Ch. 11 Nervous System Flashcards
(138 cards)
1
Q
chiasm-
A
Cross
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flacc-
A
flabby
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Q
funi-
A
small cord or fiber
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gangli-
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Swelling
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mening-
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membrane
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plex-
A
interweaving
7
Q
The central nervous system (CNS) consists of
A
brain and the spinal cord.
8
Q
The brain is the largest and most complex part of the nervous system. It oversees many aspects of physiology,
A
sensation and perception, movement, and thinking.
9
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The brain connects to the spinal cord
A
through the brainstem
10
Q
Bones, membranes, and fluid surround the organs
A
of the CNS.
11
Q
meninges
A
Beneath these bony coverings, membranes called _____, located between the bone and the soft tissues of the nervous system, protect the brain and spinal cord
12
Q
The meninges are three connective tissue membranes:
A
dura mater, arachnoid mater, and pia mater
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Dura Matter
A
outermost layer of the meninges surrounding the brain and spinal cord
14
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Falx cerebelli
A
Separates the right and left cerebellar hemispheres
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Falx cerebri
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Extends downward into the longitudinal fissure, and separates the right and left cerebral hemispheres
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Tentorium cerebelli
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Separates the occipital lobes of the cerebrum from the cerebellum
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The arachnoid mater
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“spider like ,is a thin, web-like membrane that does not have blood vessels and is located between the dura and pia maters.
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A subarachnoid
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space between the arachnoid and pia maters contains the clear, watery cerebrospinal fluid
19
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The subarachnoid space of
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the meninges completely surrounds the brain and spinal cord, so these organs in effect float in the CSF.
20
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CSF in Meninges
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The fluid protects the brain and spinal cord by absorbing forces that might otherwise jar and damage their delicate tissues.
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The pia mater
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“gentle mother is thin and contains many nerves, as well as blood vessels that nourish the underlying cells of the brain and spinal cord.
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ventricles
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CSF is formed in four interconnected cavities called that lie in the cerebral hemispheres and brainstem and reference plates 13 and 14
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Structures called choroid plexuses
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Choroid plexuses in ventricle walls secrete cerebrospinal fluid. Most of the fluid circulates through the ventricles and enters the subarachnoid space, and is reabsorbed into the blood.
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Q
CSF in the whole system is what
A
is a clear, somewhat viscous liquid that differs in composition from the fluid that leaves the capillaries in other parts of the body.
helps maintain a stable ionic concentration in the CNS and provides a pathway to the blood for waste.
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The brain
sensory functions responsible for sensations perceptions. issues motor commands to skeletal muscle, mental functions memory reasoning , coordinates movements regulate visceral activities, personality
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A lumbar puncture (spinal tap) measures
CSF pressure.
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hydrocephalus,
In a fetus or infant whose cranial sutures have not yet united, increasing ICP may enlarge the cranium, or “water on the brain”
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BrainStem
Together, the midbrain, pons, and medulla oblongata comprise ____ which attaches the brain to the spinal cord.
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Brain forms 3 vesicles cavities
Forebrain Prosencephalon
Midbrain Mesencephalon
Hindbrain Rhombencephalon
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Forebrain / prosencephalon divides
into the telencephalon and diencephalon
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Midbrain mesencephalon
presist
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Hindbrain rhombencephalon
divides into metencephalon and myelencephalon
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Major portions of the brain
Cerebrum , Diencephalon, Cerebellum, Brainstem
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cerebral hemispheres
in the cerebrum
2 halves separated by falx cerebri
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Corpus callosum
in the cerebrum , connects cerebral hemispheres
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Gyri
in the cerebrum ridges or convolutions
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Sulci
In the cerebrum shallow grooves in surface example central sulcus
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Fissures
in cerebrum deep grooves in surface
longitudinal separates the cerebral hemispheres
Transverse separates cerebrum from cerebellum
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5 lobes of the cerebral hemispheres
frontal lobe
parietal lobe
temporal lobe
occipital lobe
Insula Island of reil deep within lateral sulcus.
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Cerebral Cortex
Thin layer of gray matter which makes up outermost layer of all outer lobes of the cerebrum
Contains almost 75% of neuron cell bodies in nervous system
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White matter of cerebrum
Lies under cerebral cortex
makes up most of cerebrum
contains bundles of myelinated axons that connect neuron cell bodies in cerebral cortex to other portions of nervous system.
