How can we help?

You can also find more resources in our Help Center.

309 terms

A&P Nervous System

STUDY
PLAY
The white matter of the spinal cord contains
bundles of axons with common origins, destinations, and functions
In the spinal cord, white matter is separated into ascending and descending tracts organized as
columns
layer of connective tissue that surrounds individual axons within a peripheral nerve is termed
subarachnoid space
dorsal and ventral root of each spinal segment unite to form
spinal nerve
Each peripheral nerve provides
both motor AND sensory and motor OR sensory
Cerebrospinal fluid flows within the
subarachnoid space
stretch reflex
both is important in regulating muscle length and is activated when a skeletal muscle lengthens
The spinal cord continues to elongate until about age
4 years
If the dorsal root of a spinal nerve is severed
sensory input would be blocked
Blood vessels that supply the spinal cord run along the surface of the
pia mater
In meningitis
all of these
Spinal nerves are
both sensory and motor
The anterior horns of the spinal cord contain mainly
somatic motor nuclei.
The preganglionic fibers that connect a spinal nerve with an autonomic ganglion in the thoracic and lumbar region of the spinal cord form
white rami communicantes
The reflex movement of the head toward a loud noise is directed by the mesencephalon. Which nuclei accomplish this
inferior colliculi
Cerebrospinal fluid
is secreted by ependymal cells
Which of the following symptoms would you associate with damage to the spinal accessory nerve
weakness of the sternocleidomastoid muscle
region of the brain responsible for predicting the consequence of events or actions is
prefrontal cerebral cortex.
respiratory rhythmicity center is located in
the medulla oblongata.
Sensory information is processed and relayed to the cerebrum by the
thalamus
The highest levels of information processing occur in the
cerebrum
The dural sinuses are located in the
dural folds
Damage to the premotor cortex of the frontal lobe would interfere with the ability to
play the piano
Which of these is not one of the main divisions of the adult brain
prosencephalon
The cerebellum can be permanently damaged by stroke or temporarily affected by drugs or alcohol
ataxia
Damage to the corpora quadrigemina would interfere with
visual and auditory reflex movements of the head and neck
Which of the following is a function of the thalamus
process sensory information and relay it to the cerebrum
The cardiovascular reflexes are based in the
medulla oblongata
Sensory innervation of the lower teeth and gums is by the ________ nerve
mandibular branch of the trigeminal
The postural muscles of the body and making rapid adjustments to maintain balance and equilibrium are functions of the
cerebellum
CSF circulates, ________ between it and the interstitial fluid of the CNS is unrestricted between and across the ependyma
diffusion
Parkinson disease is the result of
inadequate production of dopamine by substantia nigra neurons
medulla oblongata regulates
both blood pressure and respiration
patient develops a tumor of a cranial nerve that leads to difficulty in speaking from a loss of tongue movement
hypoglossal
Each lateral ventricle communicates with the third ventricle through
interventricular foramen
The control of heart rate and blood pressure is based in the
medulla oblongata
Damage to the preoptic area of the hypothalamus leads to which problem
reduced ability to regulate body temperature
Hydrocephalus or "water on the brain" may
result from excessive production of cerebrospinal fluid or result from blockage of circulation of CSF
cranial nerve that has three major branches is the
trigeminal
Which of the following is a property of the blood-brain barrier
all of these
white matter of the cerebellum forms the
arbor vitae
IPSPs (inhibitory postsynaptic potentials)
are local hyperpolarizations
Cholinergic synapses release the neurotransmitter
acetylcholine
Integral membrane proteins that connect electrical synapses are called
connexons
the process of continuous action potential propagation
the action potential is triggered by graded depolarization of the initial segment,...
Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons
The axon would be unable to generate action potentials
Clusters of RER and free ribosomes in neurons are called
Nissl bodies
The ion that triggers the release of acetylcholine into the synaptic cleft is
calcium
Functions of astrocytes include all of the following, except
conducting action potentials
In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by
forming a cellular cord that directs axonal regrowth
How does blocking retrograde axoplasmic transport in an axon affect the activity of a neuron
The soma becomes unable to respond to changes in the distal end of the axon
The ________ nervous system controls the skeletal muscles
somatic
Extensive damage to oligodendrocytes in the CNS could result in
loss of sensation and motor control
The all-or-none principle states that
all stimuli great enough to bring the membrane to threshold will produce identical action potentials
Which of the following types of nerve fiber possesses the fastest speed of impulse propagation
type A
Glial cells that surround the neurons in ganglia are
satellite cells
Most CNS neurons lack centrioles. This observation explains
why CNS neurons cannot regenerate
The effect that a neurotransmitter has on the postsynaptic membrane depends on
all of these
The site of intercellular communication between neurons is the
synapse
Deteriorating changes in the distal segment of an axon as a result of a break between it and the soma is called ________ degeneration
Wallerian
The ________ nervous system is composed of the brain and spinal cord
central
Any stimulus that opens ________ ion channel will produce a graded potential
any of these
If the permeability of a resting axon to sodium ion increases,
both the membrane potential will depolarize and inward movement of sodium ion will increase
Opening of sodium channels in the axon membrane causes
both depolarization and increased positive charge inside the membrane
Adrenergic synapses release the neurotransmitter
norepinephrine
The rabies virus travels to the CNS via
retrograde axoplasmic transport
Neurotransmitter for release is stored in synaptic
vesicles
Each of the following is an example of a neuroeffector junction, except the junction between a neuron and a
nerve cell.
The first step in the process of photoreception is
absorption of a photon by a visual pigment
Olfactory information is first received by which part of the brain
cerebrum
The opening in the iris through which light passes is the
pupil
A loud noise causes
all of these
Which of the following is not one of the six primary taste sensations
peppery
The largest numbers of taste buds in adults are associated with the
circumvallate papillae
Before an olfactory receptor can detect an odorant, it has to
bind to receptors in olfactory cilia
The space between the cornea and the iris is the
anterior cavity
The middle ear communicates with the nasopharynx through the
auditory tube
When a rod is stimulated by light
all of these
In which of the following cases would the focal distance be greater
a flat lens
The vibrations received by the tympanic membrane are transferred to the oval window by the
auditory ossicles
When all three cone populations are stimulated equally, we perceive
white
Which of the following statements about the retina is TRUE
all of these are true.
Taste receptors are distributed in which of the following places
all of these
Which of the following descriptions best matches the term stapes
seals the oval window
The external ear ends at the
tympanic membrane
A pigment synthesized from vitamin A is
retinal
A sty
all of these
A ray of light entering the eye will encounter these structures in which order?
conjunctiva cornea aqueous humor .....
All of the following compose the epithelial projections found on the tongue, except
gustatory papillae
The gelatinous material that gives the eyeball its basic shape is the
vitreous humor
If your vision is 20/15, this means that you can
see objects at 20 feet that individuals with normal eyesight can see at 15 feet
Which of the following is a function of tears
all of these
An adult has approximately ________ taste buds
3000
Which of the following descriptions best matches the term otoliths
tiny weights necessary for the static sense of equilibrium
In the light-adapted state
photoreceptors are much less sensitive to stimulation
Taste buds are monitored by cranial nerves
VII, IX, X
The taste sensation that is triggered by the amino acid glutamate is known as
umami
Sound waves are converted into mechanical movements by the
tympanic membrane
A sudden rise of room brightness would cause
contraction of the sphincter pupillary muscles
Which of the following descriptions best matches the term ossicles
transmit movement of the tympanic membrane to the inner ear
The vibrations received by the tympanic membrane are transferred to the oval window by the
auditory ossicles
Gravity and linear acceleration are sensed in the
saccule and utricle
The shape of the lens is controlled by the
ciliary muscles
A normal, relaxed inhalation carries about ________ of the inhaled air to the olfactory organs
2 percent
Which of the following produces a lipid-rich secretion that prevents the upper and lower eyelids from sticking together at their edges
tarsal gland
Perception of gravity and linear acceleration depends on
the force exerted by otoliths on hair cells of the maculae
Visual pigments are derivatives of the compound
rhodopsin
The frequency of a perceived sound depends on
which part of the cochlear duct is stimulated
Why do things look blurry underwater without dive goggles or mask
Rather than air, light is moving from water into the cornea and is thus refracted too little for a sharp focus
The vitreous body
helps to stabilize the eye and give physical support to the retina
What structure changes the shape of the lens for far and near vision
ciliary body
Which of the following descriptions best matches the term aqueous humor
excessive production may lead to glaucoma
All of the following are true of the lacrimal glands, except that they
produce a strongly hypertonic fluid.
