Neuro-physiology basics

Question	Answer
Myotatic reflex stimulus	muscle stretch
Myotatic reflex arc	Afferent Ia from muscle spindle to alpha MN and back to muscle
Myotatic reflex function	maintenance of muscle tone, support agonsist muscle contraction, provide feedback about muscle length
Myotatic reflex testing	DTR
Via an inhibitory IN the myotatic reflex inhibits the antagonist	Reciprocal inhibition
Myotatic reflex effect on synergistic muscles	facilitation
Inverse myotatic reflex stimulus	muscle contraction
Inverse myotatic reflex arc	Afferent Ib from GTO via inhibitory IN to muscle
Function of inverse myotatic reflex arc	provides agonist inhibition, decreases force of agonist, stretch protection reflex
Allows muscle tension to come under control of descending pathways	Gamma reflex loop
Gamma reflex loop path	excite gamma MN causing muscle spindle contraction then increased stretch sensitivity and increased firing from spindle afferents then conveyed to alpha MNs
Flexor withdrawal reflex stimulus	cutaneous sensory stimuli
Flexor withdrawal reflex arc	cutaneous receptors via Ins to flexor muscles
Flexor withdrawal reflex arc function	protective withdrawal mechanism
Crossed extension reflex stimulus and response	noxious stimuli – Flexors excited with extensor inhibition, opposite on CL side
Crossed extension reflex function	coordinates reciprocal limb activities such as gait
3 elements of Glasgow Coma Scale	eye opening, motor response, verbal response
Scoring of GCS	3-8 severe, 9-12 moderate, 13-15 minor
State defined by no eye opening even to pain, failure to obey commands, inability to speak	Coma
Return of sleep/wake cycles, normalization of basic functions, lack of cognitive responsiveness	Vegetative state
Central language DO with speech is awkward, restricted, interrupted, produced with effort	Expressive aphasia (Broca’s, nonfluent, motor)
Expressive aphasia result of	L hemisphere – Broca’s area
Impairment of volitional articulatory control 2/2 cortical dominant hemisphere lesion	Verbal apraxia
Impairment of speech production	Dysarthria
Central language DO where spontaneous speech preserved/smooth while auditory comprehension impaired	Receptive or Wernicke’s aphasa
Receptive aphasia is result of damage to	Posterior frist temporal gyrus of L hemisphere (Wernicke’s area)
Severe aphasia with impairments in comprehension & production of language	Global aphasia
Periods of apnea followed by gradually increasing depth/frequency of respirations	Cheyne Stokes respiration
Cheyne Stokes caused by	depression of frontal lobe and diencephalic dysfunction
Increased rate and depth of respirations	Hyperventilation
Hyperventilation can be caused by dysfunction of	lowere midbrain and pons
Abnormal respiration with prolonged inspiration	Apneustic breathing
Apneustic breathing is result of damage to	upper pons
Elevation of temperature may be damage to	hypothalamus or brainstem
Signs of meningeal irritation	Kernig’s sign, Brudinski’s sign, guarding in neck flexion, photophobia, disorientation, restlessness, persistent HA that increases with head down, altered vitals, weakness
Kernig’s sign	meningeal irritation. Supine with flexed hip/knee to chest then extend knee.
Brudzinski’s sign	meningeal irritation. Supine, flex neck. Causes flexion of hips/knees
Increased ICP leads to	restless, confused, decr LOC, incr BP, widening pulse P & slowed pulse, Cheyne-Stokes, elevated temp, HA, vomiting, unequal pupils, slowed PLRs, dilated pupils*, papilledema, weakness, hemiplegia, Babinski, decorticate or decerebrate rigidity, seizures
Joint position sense	test for ability to perceive joint position at rest in response to passive positioning
Kinesthesia	movement sense
Pallesthesia	vibration sense with tuning fork
Combined cortical sensation testing	discriminative sensory tests including Steriognosis, Tactile Localization, Two Point Discrimination, Bilateral Simultaneous Discrimination, Barognosis, Graphesthesia, Texture recognition
Stereognosis	ID familiar objects by touch
Two point discrimination	ability to recognize one or two blunt points applied to skin simultaneously
Barognosis	ability to differentiate weights
Graphesthesia	ability to ID numbers, letters or symbols traced on skin
Homonymous hemianopsia	loss of half of visual field in each eye contralateral to side of cerebral hemisphere lesion
Somatognosia	body scheme disorder – unable to ID body parts or relations to each other
Unilateral neglect	patient ignores one side of body and stimuli from that side
Anosognosia	severe neglect or denial of severity of condition
Figure ground discrimination	spatial relations syndrome with lack of ability to pick out object
Form constancy	pick out object from array of similar shapes but different sizes
Spatial relations	pt duplicates a pattern of 2-3 blocks
Topographical disorientation	navigation of a familiar route
Vertical disorientation	inability to accurately determine what is upright
Agnosia	inability to recognize familiar objects with one sensory modality
Apraxia	inability to perform voluntary learned movements in the absence of loss of sensation , strength, coordination, attention, or comprehension. Breakdown in conceptual or motor production system or both
Ideomotor apraxia	cannot perform task on command, but can do independently
Ideational apraxia	cannot perform the task at all, either on command or independently
Clasp-knife response	marked resistance to PROM suddenly gives way
Clonus	maintained stretch stimulus produces cyclical spasmodic contraction, usu plantar flexors or wrist flexors
Babinski	DF of great toe with fanning of other toes with stroke to lateral bottom of foot
Babinski indicates	corticospinal (pyramidal) tract disruption
Hyperreflexia	increased DTRs
Lead pipe Rigidity	uniform throughout range
Cogwheel rigidity	interrupted by series of jerks
Decerebrate posturing	increased tone in extension, seen in brainstem lesions between superior colliculus and vestibular nucleus
Decorticate posturing	UEs in flexion, LEs in extension, seen in brainstem lesions above superior colliculus
Opisthotonos	arching back of head back and heels with UEs rigidly flexed. Seen in severe meningitis, tetanus, epilepsy, strychnine poisoning
Plantar reflex	Normal is PF of toes in response to stroking lateral sole of foot from calcaneus to 5th met, S1-2, tibial nerve
Abdominal reflex	T6-L1, lateral to medial scratching of skin to umbilicus in each of 4 quadrants should cause deviation of umbilicus to stimulus
Cremasteric reflex	L1-L2, stroking of skin on inner thigh elevates testicle, lost in SCI and Corticospinal lesions
Sources of fatigue	CNS/central fatigue, neural/myoneural fatigue, muscle contractile failure
CNS/Central fatigue	in MS, ALS, CFS
Neural/myoneural junction fatigue	MS, Post Polio syndrome, GBS, myasthenia gravis
Muscle contractile failure fatigue	metabolic changes at muscle, muscular dystrophies
Extrapyramidal disorders (basal ganglia dysfunction)	Tics, Chorea, athetosis, tremors, myoclonus
Tics	spasmodic contractions of specific muscles
Chorea	relatively quick twitches or dancing movments
Athetosis	slow, irregular, twisting movements, esp in UEs
Tremor	continuous quivering mvmt, rhythmic, oscillatory observed at rest
Myoclonus	single, quick jerk
Cerebellar disorders cause	intention tremors
Cortical disorders cause	seizures, tonic/clonic convulsive mvmts
Dyssynergia	impaired ability to associate muscles together for complex mvmt
Dysmetria	impaired ability to judge distance or range of movement
Dysdiadochokinesia	impaired ability to perform rapid alternating movements