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What are the 4 regions of the brain?
What are the lobes that each brain hemisphere is divided into?
Cortex controls higher mental functions, general movement, visceral functions, perception, behavior, and integration of these functions.
Aids cerebral cortex in the integration of voluntary movement, processes sensory info from the eyes, ears, touch receptors, and the musculoskeletal system.
The pathway between the cerebral cortex & spinal cord, controls many involuntary function, nuclei of the 12 cranial nerves arise from here.
What encases the spinal cord? Where does it terminate? How many segments are in the spinal cord?
- bony vertebral column
- L1 or L2 vertebrae
- 5 segments
Where do the 12 pairs of cranial nerve emerge from?
within the cranium
Which nerves carry impulses to and from the spinal cord? How many pairs are there?
- peripheral nerves
- 31 pairs (C8, T12, L5, S5, C1)
What is contained within the anterior and posterior roots of peripheral nerves?
- anterior (ventral): MOTOR fibers
- posterior (dorsal): SENSORY fibers
What forms the spinal nerves? How long are they?
- each peripheral nerve root merges to form the spinal nerve
- less than 5 mm long
Spinal nerves comingle with similar fibers from other levels in ________ outside the cord from which ________ nerves emerge.
Peripheral nerves contain both ______ and ______ fibers.
Where do nerve cell bodies of UMNs lie?
in the motor strip of the cerebral cortex
What do the axons of UMNs synapse with to pass signals to LMN cell bodies that transmit impulses through ventral roots & spinal nerves into peripheral nerves?
motor nuclei in the brainstem and spinal cord which then synapse with LMN cell bodies
What are the principle motor pathways of the spinal cord & brainstem?
- corticospinal tract
- corticobulbar tract
Which motor pathway crosses the spinal cord in the medulla?
Where will motor impairment develop when a UMN in the corticospinal tract is damaged above the crossover? What if it is damaged below the crossover?
- contralateral side (above)
- ipsilateral side (below)
If muscle tone is increased and DTRs are exaggerated what is damaged?
If muscle tone and DTRs are absent what is damaged?
Impulses from skin, mucous membranes, muscles, tendons, and viscera are relayed through ______ and _______ into the spinal cord.
- peripheral nerves
- dorsal roots
What are the two sensory pathways that carry input from the spinal cord to the sensory cortex in the brain?
- spinothalamic tracts
- posterior columns
What does the pattern of sensory losses together with motor losses help identify?
where the causative lesion might be
What sensations does a lesion of the sensory cortex impair? How does this affect a person?
- finer discrimination (may not impair perceptions of pain, touch, position)
- w/out finer discrimination a person cannot appreciate the size, shape or texture of an object by feeling it and cannot identify it
What does loss of position and vibration sense with preservation of other sensations indicate?
disease of the posterior columns
What does loss of all sensations from the waist down, together with paralysis & hyperactive DTRs in the legs indicate?
transection of the spinal cord
What sensations synapse with secondary neurons and then cross to the opposite side and pass upward in the spinothalamic tract into the thalamus?
- crude touch
What sensations pass directly into the posterior columns of the cord and travel upward to the medulla where they synapse with secondary neurons and cross to the opposite side and continue to the thalamus?
- fine touch
At what level is general sensation perceived (pain, cold, pleasant, etc) but fine distinctions are not made? What is needed for full perception?
- thalamic level
- a third group of neurons that send impulses to the sensory cortex of the brain where stimuli are localized & higher order discriminations are made
When does general assessment of mental status begin?
when first meeting the patient
What is included in the general assessment of mental status?
- level of consciousness (alert & oriented?)
- general appearance (posture, behavior, dress, hygiene)
- affect (external expression of inner emotional state)
Reflects pt's capacity for arousal, is determined by the level of activity that the pt can be aroused to perform in response to escalating stimuli.
What are the 5 levels of consciousness?
- alert: speak in normal voice, pt opens eyes, looks at you, responds fully and appropriately
- lethargic: speak in loud voice, pt appears drowsy but opens eyes and looks at you, responds to questions and then falls asleep
- obtunded: shake pt gently, pt opens eyes & looks at you but responds slowly and is confused; alertness and interest are decreased
- stuporous: apply painful stimulus (sternum rub, pencil roll over nail), pt arouses from sleep only after painful stimuli; verbal responses slow & pt lapses back into sleep
- coma: apply repeated stimuli, pt remains unarousable with eyes closed
How do you determine a pt's mental orientation?
- time: day, week, month, season, date & year, duration of hospitalization
- place: pt's residence, name of hospital, city, state
- person: pt's own name, relative's & personnel names
- **ask DIRECT questions**
How would you evaluate long term memory while testing cognitive functions?
ask about well known distant events (last 3 presidents in order)
How would you evaluate short term memory while testing cognitive function?