The quantity of neurotransmitter that is released by a hair cell
responds to almost any mechanical stimulation of the hair cell, is sensitive to which way stereocilia are bent with respect to the kinocilium, and determines if a sensory neuron will be excited
The cranial nerve that has three major branches is the
trigeminal
Difficulties in estimating temporal relationships between events may stem from damage to
the prefrontal cortex
The brain requires a substantial blood supply. The vessels that deliver blood to the brain are the
internal carotid arteries and vertebral arteries only
Autonomic centers that control blood pressure, heart rate, and digestion are located in the
medulla oblongata
The thin partition that separates the first and second ventricles is the
septum pellucidum
The cranial nerves that innervate the eye muscles are
III, IV, and VI.
The cerebellum and pons develop from the
metencephalon
The white matter of the cerebellum forms the
arbor vitae
Absorption at the arachnoid granulations returns CSF to the
venous circulation
The two cerebral hemispheres are separated by the
longitudinal fissure
Cerebrospinal fluid enters the subarachnoid space through the
lateral and median apertures
Increased production and release of acetylcholine by the neurons of the cerebral nuclei would result in
spastic, uncontrolled muscle contractions
Overseeing the postural muscles of the body and making rapid adjustments to maintain balance and equilibrium are functions of the
cerebellum
As CSF circulates, ________ between it and the interstitial fluid of the CNS is unrestricted between and across the ependyma
Diffusion
The optic tracts carry visual information from the retina to the
lateral geniculates
The medulla oblongata relays auditory information to the
inferior colliculi.
What structure is covered by many blood vessels and adheres tightly to the surface of the brain
pia mater
The medulla oblongata regulates
both blood pressure and respiration
Integrative centers concerned with the performance of complex processes are restricted to either the left or the right hemisphere. These complex processes include
all of these
The respiratory rhythmicity center is located in
the medulla oblongata
The primary motor cortex is the surface of the
precentral gyrus
Higher-order functions
all of these
Which of the following is a function of the hypothalamus
all of these
The auditory cortex is located in the
temporal lobe
Which antibiotic enters the CNS without difficulty because it easily crosses the blood-brain barrier
sulfadiazine
Divisions of the cerebral hemispheres that are named after the overlying skull bones are
lobes
Damage to the substantia nigra causes a decrease in the neurotransmitter dopamine. This causes a gradual, generalized increase in muscle tone, which is the main symptom of
Parkinson disease
Damage to the pyramidal cells of the cerebral cortex would directly affect
voluntary motor activity
A reflex that is used to assess the sensory function of the trigeminal nerve is the ________ reflex
corneal
Each lateral ventricle communicates with the third ventricle through a
interventricular foramen
The cerebellar hemispheres are separated by a band of cortex called the
vermis
Recognized neuronal circuit patterns include all of the following, except
multipolar
The outward projections from the central gray matter of the spinal cord are called
horns
The outermost connective-tissue covering of nerves is the
epineurium
Samples of CSF for diagnostic purposes are normally obtained by placing the tip of a needle in the
subarachnoid space.
Muscles of the neck and shoulder are innervated by spinal nerves from the ________ region
cervical
As the ________ nerve approaches the knee, it divides into two branches, the fibular nerve and the tibial nerve
sciatic
Compared to the vertebral column, the spinal cord is
shorter
The layer of connective tissue that surrounds individual axons within a peripheral nerve is termed the
endoneurium
Reflexes based on synapses formed during development are ________ reflexes.
innate
Enlargements of the spinal cord occur
in those spinal segments that control the limbs
The stretch reflex
both is important in regulating muscle length and is activated when a skeletal muscle lengthens
The layer of the meninges in direct contact with the spinal cord is the
pia mater
The tough, fibrous, outermost covering of the spinal cord is the
dura mater
The ventral root of a spinal nerve contains
axons of motor neurons.
