Wk 3 Nervous System 202

8/3/2019 Wk 3 Nervous System 202

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NERVOUS SYSTEM

Introduction

The NS can be thought of as having three major subdivisions:

1)The central nervous system (CNS)Brain

Spinal cord

2)The peripheral nervous system (PNS)Those nerves which pass from the CNS to the periphery of the body (Cranial nerves &Spinal

nerves)3)The autonomic nervous system (ANS) OR involuntary nervous system

Outside of the CNS and part of the PNSBody functions that are not under conscious control are regulated by the ANS.


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NEUROLOGICAL DISORDERS

Neurological conditions are disorders thatinvolve some portion of the nervoussystem. These conditions may result from

infections, deranged physiology, ortrauma. In all cases, the normal function ofthe nervous system has been altered, and

the patient is not in control of thealterations.


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THE CENTRAL NERVOUSSYSTEM

The CNS consists of the brain and thespinal cord, which share a continuous,protective, fibrous membrane cover calledthe meninges. The meninges consist ofthree separate membranes, which are

separated by spaces.


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Dura mater

Arachnoid Mater.

Pia mater


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Cerebrospinal Fluid

(1) Cerebrospinal fluid, circulating within thenetwork of the subarachnoid space, provides the

brain and spinal cord with protection. It acts as acushion, or shock-absorber, against injury.

(2) CSF is manufactured from blood in networksof capillaries called choroid plexuses. It

circulates through the ventricles (cavities insidethe brain) and subarachnoid space of themeninges.


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THE BRAIN

The human brain has three major subdivision:

Brainstem- Is the basal portion of the

brain.

Cerebellum __Is a spherical mass of nervoustissue attached to and covering the

hindbrainstem Cerebrum__ Is the largest part of the brain.


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Human Brain.


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The brainstem.


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THE SPINAL CORD

The spinal cord, located within the vertebral canal of thespine, is continuous with the brainstem. The spinal cordextends from the foramen magnum of the skull to thelevel of the first lumbar vertebrae, at which point it tapers

to fine threads of tissue. b. The spinal cord has two enlargements along its length

that are due to an increase in the mass of nervous tissuerequired to serve the limbs.

(1) The cervical enlargement is associated with the

nerves of the upper extremities. (2) The lumbosacral enlargement is associated with the

nerves of the lower extremities.


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The Spinal cord: cross-section.


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A very narrow canal, called the central canal, is located in thecenter of the spinal cord. This central canal is continuous with thefourth ventricle of the brain and contains CSF.

The processes of the neurons that compose the surrounding whitematter are grouped into pathways called fiber tracts.

(1) Tracts conducting impulses from the brain are called motortracts.

(2) Tracts conducting impulses to the brain are called sensory tracts. (3) At some specific point along the neuraxis, these pathways cross

to the opposite side of the cord and continue their path. (Eachcrossing is called a decussation.) Thus, the right cerebralhemisphere of the brain communicates with the left half of the body,and the left cerebral hemisphere communicates with the right half ofthe body.


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THE PERIPHERAL NERVOUSSYSTEM

Connecting the CNS to all parts of thebody are nerves. A nerve is a collection ofneuron processes, grouped together, and

located outside of the CNS. (Neuronprocesses, grouped together, and insidethe CNS are the fiber tracts of the spinalcord.) Nerves outside the CNS are

referred to as peripheral nerves, or thePNS. These nerves connect the CNS tothe periphery of the body.


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(1) Peripheral nerves connected to thebrainstem are called cranial nerves. They arenumbered from I through XII and have individualnames.

(2) Peripheral nerves connected to the spine arecalled spinal nerves. They are identified by aletter, representing the corresponding region ofthe vertebral column, and a numberrepresenting the sequence within the region. Forexample, L-5 is the fifth spinal nerve in thelumbar region.


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THE CRANIAL NERVES

a. Olfactory Nerve (I).

(1) Sensory nerve.

(2) Transmits smell impulses from receptors inthe nasal mucosa to the brain.

b. Optic Nerve (II).

(1) Sensory nerve. (2) Transmits visual impulses from the eye to the

brain.