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Functions of the Cerebral Cortex
interpreting impulses from sense organs, initiating voluntary muscular movements, storing information as memory, and retrieving this information in reasoning. intelligence and personality.
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cutaneous sensory area
cortex
parietal lobe
interprets sensations on skin
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Sensory speech are wernickes area
Cortex
Temporal parietal lobe usually left hemisphere
understanding and formulating language
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Visual area
Cortex
occipital lobe
interprets vision
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Auditory area
cortex
Temporal lobe
Interprets hearing
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Sensory area for taste
Cortex
Near base of the central sulcus
includes part of insula
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sensory area for smell
cortex
arises from centers deep within temporal lobes
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Association areas
analyze and interpret sensory experiences and help provide memory, reasoning, verbalizing, judgment, and emotions
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Frontal lobe association areas
Concentrating, planning, complex problem solving
* Emotional behavior, judging consequences of behavior
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Parietal lobe association areas:
* Understanding speech
* Choosing words to express thoughts and feelings
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Temporal lobe association areas:
* Interpret complex sensory experiences (understanding speech,
reading)
* Store memories of visual scenes, music, and complex patterns
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Occipital lobe association areas
Occipital lobe association areas:
* Analyze and combine visual images with other sensory experiences
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Insula does
* Translating sensory information into proper emotional responses
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Wernicke’s area is usually in the
left hemisphere, in the temporal lobe adjacent to the parietal lobe, near the posterior end of the lateral sulcus (fig. 11.8). This area is important for understanding and formulating written and spoken language.
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Primary motor areas (motor cortex):
Frontal lobes
* Control voluntary muscles
* Most nerve fibers cross over in brainstem
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Broca’s area:
* Anterior to primary motor cortex
* Usually in left hemisphere
* Controls muscles needed for speech
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Frontal eye field
* Above Broca’s area
* Controls voluntary movements of eyes and eyelids
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Dominant hemisphere controls:
Language skills of speech, writing, reading
* Verbal, analytical, and computational skills
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Nondominant hemisphere controls:
Nonverbal tasks
* Motor tasks involving orientation in space
* Understanding and interpreting musical and visual
patterns
* Provides emotional and intuitive thought processes
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corpus callosum nerve fibers
the large band of neural fibers connecting the two brain hemispheres and carrying messages between them
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short-term memory
performing a specific task, such as remembering a term that you want to look up long enough to type it into a search window.
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Long-term memory
can hold much more information than short-term memory and lasts a lifetime.
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long-term potentiation,
an increase in a synapse's firing potential after brief, rapid stimulation. Believed to be a neural basis for learning and memory.
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memory consolidation.
the neural storage of a long-term memory
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The basal nuclei, also called the basal ganglia,
are masses of gray matter deep within the cerebral hemispheres.
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Parkinson's Disease
degeneration of neurons in the basal ganglia, occurring in later life and leading to tremors, weakness of muscles, and slowness of movement
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Diencephalon
Composed of gray matter
* Portions of the diencephalon:
* Thalamus
* Hypothalamus
* Optic tracts
* Optic chiasma
* Infundibulum
* Posterior pituitary
* Mammillary bodies
* Pineal gland
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Thalamus:
* Gateway for sensory impulses ascending to cerebral cortex
* Receives all sensory impulses (except for sense of smell)
* Channels impulses to appropriate part of cerebral cortex for interpretation
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Hypothalamus:
* Maintains homeostasis by regulating visceral activities, such as heart rate,
blood pressure, body temperature, water and electrolyte balance, hunger,
body weight, movement and glandular secretion in digestive tract, sleep and
wakefulness, pituitary gland function
* Links nervous and endocrine systems
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Limbic system
* Consists of several structures in various parts of brain, including diencephalon
* Controls emotional responses, feelings, behavior oriented toward survival
* Reacts to potentially life-threatening upsets (physical or psychological)
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Brain stem consist of
* Midbrain
* Pons
* Medulla oblongata
* Contains nerve fiber tracts and gray matter masses
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Mid brain
Short section of brainstem
* Lies between diencephalon and pons
* Contains bundles of fibers that join lower parts of
brainstem and spinal cord with higher part of brain
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Cerebral aqueduct:
Mid Brain Connects 3rd to 4th ventricle
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Cerebral peduncles:
Mid Brain Main motor pathways that connect
cerebrum to lower portions of nervous system
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Corpora quadrigemina:
Mid Brain Centers for visual and auditory
reflexes
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Red nucleus:
Mid Brain Role in postural reflexes
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PONS Location
Rounded bulge on underside of brainstem
* Between midbrain and medulla oblongata
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PONS do what
* Relays nerve impulses between medulla oblongata and
cerebrum
* Relays impulses from cerebrum to cerebellum
* Helps regulate rhythm of breathing
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Medulla oblongata: conducts
* Enlarged continuation of spinal cord
* Conducts ascending and descending impulses between
brain and spinal cord
* Contains cardiac, vasomotor, and respiratory control
centers
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Medulla oblongata controls
Contains various nonvital reflex control centers (coughing,
sneezing, swallowing, and vomiting)
* Injuries are often fatal
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Cerebral peduncles
contain fibers that carry motor output from cerebrum to other regions of CNS
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reticular formation reticular activating system
nerve fibers associated with tiny islands of gray matter.
