Lecture 1 - Ortho neuro, professor lindor PDF

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Lecture 1 Structure and Function of the Nervous System  Responsible for the control and integration of the body’s many activities  Divided into 2 parts  Central Nervous System (CNS)  Brain  Spinal cord  Cranial Nerves I and II  Peripheral Nervous System (PNS)  Cranial nerves III to XII  Sp...

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Lecture 1  Structure and Function of the Nervous System  Responsible for the control and integration of the body’s many activities  Divided into 2 parts  Central Nervous System (CNS)  Brain  Spinal cord  Cranial Nerves I and II  Peripheral Nervous System (PNS)  Cranial nerves III to XII  Spinal nerves  Autonomic Nervous System (ANS) ○ Sympathetic ○ Parasympathetic  Cells of the Nervous System (2 Types)  Neurons  The primary functional unit of the nervous system  3 characteristics: ○ Excitability  generate a nerve impulse ○ Conductivity  transmit the impulse to other portions of the cell ○ Influence  influence other neurons, muscle cells, glandular cells by transmitting nerve impulses to them  Neuron consists of: ○ Cell body ○ Dendrites  Receive nerve impulses from the axons of other neurons  Conduct impulses toward the cell body ○ Axon  Carries nerve impulses away to other neurons or end organs  Many are covered by a Myelin Sheath  Acts as an insulator for the conduction of impulses  Surrounds and protects the axons  Formed by Schwann cells  Cover axons of certain neurons  Myelinated  white matter  Unmyelinated  gray matter  Nodes of Ranvier  Make the impulse travel faster from one neuron to the next  Glial Cells (glia / neuroglia)  4 basic functions ○ Provide structural support ○ Nourishment ○ Protection to neurons ○ Regulates fluids

 More numerous than neurons  Able to replicate  Nerve Regeneration  The neuron must be intact in order for an impulse to travel  If the axon of a nerve cell is damaged, it attempts to repair itself  Axons in the CNS (brain and spinal cord) cannot regenerate  In the PNS, injured nerve fibers can regenerate within the protective myelin sheath of the supporting Schwann cells  Only if the cell body is intact  The insult is always below the level of the injury  Nerve Impulse  The initiation of a neuronal message (nerve impulse) involves the generation of an action potential  Depolarization is needed to have an action potential ○ “Gates of the postsynaptic cell open up allowing the shift of K+ and Na+” ○ K+  lives inside the cell  Goes outside the cell during depolarization ○ Na +  lives outside the cell  Goes into the cell during depolarization ○ Depolarization – Relaxation – Repolarization  The action potential then travels along down the axon  Synapse  2 types ○ Electrical  Action potential moves from neuron to neuron ○ Chemical  Release of neurotransmitters when the action potential gets to the end of the axon  Presynaptic Terminal  Synaptic Cleft [space]  Postsynaptic Cell [new neuron]  Neurotransmitters  Chemicals released from neurons that stimulate electrical reaction in adjacent neurons  Excitatory neurotransmitters activate the postsynaptic receptors ○ But a presynaptic cell that releases an excitatory neurotransmitter does not always cause the postsynaptic cell to depolarize enough to generate an action potential  Inhibitory neurotransmitters inhibit the likelihood that an action potential will be generated  Examples of Neurotransmitters: ○ Acetylcholine  ↓ = Alzheimer’s disease, Myasthenia Gravis ○ Amines  Epinephrine  Norepinephrine