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c. Oculomotor Nerve (III).

(1) Motor nerve.

(2) Contracts the eyeball muscles.

d. Trochlear Nerve (IV).

(1) Motor nerve.

(2) Contracts the eyeball muscles.

e. Trigeminal Nerve (V).

(1) Mixed nerve.

(2) Transmits pain, touch, and temperature impulsesfrom the face and head to the brain (sensory function).

(3) Contracts the muscles of chewing (motor function).


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f. Abducens Nerve (VI).

(1) Motor nerve.

(2) Contracts eyeball muscles.

g. Facial Nerve (VII). (1) Mixed nerve.

(2) Transmits taste impulses from the tongue tothe brain (sensory function).

(3) Contracts the muscles of facial expressionand stimulates secretion of salivary and lacrimalglands (motor function).


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h. Vestibulocochlear Nerve (VIII).

(1) Sensory nerve.

(2) Transmits hearing and balance impulses from theinner ear to the brain.

i. Glossopharyngeal Nerve (IX).

(1) Mixed nerve.

(2) Transmits taste impulses and general sensationsfrom the tongue and pharynx (sensory function) to the

brain. (3) Contracts the swallowing muscles in the pharynx and

stimulates secretions of the salivary glands.


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j. Vagus Nerve (X). (1) Mixed nerve. (2) Transmits sensory impulses from the viscera (heart, smooth

muscles, abdominal organs), pharynx, and larynx to the brain. (3) Secrets digestive juices, contracts the swallowing muscles of the

pharynx and larynx, slows down the heart rate, and modifiesmuscular contraction of smooth muscles. k. Spinal Accessory Nerve (XI). (1) Mixed nerve. (2) Transmits sensory impulses from the pharynx and larynx to the

brain.

(3) Contracts the muscles of the pharynx, larynx, and the neck. l. Hypoglossal Nerve (XII). (1) Motor nerve. (2) Contracts the muscles of the tongue.


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THE SPINAL NERVES

a. There are 31 pairs of spinal nerves,identified as follows:

(1) Cervical nerves (8) (C-1 through C-8).

(2) Thoracic nerves (12) (T-1 through T-12).

(3) Lumbar nerves (5) (L-1 through L-5). (4) Sacral nerves (5) (S-1 through S-5).

(5) Coccygeal nerve (1).


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Spinal nerve.


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In the human body, every spinal nervehas essentially the same structure andcomponents. By learning the anatomy of

one spinal nerve, you can understand theanatomy of all spinal nerves. Like a tree, atypical spinal nerve has roots, a trunk, and

branches.


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NERVE ACTION

a. A stimulus acts upon a sensory receptor. Theinformation is carried by an afferent (sensory)neuron through the merging branches of the spinalnerve that has been affected. The information iscarried through the posterior root ganglion and

posterior root to the spinal cord. Once theinformation reaches the spinal cord, it ascends theappropriate fiber tract to the designated area of thebrain.

b. Motor information (commands) from the brain will

descend along the appropriate fiber tract within thespinal cord until the appropriate spinal nerve isinnervated. The efferent (motor) neurons carry thecommand from the spinal cord to the effector organ.


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REFLEX ARC

The simplest reaction of the humannervous system is the reflex. A reflex is anautomatic reaction to a stimulus. The

pathway from the receptor organ to thereacting muscle is called a reflex arc(figure 2-5). The pathway of a reflex arc

contains five components.


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Reflex arc.


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a. The stimulus is received by a receptor organspecific to that stimulus.

b. The information is transmitted to the CNS by theafferent neuron of the appropriate peripheral nerve.

c. Within the spinal cord, the afferent neuronsynapses with a special connecting neuron called theinternuncial neuron (or interneuron).

d. In turn, the internuncial neuron synapses with theefferent neuron's cell body. The axon of the efferentneuron carries the information to the effector organ.

e. The effector organ receives the command to act.


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THE AUTONOMIC NERVOUSSYSTEM

a. The ANS is the portion of the nervous systemconcerned with innervation of smooth muscle, cardiacmuscle and the glands. The ANS regulates visceralactivities such as:

(1) Respiration. (2) Gastrointestinal motility. (3) Glandular secretion. (4) Contraction of smooth muscles.