In the condition ________, a virus infects dorsal root ganglia, causing a painful rash whose distribution corresponds to that of the affected sensory nerves as seen in their dermatomes
shingles
The layer of connective tissue that surrounds a fascicle within a peripheral nerve is the
perineurium
In which of the following would the delay between stimulus and response be greater
a polysynaptic reflex
If a person has a crush injury to the C3-C5 spinal segments, you would expect that he
might be unable to breathe on his own
Somatic motor neurons in the spinal cord control all of the following muscles, except those that
move the neck
The spinal cord consists of five regions and ________ segments.
31
The ventral rami form four major plexuses, including all of the following, except the ________ plexus
nuchal
After age ________ the vertebral column continues to elongate, but the spinal cord itself does not
4
If the dorsal root of a spinal nerve is severed
sensory input would be blocked
The dorsal root of a spinal nerve contains
axons of sensory neurons
A dorsal and ventral root of each spinal segment unite to form a
spinal nerve
The epidural space contains
connective tissue and blood vessels
A viral disease that destroys the cells of the anterior gray horn will
lead to muscle weakness or paralysis
If a person has a crush injury to the C3-C5 spinal segments, you would expect that he
might be unable to breathe on his own
Axons crossing from one side of the spinal cord to the other within the gray matter are found in the
gray commissures
The brachial plexus gives rise to all of the following nerves, except the
phrenic
The reflex that prevents a muscle from exerting too much tension is the ________ reflex
tendon
Neurons that have one axon and one dendrite, with the soma in between, are called
bipolar
Active neurons need ATP to support which of the following
all of these
Damage to ependymal cells would most likely affect the
formation of cerebrospinal fluid
Many medications introduced into the bloodstream cannot directly affect the neurons of the CNS because
the endothelium of CNS capillaries forms a blood-brain barrier
If the potassium permeability of a resting neuron increases above the resting permeability, what effect will this have on the transmembrane potential
The inside of the membrane will become more negative
If the axon terminal of a motor neuron suddenly became permeable to calcium ion
the motor end plate will be depolarized
Which of the following are properties of cerebrospinal fluid
all of these
Ions can move across the plasma membrane in which of the following ways
all of these
The smallest neuroglia of the CNS are the
microglia
In which of the following would the rate of impulse conduction be the greatest
a myelinated fiber of 10-µm diameter
Which of the following is the most important excitatory neurotransmitter in the brain
glutamate
The axon is connected to the soma at the
axon hillock
In a(n) ________ neuron, the dendrites and axon are continuous or fused
unipolar
After acetylcholinesterase acts, the synaptic knob
reabsorbs the choline
Small, wandering cells that engulf cell debris and pathogens in the CNS are called
microglia
Ion channels that are always open are known as
leak channels
Neurons that are rare, small, and lack features that distinguish dendrites from axons are called
anaxonic
In the process of continuous action potential propagation
the action potential is triggered by graded depolarization of the initial segment
After a stroke, what type of glial cell accumulates within the affected brain region
microglia
For which of the following functions do active neurons require a supply of ATP
all of these
Opioids relieve pain by blocking the release of
substance P
Graded potentials
may be either a depolarization or a hyperpolarization
If the chemically gated sodium channels in the postsynaptic membrane were completely blocked
synaptic transmission would fail
in the extracellular fluid surrounding a nerve cell will have which effect
...
Functions of astrocytes include all of the following, except
conducting action potentials
The efferent division of the peripheral nervous system innervates
all of these
Presynaptic facilitation by serotonin is caused by
calcium channels in the presynaptic membrane remaining open longer
Which of the following is not a function of the nervous system
direct long-term functions, such as growth
Sensory neurons of the PNS are
unipolar
In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by
forming a cellular cord that directs axonal regrowth
Which of the following is not a possible drug effect on synaptic function
change the type or receptor found in the postsynaptic membrane
The axoplasm of the axon contains which of the following
all of these
Neurons that have several dendrites and a single axon are called
mulitpolar
The region of the brain responsible for predicting the consequence of events or actions is the
prefrontal cerebral cortex
Droopy eyelids and double vision can result from injury to the ________ nerve
oculomotor
A patient develops a tumor of a cranial nerve that leads to difficulty in speaking from a loss of tongue movement. Which cranial nerve is affected
hypoglossal
A neural cortex is found on the surface of the
cerebral hemispheres and cerebellum only
Which of the following help to protect the brain
all of these
The tracts that connect the cerebellum to the brain stem are located in the
pons
The layer of the meninges that closely follows every gyrus and sulcus is the
pia mater
Somatic sensory axons enter the ventral root and usually ascend directly to the thalamus
Both parts of the statements are false
The descending spinal tract that crosses to the opposite side of the body within the cord is the ________ tract
anterior corticospinal
Which of the following kinds of information do fine-touch and light-pressure mechanoreceptors provide
all of these
The spinal tract that normally plays a minor role in the control of the distal muscles of the arms is the ________ tract.
