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University of Santo Tomas
College of Nursing
Assessment ofNeurologic
System
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Anatomy and Physiology
Nervous System
Central Nervous System Peripheral Nervous System(Brain and Spinal Cord) (Cranial and Spinal Nerves)
Somatic Autonomic(Voluntary) (Involuntary)
Sympathetic Nervous System Parasympathetic Nervous System
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Neurons
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Neuroglia
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Neurotransmitters
Excitatory; pleasurablesensation; inhibits pain
transmission
Nerve terminals in the spine,brain stem, thalamus,
pituitary gland
Enkephalin,
Endorphin
Inhibitory; muscle andnerve transmission
Spinal cord, cerebellum,basal ganglia
Gamma-aminobutyricacid (GABA)
Usually excitatoryBrain stem, hypothalamusNorepinephrine
Usually inhibitory;affects behavior and
fine motor
Substantia nigra and basalganglia
Dopamine
Inhibitory; helps controlmood and sleep
Brain stem, hypothalamus,dorsal horn of spinal cord
Serotonin
Usually excitatoryMajor areas of the brain;autonomic nervous system
Acetylcholine
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CENTRAL NERVOUS SYSTEM
Brain
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Brain
It is approx. 2% of the total body weight
It weighs approx. 1400 g in an averageyoung adult
In weighs an average of 1200 g in theelderly
It is divided into three major areas:cerebrum, brain stem and the cerebellum
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Cerebrum
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Cerebrum
It consists of two hemispheres that areincompletely separated by the greatlongitudinal fissure
It is separated into right and left hemispheresbysulcus
It is joined at the lower portion by corpuscallosum
It has wrinkled appearance due to presence of
folded layers or convolutions calledgyri
It has an external of outer portion made up ofgraymatterapprox. 2 to 5 mm in depth and ismade up of billions of neurons and cell bodies
It has an innermost layer made up of white
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Four Lobes of the Cerebrum
Frontal Lobe
Largest lobe
Controls concentration, abstract thought,
information storage or memory, and motorfunction
Contains Brocas area, a speech associationarea that participates in word formation
Responsible for large part of individualsaffect, judgment, personality and inhibitions
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Parietal Lobe
Predominantly a sensory lobe
Contains primary sensory cortex, which
analyzes sensory information and relaysthe interpretation of this information to thethalamus and other cortical areas
Controls awareness of the body in space,
orientation in space and spatial relations
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Temporal Lobe
Contains auditory receptive areas
Contains a vital area called interpretative
area, which provides integration ofsomatization, visual and auditory areas
Occipital Lobe
Contains visual areas, which playimportant role in visual interpretation
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Other Areas of Cerebrum
Corpus Callosum
Thick collection of nerve fibers thatconnects the two hemispheres of the brain
and is responsible for the transmission ofinformation from one side of the brain tothe other
Information transferred is sensory,
memoryand learned discrimination
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Basal Ganglia
Masses of nuclie located deep in thecerebral hemispheres
Responsible for motor control of fine bodymovements
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Thalamus
Lies on either side of the third ventricle
Acts primarily as a relay station for all
sensation except smell
All memory, sensation and pain impulsespass through this section
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Hypothalamus
Located anterior and inferior to the thalamus
It includes the optic chiasm and mamillary
bodies Plays a role in the regulation of pituitary
secretion of hormones that influencemetabolism, reproduction, stress response and
urine production Called as hunger and satiety centers
Regulates sleep-wake cycle, blood pressure,aggressive and sexual behaviors, and
emotional responses
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Pituitary Gland
Located at the sella turcica at the base ofthe brain
Divided into anterior and posterior sectionswhich secrete hormones necessary inmaintaining life
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Brain Stem
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Brain Stem
Contains the midbrain, pons and medullaoblongata
The midbrain contains sensory and motor
pathways and serves as the center for auditoryand visual reflexes