(5) Constriction and dilation of the pupils. (6) Constriction and dilation of the blood vessels. (2)

Rate and force of cardiac muscle contraction.


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Neurological Assessment

11. Introduction12. Vital Signs13. Mental Status

14. Sensory Function15. Motor Function16. Level of Consciousness
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INTRODUCTION

A thorough neurological assessment isone that accurately and completelyevaluates the patient's:

vital signs

mental status

sensory function, motor function, and

level of consciousness.


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VITAL SIGNS

Vital signs should include:

Blood pressure.

Apical heart rate and rhythm. Radial pulses, bilaterally.

Femoral pulses, bilaterally.

Respiratory rate and rhythm. Temperature.


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Vital signs should be evaluated as follows:

Compare current vital signs with baseline andprevious vital signs.

Note any changes in pulse rate or rhythm. Note respiratory changes.

Note temperature elevations.

Note elevation of blood pressure, especiallywhen it occurs with a widening pulse pressure.


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MENTAL STATUS

Mental status assessment should evaluatethe following areas: State ofconsciousness.

Orientation.

Affect. (Mood)

Memory.

Cognition.


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TERMS-(SOC)

(1) Conscious (alert)--the patient responds immediately,fully, and appropriately to visual, auditory, and otherstimuli.

(2) Somnolent--unnatural drowsiness. The patient can bearoused and will respond to commands, but will fallasleep again as soon as he is left alone.

(3) Stuporous--partial unconsciousness. The patient canbe aroused with painful stimuli and will attempt torespond with purposeful withdrawal from the stimulus.

The patient may be restless or combative as well. (4) Comatose--complete unconsciousness, no

purposeful response to any stimulus.


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ORIENTATION

Orientation is determined by questioning the patientabout person, place, and time.

(1) Ask the patient to spell his name, name his children,or recite his address. Does the patient know who he is?

Does the patient know who others are? (2) Ask the patient to tell you where he is. He may be

asked to name the hospital, city, state, and so on.

(3) Ask the patient to tell you the year, month, and time-of-day (mid-morning, late afternoon, and so forth). Donot ask for the date. This is a poor indication oforientation. Most people cannot tell you the exact datewhen questioned.


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AFFECT

. Affect, or mood, is evaluated by observing the patient's verbal andnonverbal behavioral responses for appropriateness. For example:

Does the patient laugh when talking about serious or sad subjects?Is the patient easily startled by loud noises?

Does the patient respond to stimuli in a normal manner?

Does the patient display excessive anger, fear, confusion, and soforth? e. Long and short term memory should be evaluated by asking

questions. (1) Discussing past events or questioning the patient about his

medical history will test his ability for remote recall (long-termmemory).

(2) Questions about daily events will test recent recall (short- termmemory). For example, ask the patient what he ate for breakfast thatmorning.


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COGNITION

Cognition is tested by asking the patient toperform calculations. For example, ask thepatient to count backward from 100 by 7s.


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CONT

Pupillary response is another sensoryfunction indicator. Evaluate:

(1) Size in millimeters (do not usesubjective terms such as dilated orpinpoint.)

(2) Equality in size of the pupils.

(3) Response to light


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MOTOR FUNCTION

Evaluate motor function by testing muscle strength,mobility, and coordination.

a. Position the patient comfortably so that you can

observe both upper and lower extremities. b. Beginning with upper extremities, ask patient to put

each joint (wrist, elbows, shoulders) through active rangeof motion.

(1) Observe smoothness of movement. (2) Note inability to move any body part.

(3) Observe patient's facial expression for signs of anypain/discomfort.


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CONT

c. Extend your index and middle fingers ofeach hand and ask patient to grip firmly.

(1) Dominant hand will usually be slightlystronger.

(2) Note strength of both hands andcompare strength of one to the other


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CONT

d Instruct patient to put each lowerextremity joint (ankles, knees, hips)through active range of motion.

(1) Observe smoothness of movement.

(2) Note inability to move any body part.

(3) Observe patient's facial expression forsigns of any pain/ discomfort.