rubrospinal
A highly sensitive tactile receptor composed of dendritic processes of a single myelinated fiber that makes contact with specialized cells of the stratum germinativum is a
tactile (Merkel) disc
Chemoreceptors are located in all of the following, except
in the skin
In order for a sensation to become a perception
it must received by the somatosensory cortex
A receptor potential may
be any of these
Which of the following is not a property of thermoreceptors
tonic response to temperature change
The spinal tract that relays information concerning pain and temperature to the CNS is the
lateral spinothalamic
Each of the following is an ascending tract in the spinal cord, except the
reticulospinal tract
Which of the following can contribute to receptor specificity
any of these
Which of the following is not one of the special senses
vibration
Mechanoreceptors might detect which of the following sensations
all of these
Which of the following is sometimes called "prickling pain"?
fast pain
A brain injury to a patient results in facial paralysis. Which descending tract is most likely affected
corticobulbar tract
Based on the motor homunculus, which of the following body regions has the largest motor units
back
Branches that may occur along an axon are called
collaterals
The term general senses refers to sensitivity to all of the following, except
taste
The general senses
involve receptors that are relatively simple in structure
Conscious and subconscious motor commands control skeletal muscles by traveling over the
any of these
If the primary motor cortex is destroyed, fine control of movement will be lost, but movement may not be lost completely because the medial and lateral pathways can still provide coarse motor control
Both parts of the statements are true
The cerebellum
has all these characteristics
We can localize sensations that originate in different areas of the body because
sensory neurons from specific body regions project to specific cortical regions
Our perception of our environment is imperfect for all of the following reasons, except that
receptors respond in an all-or-nothing manner
Destruction of or damage to a lower motor neuron in the somatic nervous system produces
flaccid paralysis of its muscle fibers (motor unit).
Sensations of burning or aching pain
cause a generalized activation of the reticular formation and the thalamus
Neurons from the nucleus gracilis
decussate before entering the medial lemniscus.
Complex motor activities such as riding a bicycle
require the coordinated activity of several regions of the brain
Which ascending tract carries the sensations for fine touch and vibration
posterior (dorsal) column
The spinal tract that unconsciously maintains balance and muscle tone is the ________ tract
...
Upper motor neurons are located in the
both precentral gyrus and brain stem
The cerebellum relies on information from
all of these
Gustatory receptors are sensitive to dissolved chemicals but insensitive to light. This is due to
receptor specificity
Your uncle was just diagnosed with a heart attack. One of his major symptoms is left arm pain. You are not surprised because you are familiar with the phenomenon of
referred pain
The medial and lateral motor pathways can modify, or direct, skeletal muscle contractions by ________ lower motor neurons
any of these
Which of the following is true about the relation between stimulus intensity and its neural representation
...
Stimulation of a neuron that terminates in the superior region of the left postcentral gyrus would produce
...