- give pt 3 unrelated words to remember
- have them repeat the words initially, then at 5-15 minutes (ie, car, purple, juice)
- **tests registration & immediate recall**
How would you assess intellectual function while testing cognitive function?
- instruct pt to count down from 100 by 7s
- may also give them a 5 letter word to spell, then have them do it backwards (ie, world)
Where do CN III-XII arise from?
diencephalon & brainstem
Where do CN I-II arise from?
brain (fiber tracts)
What impulses do the 12 cranial nerves provide?
- I: smell
- II: VA, visual fields, ocular fundi
- III: pupillary constriction; opening eyelid, most EOMs
- IV: downward & internal rotation of the eye
- V: corneal reflex, facial sensation, jaw movements
- VI: lateral deviation of the eye
- VII: facial movements & taste anterior tongue
- VIII: hearing & balance
- IX, X: swallowing, rise of palate, gag reflex; taste posterior tongue
- V, VII, IX, X, XII: voice & speech
- XI: shoulder & neck movements
- XII: tongue symmetry & position
What are some reasons that can cause a loss of the sense of smell?
- sinus conditions
- head trauma
- cocaine use
What do you do to examine the optic nerve (CN II)?
- test VA
- inspect optic disc for atrophy/papilledema
- test visual fields by confrontation
Testing the EOMs in the 6 cardinal directions of gaze, looking loss of conjugate movements in any of them (causes diplopia) tests which cranial nerves?
- III: oculomotor
- IV: trochlear
- VI: abducens
Involuntary jerking movement of the eyes with quick and slow components.
nystagmus (name for the direction of the quick component)
Drooping of the upper eyelid.
- 3rd nerve palsy (ptosis)
- **slight different in palpebral fissure width is normal in 1/3 of pts**
What cranial nerve causes the corneal reflex?
CN V (trigeminal)
What is the corneal reflex? How is it tested?
- have pt look up & away from you
- approach from the other side out of pt's line of vision, avoid eyelashes & touch the cornea lightly with cotton
- look for blinking of BOTH eyes (sensory CN V, motor CN VII)
- blinking will be absent with a CN V or VII lesion
What features on a pt's face suggest facial weakness?
- flattening of nasolabial fold
- drooping of lower eyelid
What type of nerve injury affects both the upper and lower face?
peripheral (Bell's palsy)
What type of nerve injury affects only the lower face?
central lesion (stroke)
If hearing loss is present when testing CN VIII (acoustic), how would you test further? Why is this important?
- Weber & Rinne
- distinguishes CHL vs SNHL
How is the motor division of CN IX (glossopharyngeal) and X (vagus) tested?
have pt say "ahh"; palate should rise symmetrically
What indicates paralysis of CN IX and X?
pulling of the uvula to the unaffected side
What does the gag reflex test?
both sensory & motor components of CN IX & X
What does unilateral absence of the gag reflex suggest?
- lesion of CN IX, perhaps CN X
- **unilateral lesion affecting vagus nerve can produce hoarseness & difficult swallowing due to loss of laryngeal function**
When testing CN XI (spinal accessory), what does trapezius weakness with atrohpy and fasciculations indicate?
peripheral nerve disorder
What does a drooping shoulder with a scapula that is displaced downward and laterally indicate?
trapezius paralysis (CN XI problem)
What direction will a protruded tongue move to in a pt with a unilateral cortical lesion?
AWAY from the side of the lesion (toward the side of weakness)
What part of the sensory system are you assessing with pain and temperature?
What part of the sensory system are you assessing with position and vibration?
What part of the sensory system are you assessing with light touch?
both spinothalamic tracts and posterior columns
What part of the sensory system are you assessing with discriminative sensations?
What are the dermatomal areas you should check at minimum?
- all 3 branches of CN V
- C5, C6, T1, T2, radial, ulnar, median
- T4 (nipple), T10 (umbilicus), T12 (iliac crest)
- L3, L4, L5, S1, saphenous, superficial peroneal
How is temperature sensation tested?
- two test tubes one with cold water, one with hot/ tuning fork heated or cooled by water
- **often omitted if pain sensation is normal**
If vibration sense is impaired what should you do?
move to more proximal bony prominences
What are some additional techniques used to assess discriminatory sensations?
- graphesthesia (number ID)
- 2-pt discrimination
- point location
Ability to identify an object by feeling it.
Used if stereognosis is too painful/difficult for the pt (arthritis, etc). Involves drawing a large number in pt's palm for them to identify.
Briefly touch a point on the pt's skin, have them open both eyes and point to the place touched.
What is the normal distance at which a person will still be able to discriminate feeling one from two points?
<5 mm on fingerpads
What are you observing when testing the motor system?