 Serotonin  Mood, Emotion, Sleep  Dopamine  Emotions, Moods, Motor Control,  ↓ = Parkinson’s ○ Amino Acids  GABA (most common inhibitory neurotransmitter)  Treat seizures  Glutamate (most common excitatory neurotransmitter) ○ Neuropeptides  Endorphins (inhibits pain)  Substance P (causes pain)  Ex. ○ GABA  Inhibitory  no muscle contraction ○ Glutamate  Excitatory  muscle spasticity ○ Need a balance of both  Central Nervous System  Spinal Cord  Gray matter contains the cell bodies; White matter contains the axons (because that is the part that is myelinated)  Ascending Tracts ○ Carry sensory information to the higher levels of the CNS ○ Afferent  Descending Tracts ○ Carry impulses that are responsible for muscle movement ○ Efferent  Upper Motor Neurons ○ Muscle spasticity, possible contractures ○ Little or no muscle atrophy, but ↓ strength ○ Hyperactive deep tendon and abdominal reflexes ○ Absent plantar reflex ○ No fasciculations ○ Damage above level of brainstem will affect the opposite side of the body ○ Paralysis of lower part of the face, if involved  Lower Motor Neurons ○ Muscle flaccidity ○ Loss of muscle tone and strength, muscle atrophy ○ Weak or absent deep tendon, plantar, and abdominal reflexes ○ Fasciculations ○ Changes in muscle supplied by that nerve  Usually a muscle on the same side as the lesion ○  Brain  Cerebrum ○ Frontal lobe

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 Primary motor area  Voluntary motor movements  Higher cognitive function  Memory retention  Voluntary eye movements  Broca’s area: expressive speech (output of language) ○ Temporal lobe  Primary auditory area  Wernicke’s area: receptive speech (understanding of spoken and written words)  Integration of somatic, visual, and auditory data ○ Parietal lobe  Primary sensory area  Receives and interprets nerve impulses from sensory receptors  Controlling and interpreting spatial information ○ Occipital lobe  Primary visual area ○ Thalamus  Relays sensory and motor input to and from the cerebrum ○ Hypothalamus  Regulates the ANS and endocrine system  Regulates temperature  Fluid regulation ○ Limbic System  Emotion  Aggression  Feeding behavior  Sexual response Brainstem ○ Connects the cerebral hemisphere with the spinal cord ○ Midbrain ○ Pons ○ Medulla ○ Responsible for respirations, BP, HR Cerebellum ○ Coordinate voluntary movement ○ Maintain trunk stability and equilibrium Ventricles and CSF ○ Ventricles are 4 fluid filled cavities within the brain that connect with the spinal canal ○ CSF circulates in the subarachnoid space that surrounds the brain, brainstem, and spinal cord  Provides cushioning for the brain and spinal cord  Allows fluid shifts from the cranial cavity to the spinal cavity  Carries nutrients

○ CSF is absorbed through the arachnoid villi, then goes into the venous system  Peripheral Nervous System  Spinal Nerves  Cranial Nerves  I – Olfactory  II – Optic  III, IV, VI – Ocularmotor, Trochlear, Abducens  V – Trigeminal  VII – Facial  VIII – Acoustic  IX, X – Glossopharyngeal, Vagus  XI – Accessory Muscles  XIII – Hypoglossal  Autonomic Nervous System  Governs involuntary functions of cardiac muscle, smooth (involuntary) muscle, and glands  Divided into 2 components that function together to maintain balance ○ Sympathetic – “fight or flight” ○ Parasympathetic – conserves and restores energy  Protective Structures  Meninges  3 layers of protective membranes that surround the brain and spinal cord ○ Dura mater  Outermost layer ○ Arachnoid mater  CSF is between the arachnoid layer and the Pia mater  CSF protects the spine and brain  Subarachnoid space ○ Pia mater  Innermost layer  Vascular  Skull  Vertebral Column  Made up of 33 individual vertebrae ○ 7 Cervical ○ 12 Thoracic ○ 5 Lumbar ○ 5 Sacral (fused into 1) ○ 5 Coccygeal (fused into 1)  Effects of Aging on the Nervous System  Loss of neurons occur in certain areas of the brainstem, cerebellum, and cerebral cortex

