Neurologic Exam Flashcards
cranial nerves
- 12 pairs emerging from base of brain (mainly brainstem) within the skull
- Motor, sensory or specialized functions
- Symptoms specific to area and function of nerve
- CN deficits can be due to nerve or brain lesions
- CN are technically peripheral nerves even though they come out of the brain
spinal cord
- Extends from medulla (brainstem) to L1-2
- Becomes cauda equina below L2
- Contains motor and sensory nerve pathways
- Mediates reflex activity of deep tendon reflexes
- Spinal nerves form from anterior and posterior nerve roots from spinal cord and combine with fibers from other levels in plexuses outside the cord, forming peripheral nerves
- Sensory (afferent) and motor (efferent) fibers
spinal nerves
- Connect spinal cord with muscles and peripheral sensory receptors
- Nerve roots exit vertebral (spinal) column through neural foramina
- Each spinal nerve has an anterior (motor) and a posterior (sensory) root
neural pathways
- Three Main “Super-Highways” of brain and spinal cord
- -Corticospinal Tract
- –Motor
- -Spinothalamic Tract
- –Sensory
- -Posterior Column
- –Sensory
- Primarily located in brainstem and spinal cord
corticospinal tract
- White matter connection between cerebral cortex and medulla in the anterior horn cells of the spinal cord
- -Motor pathway
- Responsible for muscle tone and skilled, voluntary movements
- Damage causes upper motor neuron symptoms
- -Spasticity, brisk reflexes, positive Babinski
- When UMN systems are damaged above the crossover of its tracts in the medulla, motor impairment develops on the contralateral (opposite) side; in damage below the crossover, motor impairment occurs on the ipsilateral (same) side of the body.
locating the source of motor deficits
- If corticospinal tract damaged or destroyed, motor function is affected below the level of injury
- If neurons are damaged above crossover tracts in medulla, motor impairment is on opposite (contralateral) side
UMN or LMN
- UMN problem (CNS to cord)
- -Affected extremity is spastic
- -Increased muscular tone
- -Increased reflexes
- LMN problem (CNS to peripheral nerve)
- -Affected extremity is flaccid
- -Decreased muscular tone
- -Decreased reflexes
- Upper motor neurons lie in motor strip of cerebral cortex and brainstem nuclei; axons synapse with motor nuclei in brainstem (CN) and spinal cord (peripheral nerves)
- Lower motor neurons have cell bodies in spinal cord (anterior horn cells); axons transmit impulses through anterior roots and spinal nerves into peripheral nerves, terminating at neuromuscular junction
spinothalamic tract
- Transmits pain, temp, and crude touch sensation from spinal cord to thalamus
- Fibers cross to contralateral side in cord and travel up
- Lesions cause contralateral anesthesias
- -Loss of pain
- -Loss of temperature
- Crude touch is a sensation perceived as light touch but without accurate localization
posterior columns
- Transmit fine touch, vibration, and proprioception from spinal cord to thalamus
- Fibers cross to contralateral side in the medulla
- Fine touch: touch that is accurately localized and finely discriminating
- Proprioception: position sense; this pathway is assessed with the Romberg test
- stereognosis assessed in this column: ability to recognize an object in your hand
- Specialized touch
- -These don’t cross until the medulla whereas spinothalamic tract cross over in the spinal cord section
motor exam
- (corticospinal tract) – combined with MSK system
- Myotomes (peripheral nerves to muscles)
- Body position at movement and rest
- Involuntary movements: tremors, tics, fasciculation
- Muscle bulk: atrophy
- Muscle tone: rigidity to passive ROM, spasticity, cog wheeling
- Muscle strength: resistive ROM
sensory exam
- Dermatomes (spinal nerves)
- Deep tendon reflexes (spinal reflexes)
- Sensation (spinothalamic tract, posterior columns)
cerebellum exam
balance & coordination
Biceps flexion innervation
C5 C6
Triceps extension innervation
C6 C7 C8
Grip innervation
C7 C8 T1
Hip flexion innervation
-iliopsoas
L2 L3 L4
Hip adduct innervation
L2 L3 L4
Hip abduct innervation
L4 L5 S1
Hip extend innervation
L2 L3 L4
Knee extend innervation
-quadriceps
L2 L3 L4
Knee flex innervation
-hamstrings
L4 L5 S1
Dorsiflex innervation
L4 L5
Plantarflex innervation
S1
Atrophy of the thenar eminence
may suggest median nerve damage
atrophy of hypothenar
may be ulnar nerve damage
sensory receptors found in
- Skin
- Mucous membranes
- Muscles, tendons
- Viscera
Sensory function
- Skin receptors for different kinds of sensation send afferent impulses to spinal cord via peripheral and spinal nerves
- Impulses travel via spinothalamic tract or posterior columns to thalamus
- Impulses then travel to cortex for fine interpretation
Dermatomes
- A dermatome is a band of skin innervated by the sensory root of a single spinal nerve
- Locating abnormal sensation to a dermatome identifies location of injury
Important dermatome levels
*T4 = nipple
*T10 = umbilicus
*C6 = thumb
C8 = ulnar side of handL4 = knee and medial maleolus
*S1 = lateral maleolus
S2 = heel
L5 = between big toe and little toe
Dermatomes start from embryology
spinal reflexes: deep tendon response
- Involuntary reflex arc between afferent and efferent nerves in spinal cord
- -Sensory impulse directly stimulates motor fiber
- Reflex – involuntary stereotypical response
- Each reflex involves specific spinal segment – abnormal finding will be helpful in location of problem