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CONT

e. Ask the patient to alternately flex andextend his feet while you provideresistance with your hands.

(1) Note the strength that the patientexerts against your resistance andcompare right to left.

(2) If muscle group is weak, lessen yourresistance or provide no resistance topermit more accurate observation.


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CONT

f. Observe coordination.

(1) Ask the patient to run his left heel along hisright shin (while standing) and vice versa.

(2) Ask the patient to close his eyes, extend hisarms, and touch his index finger to his nose.

(3) Ask the patient to walk in a straight line,forward and backward. Observe posture andbalance.


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LEVEL OF CONSCIOUSNESS

a The Glasgow Coma Scale (GCS) is a standardized,objective, reliable instrument for the assessment of levelof consciousness.

b. The scale measures three areas of observablebehavioral responses (verbal, motor, and eye). Patientresponses are graded by the degree of dysfunction. Thepatient's best response in each of the three areas isrecorded. The combined score of the three areas is the"consciousness level" score.

c. Recording and/or graphing the scores on a flow sheetpermits easy tracking of the patient's status.

)

S


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Response Scale(1) Eye response

(a) 4 points--eyes open spontaneously.

(b) 3 points--eyes open in response tosound.

(c) 2 points--eyes open in response topainful stimuli.

(d) 1 point--eyes do not open in responseto any stimuli.


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(2). Verbal response

5 points--the patient is oriented to person,place, and time.

(b) 4 points--the patient is confused but is able tocommunicate.

(c) 3 points--the patient speaks in a disorganizedmanner. (Inappropriate speech.)

(d) 2 points--the patient's response is moaningor groaning sounds. (Incomprehensible sounds.)

(e) 1 point--the patient does not respond.


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(3). Motor response

(a) 6 points--the patient obeys commands appropriately and movesall extremities equally and spontaneously.

(b) 5 points--the patient "localizes" to the stimulus (pain). Attempts tolocate the source of the pain and move the limb away from thestimulus.

(c) 4 points--the patient attempts to withdraw from the source of the(painful) stimuli in a less than purposeful movement. (Flexorwithdrawal.)

(d) 3 points--the patient flexes an extremity abnormally. (Decorticateresponse.)

(e) 2 points--the patient extends an extremity abnormally.(Decerebrate response.)

(f) 1 point--the patient has no motor response. (Flaccid.)


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Abbreviated Response Scale.

Eye Opening

SpontaneousTo soundTo pain

432

1


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Diagnostic Procedures

Skull X-Rays

Lumbar Puncture

Electroencephalogram

Brain Scan

Cerebral Angiography


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Skull X-Rays

Skull X-rays are the oldest, non-invasiveneurological test used to evaluate thebones, which make up the skull. Because

of complex anatomy of the skull, a seriesof films is usually required for a completeevaluation.

b. Diagnostic uses for skull X-rays:

(1) To detect fractures in patient's withhead trauma.
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CONT

(2) To help detect and assess increasedintracranial pressure, tumors, bleeding,and infection.

(3) To aid diagnosis of pituitary tumors.

(4) To detect congenital anomalies.

N i i li ti


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Nursing implications.

(1) Approach and identify the patient.

(2) Explain purpose in a manner consistentwith that offered by the physician.

(3) ) Patient is not required to restrict foodand fluids before x-rays unless orderedby the physician.

(4) Accompany patient to the department.

LUMBAR PUNCTURE


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LUMBAR PUNCTURE

Definition:

Is the insertion of a sterile needle into thesubarachnoid space of the spinal canal, usually

between the third and fourth vertebra, to reachthe cerebral spinal fluid. This test requires steriletechnique and careful patient positioning. It isperformed therapeutically to administer drugs or

anesthetics and to relieve intracranial pressure.


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Diagnostic uses for LP

(1) To determine the pressure of the cerebralspinal fluid.

(2) To detect increased intracranial pressure. (3) To detect presence of blood in the cerebral

spinal fluid which indicates cerebralhemorrhage.

(4) To obtain cerebral spinal fluid specimens forlaboratory analysis.


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CONT

(3) Approach and identify the patient.