 It is a gradual process that begins in early adulthood  Loss of neurons lead to:  Widening/enlarging of the ventricles  Decreased brain weight  ↓ cerebral blood flow  ↓ CSF production  Cerebral atrophy  Pathologic abnormalities  In the PNS, degeneration of myelin  ↓ in nerve conduction  More likely to experience orthostatic hypotension  Coordinated neuromuscular activity such as the maintenance of BP gets altered with aging  Less able to adapt to extreme environmental temperatures  ↑ risk for hypo/hyperthermia  ↓ Memory, vision, hearing, taste, smell, vibration and position sense, muscle strength, and reaction time  Sensory changes  ↓ taste and smell perception  May lead to ↓ dietary intake  ↓ hearing and vision  Can result in perceptual confusion  Problems with balance and coordination  At risk for falls/fractures  Assessment of the Nervous System  Subjective Data  Important Health Information  Past Health History ○ Avoid suggesting certain symptoms and leading questions ○ We want to know the mode of onset and the course of the illness ○ If the patient is not a reliable historian, obtain the history from a person who knows the patient’s problems and complaints  Medications ○ Are they using any sedatives, opioids, tranquilizers, or moodelevating drugs ○ Many other drugs can cause neurologic side-effects  Surgery or Other Treatments ○ Have they had any surgery involving the nervous system  Head, spine, sensory organ (eyes, ears, nose, mouth) ○ If they did have surgery, determine the date, cause, procedure, recovery, and current status  Functional Health Patterns (pg. 1415 – box)  Health Perception/Health Management ○ Ask about health practices related to the nervous system

Substance abuse/Smoking Maintenance of adequate nutrition Safe participation in physical and recreational activities Use of seatbelts/helmets Control of hypertension Ask about previous hospitalizations for neurologic problem Careful family history  Determine whether the neurologic problem is hereditary or congenital  If the patient has an existing neuro problem, assess how it affects their daily living/self-care Nutritional/Metabolic ○ Problems related to chewing, swallowing, facial nerve paralysis, and muscle coordination can make it difficult for the patient to ingest adequate nutrients ○ Certain vitamins are essential for the maintenance and health of the CNS  Thiamine (B1), and B6 ○ Cobalamin (B12) deficiency is a risk for older adults  They tend to have problems with vitamin absorption from both supplements and food  If untreated  mental function decline Elimination ○ Bowel and bladder problems are often associated with neurologic problems (stroke, head injury, spinal cord injury, multiple sclerosis, dementia) ○ Determine if the bowel/bladder problem was present before or after the neurologic event to plan appropriate interventions ○ Nerve root compression leads to a sudden onset of incontinence ○ Careful documentation of the details of the problem  Number of episodes  Accompanying sensations or lack of sensations  Measures to control the problem Activity/Exercise ○ Many neurologic problems can cause problems in the patient’s mobility, strength, and coordination  These problems can result in changes in the patient’s usual activity and exercise patterns  Falls can also result from these problems ○ The ability to perform fine motor tasks may also be affected  This increases the possibility of personal injury Sleep/Rest ○ Discomfort from pain and the inability to move and change positions because of muscle weakness/paralysis can interfere with sleep quality       

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Cognitive/Perceptual ○ Assess memory, language, calculation ability, insight, and judgment  Many neurologic disorders affect these functions ○ Delirium: acute confusional state  May be seen at any time during a patient’s illness  Often an early indicator of various illnesses ○ Assess for appropriateness of responses ○ Careful assessment of the patient’s pain ○ Determine the patient’s understanding and ability to carry out necessary treatments  Self-Perception/Self-Concept ○ The patient’s physical and emotional control can be affected ○ Inquire about the patient’s self-worth, perception of abilities, body image, and general emotional pattern  Role/Relationship ○ Ask the patient if changes in roles have occurred resulting from the neurologic problem (spouse, breadwinner, parent) ○ Physical impairment can alter or limit participation in usual roles and activities  Sexuality/Reproductive ○ Many nervous system disorders can affect sexual response  Coping/Stress ○ Assess the patient’s usual coping pattern to determine if coping skills are adequate to meet the stress of a problem ○ Assess the patient’s support system  Value/Belief ○ Determine if any religious/cultural beliefs could interfere with the planned treatment regimen  Objective Data  Physical Examination  Mental Status (cerebral functioning) ○ Much of the mental status exam can be assessed as you interact with the patient  General appearance and behavior  LOC (awake, asleep, comatose)  Motor activity  Body posture  Dress and hygiene  Facial expression  Speech  Cognition  Orientation to person, place, time, and situation  Memory  General knowledge  Insight 