The pons contains motor and sensorypathways, and controls the heart, respiration
and blood pressure The medulla oblongata transmits both
sensory and motor fibers, and is the bodysrespiratory center
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Cerebellum
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Cerebellum
Separated from the cerebral hemispheresby a fold of dura matter, the tentoriumcerebelli
Has both excitatory and inhibitory actionsand is largely responsible for coordinationof movement
Controls fine movement, balance, position
sense and integration of sensory input
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Structures Protecting the Brain
Meninges
Fibrous connective tissues that cover thebrain and spinal cord
Provides protection, support andnourishment to the brain and spinal cord
Composed of dura mater, arachnoid and piamater
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Dura mater
Outermost layer
Tough, thick, inelastic, fibrous and gray in
color
Has four extensions: falx cerebri,tentorium, falx cerebelli anddiaphragma sellae
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Arachnoid
Middle membrane
Extremely thin, delicate membrane which
resembles a spider web
Appears white because of absence of bloodsupply
Contains the choroid plexus, which
produces the cerebrospinal fluid (CSF)
Contains arachnoid villi, which absorb CSF
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Pia mater
Innermost membrane
Thin, transparent layer that hugs the brain
closely and extends into every fold of thebrains surface
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Cerebrospinal Fluid (CSF)
Clear and colorless fluid with a specific gravity of1.007
Cushions and nourishes the brain
Produced in the ventricles and is circulated aroundthe brain and the spinal cord by the ventricularsystem
The organic and inorganic contents of CSF aresimilar to those of plasma but differs inconcentration
Analyzed for presence of protein, glucose, chlorideand immunoglobulins
Normally contains minimal number of WBCs andno RBCs
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Cerebral Circulation
The brain requires 20% of the oxygen ofthe body
The brain requires 65-70% of the glucosein the body
The brain requires 1/3 of the cardiac output
The brain does not store nutrients and hasa high metabolic demand that requires highblood flow
The brain lacks additional collateral bloodflow, which may result in irreversibledamage when blood flow is occluded
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Arterial Supply
The arterial blood supply to the brain isprovided by two internal carotid arteriesand two vertebral arteries
At the base of the brain, a ring is formedbetween the vertebral and internal carotidarterial chains called circle of Willis
The arterial anastomosis along the circle of
Willis is a frequent site of aneurysms
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Clipping of Aneurysm
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Craniotomy
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Venous Drainage
The veins of the brain reach the brainssurface and join larger veins which emptyinto the dural sinuses
Dural sinuses are vascular channels lyingwithin the tough dura mater
The network of the sinuses carries venousoutflow for the brain and empties into theinternal jugular veins, which return the
blood into the heart Cerebral veins and sinuses are unique
because they dont have valves
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Blood-Brain Barrier
Formed by the endothelial cells of the braincapillaries, which form continuous tightjunctions, creating a barrier to macro
molecules and many compounds All substances entering the CSF must filter
through the capillary membranes of thechoroid plexus
Often altered by trauma, cerebral edemaand cerebral hypoxemia
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Spinal Cord
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Spinal Cord
Serves as a connection between the brain andthe periphery
Approx. 45 cm (18 in) long and about thethickness of a finger
Extends from the foramen magnum at the baseof the skull to the lower border of the firstlumbar vertebra, where it tapers to a fibrousband conus medullaris
Below the second lumbar space are nerve rootsthat extend beyond the conus, which are calledcauda equina
Contains gray matter, located at the center,and white matter on its sides
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Sensory and Motor Pathways:The Spinal Tract
Fiber bundles with a common function arecalled tracts
There are six (6) ascending tractsconducting sensation such as perception oftouch, pressure, vibration, position andpassive motion from the same side of thebody
Ex. Spinocerebellar tracts - conduct
sensory impulses from muscle spindles,providing necessary input for coordinatedmuscle contraction