- body position (movement & rest)
- involuntary movements (tremors, tics, fasciculations; note location, quality, rate, rhythm, amplitude, relation to posture, activity, fatigue, emotion)
- muscle bulk (flat/concave=atrophy, unilateral/bilateral, proximal/distal)
What are the 5 upper extremity muscle groups that represent motor innervation by the cervical spinal cord?
- C5, biceps brachii: elbow flexion
- C6, ECRL/ECRB: wrist extension (radial)
- C7, triceps: elbow extension
- C8, finger flexors: finger flexion (grip) and thumb opposition (median)
- T1, interossei: little finger abduction (ulnar)
What are the 5 lower extremity muscle groups that represent motor innervation by the lumbosacral spinal cord?
- L2, psoas: hip flexion
- L3, quadriceps: knee extension
- L4, tibialis anterior: ankle dorsiflexion/inversion
- L5, hallucis longus: great toe extension
- S1, gastrocnemius: plantar flexion
For a DTR to fire all components of the reflex must be intact. What are the components?
- sensory nerve fibers
- spinal cord synapse
- motor nerve fibers
- neuromuscular junction
- muscle fibers
How does tapping a tendon activate the reflex response?
- special sensory fibers in the muscles are activated, triggering a sensory impulse that travels to the spinal cord via a peripheral nerve
- the stimulated fiber synapses directly with the ANTERIOR horn cell innervated the same muscle
- when the impulse crosses the neuromuscular junction, the muscle suddenly contracts, completing the reflex arc
What are the segmental levels of the DTRs for triceps, biceps, brachioradialis, patella, and achilles?
- triceps: C6, C7
- biceps: C5, C6
- brachioradialis: C5, C6
- patellar: L2, L3, L4
- achilles: S1
What are the segmental levels of cutaneous reflexes?
- abdominal upper: T8, T9, T10
- abdominal lower: T10, T11, T12
- plantar: L5, S1
- anal: S2, S3, S4
What is the grading scales for reflexes?
- 4+: very brisk with clonus
- 3+: brisker than average (high normal); possible disease
- 2+: average (normal)
- 1+: somewhat diminished (low normal)
- 0: no response
How are reflexes affected with CNS lesions along the descending corticospinal tract?
- they are hyperactive
- look for associated UMN findings of weakness, spasticity/positive Babinski
How are reflexes affected with diseases of spinal nerve roots, spinal nerves, plexuses, or peripheral nerves?
- they are hypoactive
- look for associated findings of LMN signs of weakness, atrophy & fasciculations
What causes an abnormal (positive) Babinski (plantar reflex) sign?
- CNS lesion in corticospinal tract
- unconscious states from drug/alcohol intoxication or postictal period follow a seizure
What does sustained clonus indicate?
What is a critical part of the spinal cord injury examination, particularly in trauma?
assessing anal sphincter tone (S2-S4)
What are the four areas of the nervous system that need to function in an integrated way for coordination of muscle movement?
- motor system (muscle strength)
- cerebellar system (rhythmic movement & steady posture)
- vestibular system (balance, eye, head & body movement)
- sensory system (position sense)
How do you assess coordination (cerebellar exam)?
- rapid alternating movements (RAMs)
- point to point movments (finger to nose, heel to shin)
- standing in specific ways (Romberg, pronator drift)
What is the term used to describe cerebellar disease that causes deficiencies in the rapid alternating movements test?
dysdiadochokineses: one movement cannot be followed quickly by its opposite and movements are slow, irregular and clumsy
How does a patient with cerebellar disease tend to perform during the the finger to nose test? What is the term used to describe the finger initially overshooting its mark?
- movements are clumsly, unsteady, and inappropriately varying in their speed, force & direction
- dysmetria (finger overshoots)
How does a patient with cerebellar disease tend to perform during the heel to shin test?
- heel may overshoot the knee, then oscillate from side to side down the shin
- when position sense is lost the heel is lifted too high & the pt tries to look
A gait that lack coordination with reeling and instability.
What can cause ataxia?
- cerebellar disease
- loss of position sense
Which gait test may reveal ataxia not previously obvious?
How does a pt with ataxia from dorsal column disease and loss of position sense perform on the Romberg test?
- vision compensates for sensory loss
- pt stands fairly well will eyes open but loses balance when they are closed (positive Romberg)
How does a pt with cerebellar ataxia perform on the Romberg test?
pt has difficulty standing with feet together whether eyes are closed or not
What is the pronator drift test sensitive and specific for?
corticospinal tract lesion originating in the contralateral hemisphere
What is a positive Brudzinski's sign? What is it looking for?
- flexion of hips and knees when neck is passively flexed
What is a positive Kernig's sign? What is it looking for?
pain & increased resistance to extending the knee after passively flexing pt's leg at the hip & knee (when bilateral it suggests meningeal inflammation; when unilateral suggests pain from lumbosacral nerve root compression)