Judgment Problem solving Calculation  Who were the last 3 presidents?  Subtract 7 from 100 and keep subtracting 7  Mood and affect  Note any agitation, depression, or euphoria Cranial Nerves ○ Olfactory Nerve  Make sure both nostrils are patent  Ask the patient to close one nostril and sniff a readily recognized odor  With their eyes closed  The same is done for the other nostril  Things that can ↓ the sense of smell  Rhinitis  Sinusitis  Heavy smoking  Disturbance in the ability to smell may be associated with  A tumor involving the olfactory bulb  Basilar skull fracture that has damaged olfactory fibers ○ Optic Nerve  Assess visual fields and acuity  Visual fields  Ask the patient to look directly at the bridge of your nose and indicate when an object presented from the periphery of each visual field is seen  Finger/Pencil tip  Visual field defects may arise from  Lesions of the optic nerve  Optic chiasm  Tracts that extend through the temporal, parietal, or occipital lobes  Visual acuity  Test visual acuity by having the patient read a Snellen chart from 20 feet away ○ Oculomotor, Trochlear, and Abducens Nerves  All these nerves help to move the eye, so they are tested together  Ask the patient to follow your finger as it moves horizontally and vertically  Disconjugate gaze  Weakness or paralysis of one of the eye muscles  Eyes do not move together  Nystagmus  Fine, rapid, jerking movements of the eyes   

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 Check for pupillary constriction and accommodation  Oculomotor nerve (CN III)  Shine a light into the pupil of one eye  The lack of pupillary constriction is a sign of central herniation  Check for convergence and accommodation  Have the patient focus on your finger as it moves toward the center of their nose ○ Trigeminal Nerve  Have the patient identify light touch and pinprick in each of the 3 divisions on both sides of the face  The patients eyes should be closed  Have the patient clench their teeth then palpate the masseter muscles  Corneal reflex  Evaluates CN V and VII simultaneously  Assess the blink-to-threat in the unconscious patient ○ Facial Nerve  Muscles of facial expression  Ask the patient to  Raise their eyebrows  Close eyes tightly  Purse the lips  Smile  Frown  Note any asymmetry in the facial movements  Can indicate damage to the facial nerve ○ Acoustic Nerve  Have the patient close their eyes and indicate when a ticking watch or rustling of the examiners fingers are heard ○ Glossopharyngeal and Vagus Nerves  These are tested together because they both innervate the pharynx  Test the gag reflex  Touch either side of the posterior pharynx with a tongue blade  If the reflex is weak/absent  danger of aspirating food/secretions  Note the symmetry of the soft palate ○ Accessory Nerve  Ask the patient to shrug their shoulders and to turn their head from side to side ○ Hypoglossal Nerve  Ask the patient to protrude the tongue  Should be midline Motor System