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reticular formation reticular activating system
Filters incoming sensory information, passing some to
cerebral cortex, and discarding unimportant information
* Arouses cerebral cortex into state of wakefulness
* Decreased activity causes sleep
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Sleep is
Sleep is a normal, recurring, and reversible state of unconsciousness characterized in part by limited sensory input and inhibited skeletal muscle activity.
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Non-rapid Eye Movement (Non-REM) Sleep:
Slow wave sleep
* Person is tired
* Decreasing activity of reticular formation
* Restful and dreamless
* Reduced blood pressure and respiratory rate
* 3 stages, ranging from light to heavy
* Alternates with REM sleep
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Rapid Eye Movement (REM) Sleep:
Called paradoxical sleep, because some areas of brain are active
* Heart and respiratory rates irregular
* Dreaming occurs
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cerebellar peduncles
The cerebellum communicates with other parts of the CNS by means of three pairs of nerve tracts called
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Spinal cord are
Slender column of nervous tissue continuous with brain
and brainstem
* Extends downward through vertebral canal
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Spinal Cord structure
Begins at the foramen magnum and terminates at the first
and second lumbar vertebrae (L1 to L2) space
* Consists of 31 segments; each gives rise to a pair of
spinal nerves
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Spinal Nerves
* Spinal nerves are grouped according to the level of the
vertebra with which they are associated
* Within each group, the pairs of nerves are numbered in
sequence from superior to inferior
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central canal,
contains CSF central canal is prominent during embryonic development, but it becomes almost microscopic in adulthood.
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The gray matter divides the white matter of the spinal cord into three regions on each side—the anterior, lateral, and posterior funiculi.
Each funiculus consists of longitudinal bundles of myelinated nerve fibers called tracts that compose the major pathways.
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The spinal cord has two main functions.
It is a center for spinal reflexes, and it is a conduit for impulses to and from the brain.
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Monosynaptic (stretch) reflex:
Contains 2 neurons, sensory and motor
* Has only 1 synapse in spinal cord
* Example: Patellar or knee-jerk reflex
* Helps maintain an upright posture
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Withdrawal Reflex does
Occurs when person touches or steps on something painful (stove,
tack)
* Prevents or limits tissue damage, by removing limb from painful
stimulus
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Polysynaptic
Withdrawal reflex contains sensory neuron, interneuron, motor neuron
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Reciprocal innervation:
Withdrawal Reflex flexors contract, extensors are inhibited
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reflex
Such a nerve pathway is called a
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Crossed Extensor Reflex:
During withdrawal reflex, flexors on affected (ipsilateral)
side contract, and extensors are inhibited
* At same time, extensors on opposite (contralateral) side
contract, flexors are inhibited
* Also shifts body weight, so person remains upright
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segmental innervation.