Sensory information that arrives at the CNS is routed according to the ________ of the stimulus
both modality and location
A tactile receptor composed of highly coiled dendrites that are surrounded by modified Schwann cells and a fibrous capsule is a
tactile (Meissner) corpuscle
Tactile receptors composed of capsules that surround a core of collagen fibers intertwined with dendrites are called
Ruffini corpuscles
The medial pathway that controls involuntary movements of head, neck, and arm position in response to sudden visual and auditory stimuli is the ________ tract
tectospinal
________ are receptors in the aorta that monitor the blood pressure
Baroreptors
Most sympathetic effector junctions release norepinephrine but a significant number release acetylcholine instead. Which of these is an example of an organ of the cholinergic type
a sweat gland
Stimulation of the beta receptors on heart muscle cells results in
the formation of cAMP, increased heart rate, and increased force of contraction
Ganglionic neurons innervate such things as
any of these
The suprarenal medullae secrete
both epinephrine and norepinephrine
Nicotinic receptors
open chemically gated sodium ion channels
The conscious state is maintained by the
reticular activating system
The brain waves produced by normal adults while resting with their eyes closed are ________ waves
alpha
Changes in the central nervous system that accompany aging include
all of these
Sweat glands contain ________ receptors
muscarinic cholinergic
What mental illness is often improved by drugs that block serotonin re-uptake
depression
During sympathetic activation, ________ occurs
all of these
Sympathetic nerves
are bundles of postganglionic fibers that innervate organs within the thoracic cavity
In general, parasympathetic preganglionic fibers are ________ and postganglionic fibers are ________
both myelinated; unmyelinated and long; short
Almost 75 percent of all parasympathetic outflow travels along the
vagus nerves
Alzheimer disease is characterized by all of the following, except that it
has a clear genetic basis
Drugs that stimulate alpha receptors, causing constriction of peripheral vessels, are
sympathomimetic
Postganglionic fibers that innervate targets in the body wall or thoracic cavity originate on neurons within
sympathetic chain ganglia
Which of the following statements about adrenergic receptors is true
all of these
A state of unconsciousness in which an individual can be aroused by normal stimuli is
sleep
Conversion of a short-term memory to a long-term memory is called
memory consolidation
Drugs that block nicotinic receptors would be
autonomic blocking agents
Hallucinogenic drugs, such as LSD, function by
stimulating serotonin receptors
The parasympathetic nervous system is especially active during which physiological state
digestion
Which of the following is essential for memory consolidation
hippocampus
An age-related decline in mental function characterized by difficulties with spatial orientation, memory, language, and personality is called
senile dementia
The stimulation of beta-adrenergic receptors can lead to
an increase in metabolic activity, an inhibition of airway smooth muscle, and the breakdown of triglycerides within adipocytes
A person is confronted by a dangerous dog. His heart begins to race and beat strongly, his pupils dilate, and his hairs stand up. These signs are the result of
sympathetic activation, increased levels of epinephrine in the blood, and increased activity of autonomic centers in the hypothalamus
Which of the following visceral reflexes is not coordinated by the medulla oblongata
pupillary reflex
Mary accidentally ate poison mushrooms that contain muscarine. What symptoms would you expect to observe
all of these
Which of these provides preganglionic parasympathetic innervation to structures in the neck and in the thoracic and abdominopelvic cavities
vagus nerves
In deep sleep
the EEG pattern is characterized as "slow wave."
A state of unconsciousness in which an individual cannot be aroused even by strong stimuli is
coma
Postganglionic sympathetic axons release the neurotransmitter ________ at their effector junctions
acetylcholine, nitric oxide, or norepinephrine
Long-term memories that are with you for a lifetime are called
tertiary memories
Which of the following would lead to increased heart rate
both increased sympathetic input and decreased parasympathetic input
Which of the following is not a parasympathetic ganglion
celiac ganglion
An inhaler used to treat airway constriction in asthma or allergy might contain a drug that
activates b2 adrenergic receptors or blocks muscarinic colienergic receptors
Mechanisms involved in memory formation and storage involve all of the following, except
anterograde amnesia
A doctor places drops in the eyes to dilate the pupils for an examination. The type of drug that is used is
a sympathomimetic drug, a muscarinic blocking drug, or an adrenergic activating drug
In general, sympathetic preganglionic fibers are ________ and postganglionic fibers are ________
both myelinated; unmyelinated and short; long
Drugs known as beta-blockers may be useful for treating
excessive heart rate
Parasympathetic functions include all of the following, except
dilation of the airways
The ________ division of the autonomic nervous system is said to function during "rest and digest."
parasympathetic
Parasympathetic stimulation
increases gastric motility
Preganglionic neurons of the sympathetic nervous system are located in the
lateral gray horns of segments T1 to L2 of the spinal cord.
Control of the diameter of the respiratory passages depends upon
both parasympathic and sympathic stimulatiom
Preganglionic fibers that innervate the collateral ganglia form the
splanchnic nerves
Sympathetic innervation of the urinary bladder is by way of the
inferior messenteric gangalion
Raising the potassium ion concentration in the extracellular fluid surrounding a nerve cell will have which effect
both depolarize it and decrease the magnitude of the potassium equilibrium potential
There are ________ pairs of cranial nerves
12