Assessment of Neurologic System

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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
http://en.wikipedia.org/wiki/File:Complete_neuron_cell_diagram_en.svg


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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

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Digestive System:Peristalsis

Muscular sphincters

Secretion of salivary gland

Secretions of stomach,

intestine and pancreas

Conversion of liver

glycogen to glucose



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Secretion ofcatecholamines

*Adrenal Medullae

Increased

Contracted

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Integumentary System:

Secretion of sweat

Pilomotor muscles


Assessment of Neurologic System

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