(4) Interview the patient to determine his/herknowledge of the purpose of the LP procedure.

(5) As indicated, explain to the patient thespecific purpose of the LP procedure. Explainpurpose in a manner consistent with that offeredby the physician to avoid confusing the patient.

(6) Explain the procedure to the patient.

Proced re


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Procedure.

(1) Ask the patient to empty his/her bladder. (2) Position the patient. (a) Lateral recumbent, at the edge of the bed, knees drawn up to

abdomen, and chin tucked to chest. (b) To help the patient maintain this position, the nursing

paraprofessional places one hand behind the patient's neck and theother behind patient's knees to help support the patient's positionthroughout the procedure.

(3) The physician will clean the puncture site area with sterileapplicators from the lumbar puncture tray.

(4) The physician will drape the area with a fenestrated drape toprovide a sterile field.

(5) The physician will inject local anesthetic into the planned needlepuncture site.

(6) The physician will insert the spinal needle. The patient will feelsome pressure at this time.


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CONT

(7) When the needle is in place, the fluidwill drain from the needle hub into fourcollection tubes.

(8) When there is approximately 2 or 3 mlof fluid in each tube, the physician willhand them to the assistant, who will markthe tubes in sequence, stopper them

securely, and label them properly, assuch:

CONT


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CON T

(a) Gram stain.

(b) Culture, sensitivity.

(c) Cell count.

(d) Protein and glucose.

(9) The physician will remove the spinalneedle, apply pressure to the area briefly,

and apply a band-aid or small dressing. (10) The entire procedure will last

approximately 15 minutes.


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CONT

(1) Send the CSF specimens to the laboratoryimmediately.

(2) Instruct the patient to lie flat for 6 to 8 hoursor as directed by the physician to reduce chanceof headache.

(3) Monitor the patient carefully following theprocedure. Adverse reactions includingheadache, vertigo, syncope, nausea, tinnitus,respiratory distress, change in vital signs (TPR&B/P) and fever should be reported to theprofessional nurse.


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BRAIN SCAN


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BRAIN SCAN

a. Is the use of a specialized camera to provide imagesof the brain after an I.V. injection of a radionucleotide.Normally, the radionucleotide cannot permeate theblood-brain barriers, but if pathologic changes havedestroyed the barrier, the radionucleotide mayconcentrate in the abnormal area.

b. Diagnostic uses:

(1) To detect an intracranial mass or vascular lesion.

(2) To locate areas of ischemia, cerebral infarction, or

hemorrhage. (3) To evaluate the course of certain lesions

postoperatively and during chemotherapy.


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Nursing implications

Same as of LP procedure.

Patient will be kept nil by mouth for 6hours prior to the procedure.


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Care of the Unconscious Patient.

General

Airway and Breathing

Nutritional Needs

Skin Care

Elimination

Positioning


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GENERAL

(A). Unconsciousness means that the patient isunaware of what is going on around him and isunable to make purposeful movement. The

basic principle to remember is that theunconscious patient is completely dependent onothers for all of his needs. Any omissions inbasic nursing care or any failure to protect theunconscious patient in his helpless state may

inhibit recovery or greatly prolong hisconvalescence because of complications thatmight have been prevented.


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CAUSES

b. The most common causes of prolongedunconsciousness include:

(1) Cerebrovascular accident (CVA).

(2) Head injury.

(3) Brain tumor.

(4) Drug overdose.


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General nursing considerations:

(1) Always assume that the patient canhear, even though he makes no response.

(2) Always address the patient by name

and tell him what you are going to do.

(3) Refrain from any conversation aboutthe patient's condition while in the patient's

presence.


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d. Regularly observe and record the patient's vital signsand level of consciousness.

(1) Always take a rectal temperature.

(2) Report changes in vital signs to the team leader or

physician. (3) Note changes in response to stimuli.

(4) Note the return of protective reflexes such as blinkingthe eyelids or swallowing saliva.

e. Keep the patient's room at a comfortable temperature.Check the patient's skin temperature by feeling theextremities for warmth or coolness. Adjust the roomtemperature if the patient's skin is too warm or too cool.

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