distribution of all motor and sensory nerve fibers from one spinal cord segment
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ascending tracts
carry sensory information to the brain
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descending tracts
carry nerve impulses away from the brain
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Fasciculus gracilis and fasciculus cuneatus
Conduct sensory impulses associated with the senses of touch, pressure, and body movement from skin, muscles, tendons, and joints to the brain
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spinothalamic tracts
Conduct sensory impulses associated with the senses of pain, temperature, touch, and pressure from various body regions to the brain
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spinocerebellar tracts
Conduct sensory impulses required for the coordination of muscle movements from muscles of the lower limbs and trunk to the cerebellum
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corticospinal tracts
Conduct motor impulses associated with voluntary movements from the brain to skeletal muscles
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reticulospinal tracts
Conduct motor impulses associated with the maintenance of muscle tone and the activity of sweat glands from the brain
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rubrospinal tracts
Conduct motor impulses associated with muscular coordination from the brain
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Peripheral Nervous System (PNS)
Cranial nerves arising from the brain
* Spinal nerves arising from the spinal cord
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Somatic nervous system
cranial and spinal nerves that connect
CNS to the skin and skeletal muscles (conscious activities)
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Autonomic nervous system:
cranial and spinal nerves that
connect CNS to viscera (subconscious activities)
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Nerve Fibers
are axons
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Nerves are
of axons
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Endoneurium:
Loos connective tissue that surrounds
individual axons
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Perineurium:
Loose connective tissue that surrounds
fascicles
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Epineurium:
Dense connective tissue that surrounds a
group of fascicles
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Sensory Nerves
* Conduct impulses into brain or spinal cord
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Motor nerves:
* Conduct impulses to muscles or glands
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Mixed nerves:
* Contain both sensory and motor nerve fibers
* Most nerves are mixed nerves
* All spinal nerves are mixed nerves (except the first pair)
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Cranial Nerves First Pair
has fibers that start in the nasal cavity
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Cranial Nerves Second pair originates
in eyes, fibers synapse in thalamus
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Cranial Nerves:
* 12 pairs on underside of brain
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Spinal Nerves 1
All are mixed nerves, except first pair (which is entirely motor)
Originate from spinal cord
31 pairs of spinal nerves:
* 8 cervical nerves, (C1 to C8)
* 12 thoracic nerves (T1 to T12)
* 5 lumbar nerves (L1 to L5)
* 5 sacral nerves (S1 to S5)
* 1 coccygeal nerve (Co)
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Cauda equina:
Formed by descending roots of lumbar, sacral,
and coccygeal nerves
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Dermatome:
An area of skin innervated by the sensory nerve
fibers of a particular spinal nerve (in all spinal nerves below C1)
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I Olfactory Sensory
Sensory
fibers conduct impulses associated with the sense of smell.
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II Optic Sensory
Sensory fibers conduct impulses associated with the sense of vision
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III Oculomotor Primarily
motor Motor fibers conduct impulses to muscles that raise the eyelids, move the eyes, adjust the amount of light entering the eyes, and focus the lenses.
Some sensory fibers conduct impulses associated with proprioceptors.
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IV Trochlear Primarily motor
Motor fibers conduct impulses to muscles that move the eyes.
Some sensory fibers conduct impulses associated with proprioceptors
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Trigeminal
Ophthalmic division
Maxillary division
Mandibular division Mixed
Sensory fibers conduct impulses from the surface of the eyes, tear glands, scalp, forehead, and upper eyelids.
Sensory fibers conduct impulses from the upper teeth, upper gum, upper lip, lining of the palate, and skin of the face.
Sensory fibers conduct impulses from the scalp, skin of the jaw, lower teeth, lower gum, and lower lip.
Motor fibers conduct impulses to muscles of mastication and to muscles in the floor of the mouth.
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VI Abducens
Primarily motor Motor fibers conduct impulses to muscles that move the eyes.
Some sensory fibers conduct impulses associated with proprioceptors.
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VII Facial
Mixed Sensory fibers conduct impulses associated with taste receptors of the anterior tongue. Also general sensory input from the nasal cavity, external ear, and the palate.
Motor fibers conduct impulses to muscles of facial expression, tear glands, and salivary glands.
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VIII Vestibulocochlear
Vestibular branch
Cochlear branch
Sensory Sensory fibers conduct impulses associated with the sense of equilibrium.
Sensory fibers conduct impulses associated with the sense of hearing.
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IX Glossopharyngeal Mixed
Sensory fibers conduct impulses from the pharynx, tonsils, posterior tongue, and carotid arteries.
Motor fibers conduct impulses to salivary glands and to muscles of the pharynx used in swallowing.
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X Vagus
Mixed Sensory fibers conduct impulses from the pharynx, larynx, esophagus, and viscera of the thorax and abdomen.
Somatic motor fibers conduct impulses to muscles associated with speech and swallowing; autonomic motor fibers conduct impulses to the viscera of the thorax and abdomen.
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XI Accessory
Cranial branch
Spinal branch Primarily motor Motor fibers conduct impulses to muscles of the soft palate, pharynx, and larynx.
Motor fibers conduct impulses to muscles of the neck and back; some proprioceptor input.
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XII Hypoglossal Primarily
motor Motor fibers conduct impulses to muscles that move the tongue; some proprioceptor input