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There are eight (8) ascending tracts, sevenof which are engaged in motor function
Examples:
1. Corticospinal tracts (2) voluntary muscleactivity
2. Vestibulospinal tracts (3) autonomicfunctions such as sweating, pupil dilation andcirculation
3. Corticobulbar tract voluntary head andfacial muscle movement
4. Rubrospinal and reticulospinal tracts -involuntary muscle movement
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Vertebral Column
Surrounds and protects the spinal cord andconsists of 7 cervical, 12 thoracic, 5lumbar and 5 sacral
Nerve roots exit from the vertebral columnthrough the intervertebral foramina
Separated by disks, except for the first andsecond cervical, sacral and coccygealvertebrae
Each vertebra has a ventral solid body anda dorsal segment or arch, which is posteriorto the body
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PERIPHERAL NERVOUS SYSTEM
Cranial Nerves
There are 12 pairs of cranial nerves thatemerge from the lower surface of the brain
and pass through the foramina in the skull Three (3) are entirely sensory ( CN I, II,
VIII), five (5) are motor (CN III, IV, VI)and four (4) are mixed (CN V, VII, IX, X)
They are numbered in the order in whichthey arise from the brain
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Cranial Nerves
Trigeminal neuralgia
(Tic douloureux)
Controls muscles ofmastication;
sensations for theentire face
V. Trigeminal
NystagmusEye movement;controls superior
oblique
IV. Trochlear
Anisucuria; pinpointpupils; fixed, dilated
pupils
Pupil constriction;
elevation of upper lid
III. Oculomotor
Papilledema; blurredvision; scotoma;
blindness
VisionII. Optic
Anosmia
(absence of smell)
SmellI. Olfactory
Abnormal FindingsFunctionsCranial Nerves
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Tinnitus; vertigoCochlear branchpermits hearing;
vestibular branchhelps maintain
equilibrium
VIII. Acoustic/
Vestibulocochlear
Bells palsy; ageusia(loss of sense of taste)
on the anterior 2/3 ofthe tongue
Controls muscles forfacial expression;
anterior 2/3 of thetongue
VII. Facial
Diplopia; ptosis of theeyelid
Eye movements;controls the lateral
rectus muscle
VI. Abducens
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Protrusion of thetongue; deviation of
the tongue to one sideof the mouth
Movement of the tongueXII. Hypoglossal
Inability to rotate thehead and move the
shoulders
Controlssternocleidomastoid and
trapezius muscles
XI. Spinal Accessory
Loss of gag reflex;drooling of saliva;
dysphagia; dysarthria;bradycardia; increased
HCl secretion
Controls muscles of thethroat; PNS stimulation
of thoracic andabdominal organs
X. Vagus
Loss of gag reflex;drooling of saliva;
dysphagia; dysphonia;posterior third ageusia
Controls muscles of thethroat; taste of posterior
1/3 of the tongue
IX. Glossopharyngeal
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Spinal Nerves
Composed of 31 pairs of spinal nerves: 8cervical; 12 thoracic; 5 lumbar; 5 sacral;and 1 coccygeal
The dorsal roots are sensory and transmit
impulses from specific areas of the body, knownas dermatomes, to the dorsal ganglia
The sensory fibers maybe somatic, carryinginformation about pain, temperature, touch, and
position sense (proprioception) from thetendons, joints and body surfaces
Fibers can also be visceral, carrying informationfrom the visceral organs
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The ventral roots are motorand transmitimpulses from the spinal cord to the body
These fibers can either be somatic or
visceral The visceral fibers include autonomic
fibers that control the cardiac muscles andglandular secretions
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AUTONOMIC NERVOUS SYSTEM:
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Sympathetic Nervous System vs.Parasympathetic Nervous System
Dilated
Increased
Constricted
Decreased
Respiratory System:
Bronchioles
Rate of breathing
Dilated
Dilated
Constricted
Increased
Constricted
*
*
Decreased
Blood Vessels
In the heart muscle
In skeletal muscle
In abdominal viscera and skin
Blood pressure
IncreasedDecreased
Circulatory System:
Rate and force of heart beat
DilatedConstrictedPupil of the Eye
SNSPNSStructure or Activity
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Relaxed
Contracted
Contracted
Relaxed
Genitourinary System:
Urinary bladder
Muscular walls
Sphincters
Decreased
Contracted
Thick, viscid
*
Increased
Increased
Relaxed
Thin, watery
Increased
*
Digestive System:Peristalsis
Muscular sphincters
Secretion of salivary gland
Secretions of stomach,
intestine and pancreas
Conversion of liver
glycogen to glucose
SNSPNSStructure or Activity
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Secretion ofcatecholamines
*Adrenal Medullae
Increased
Contracted
*
*
Integumentary System:
Secretion of sweat
Pilomotor muscles
SNSPNSStructure or Activity