries > basilar artery > posterior cerebral arteries (part of the circle)
what is the anterior blood flow to the brain?
-internal carotid arteries > middle cerebral arteries (not part of the circle)
-internal carotid arteries > anterior cerebral arteries (part of the circle) > anterior communicating artery (part of the circle)
-internal carotid arteries > posterior communicating artery (part of the circle)
how does blood return from the brain posteriorly?
-cerebral arteries > capillaries > cerebral veins > dural sinuses > superior vena cava
what does the anterior communicating artery join?
-the two anterior cerebral arteries
what are the 2 bulges/pyramids in the medulla?
-large motor tracts
-part of corticospinal tracts
how many cranial nerves are there?
-12 pairs
where is the collateral ganglia?
-close to large abdominal arteries