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○ Assess strength, tone, coordination, and symmetry of the major muscle groups ○ Ask the patient to push/pull against the resistance of your arm ○ Same with the shoulders, elbows, wrists, hips, knees, and ankles ○ Pronator drift  Downward drifting of the arm  Mild weakness of the arm ○ Note any weakness or asymmetry of strength ○ Test muscle tone by passive ROM  There should be a slight resistance  Abnormal tone:  Hypotonia (flaccidity)  Hypertonia (spasticity ○ Observe the patient’s stature and gait  Note the pace and rhythm  Observe the arm swing ○ Assess balance and coordination  Finger to nose test  Have the patient alternately touch the nose, then touch the examiner’s finger  Heel to shin test  Have the patient stroke the heel of one foot up and down the shin of the opposite leg  Ask the patient to pronate and supinate both hands rapidly  Ask the patient to do a shallow knee bend, first on one leg and then on the other ○ Dysatharia or slurred speech should be noted  It is a sign of incoordination of the speech muscles Sensory System ○ Perform the examination with the patient’s eyes closed ○ Avoid providing the patient with clues  Ask “How does this feel?” instead of “Does this feel sharp?” ○ Touch, Pain, and Temperature  Light touch is usually tested first  Gently stroke a cotton wisp over each of the four extremities  Ask the patient to indicate when the stimulus is felt by saying “touch”  Test pain by touching the skin with the sharp end of a pin  The sensation of temperature can be tested by applying tubes of warm and cold water to the skin  Ask the patient to identify the stimuli with their eyes closed ○ Vibration Sense

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 Apply a vibrating tuning fork to the fingernails and the bony prominences of the hands, legs, and feet  Ask the patient if the vibration or “buzz” is felt  Then ask the patient when the vibration ceases ○ Position Sense  Place your thumb and forefinger on either side of the patient’s forefinger or great toe  Gently move the finger up and down  Ask the patient to indicate the direction in which the digit is moved  Romberg Test  Ask the patient to stand with their feet together and then close their eyes  If the patient is able to maintain balance with their eyes open, but sways or falls with their eyes closed  Positive Romberg test  Vestibulocochlear dysfunction  Disease in the posterior columns of the spinal cord ○ Cortical Sensory Function  Two point discrimination  Graphesthesia  Ability to feel writing on the skin  Have the patient identify numbers traced on the palm of the hands  Stereognosis  Able to perceive the form and nature of objects  Have the patient identify the size and shape of easily recognized objects (coins, keys, safety pin) Reflexes ○ 0/5 – absent ○ 1/5 – weak response ○ 2/5 – normal response ○ 3/5 – exaggerated response ○ 4/5 – hyperreflexia with clonus  Clonus  An abnormal response  Continued rhythmic contraction of the muscle with continuous application of the stimulus ○ Biceps  Place the thumb over the biceps tendon in the antecubital space  Strike the thumb with a hammer  The patient should have the arm partially flexed at the elbow with the palms up  Normal response  Flexion of the arm at the elbow

Contraction of the biceps muscle that can be felt by the thumb Triceps  Strike the triceps tendon above the elbow while the patient’s arm is flexed  Normal response  Extension of the arm  Visible contraction of the triceps Brachioradialis  Strike the radius 3-5 cm above the wrist while the patient’s arm is relaxed  Normal response  Flexion and supination at the elbow  Visible contraction of the brachioradialis muscle Patellar  Strike the patellar tendon just above the patella  The patient can be sitting or lying  Just as long as the leg being tested hangs freely  Normal response  Extension of the leg  Contraction of the quadriceps Achilles tendon  Strike the Achilles tendon while the patient’s leg is flexed at the knee and the foot is dorsiflexed at the ankle  Normal response  Plantar flexion at the ankle 

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 Diagnostic Studies of the Nervous System  Cerebral Spinal Fluid Analysis  Lumbar Puncture  CSF is aspirated by needle insertion ○ Into the subarachnoid space of the spinal canal ○ Between L3-4 and L4-5  For diagnostic or therapeutic reasons  To assess many CNS diseases  Inject air, dye, or drugs into the spinal canal  Contraindications ○ Presence of ↑ ICP ○ Infection at the site of the puncture compression ○ Ensure that the patient has no cerebral tumor before the start of the procedure  Could result in herniation ...