BS Flashcards
Babinski sign
- Upturning toes indicates pathological upper motor neuron lesion
- Corticospinal tract
Corticospinal tract
- Voluntary mvmt of body
- 80% Cross over at medulla
- Originate in cerebral cortex
- Form pyramids of medulla
- Upper motor neurons
- Synapse with interneurons
Deep tendon reflexes
- Stretch reflex, direct response from spinal cord
-Hyporeflexia- Lower motor neuron
Hyperreflexia- Upper motor neuron, pyramidal tract
Flaccid paresis
- Lower motor neuron
- Weakness, hypotonia, hyporeflexia
- GBS, encephalopathy, botulism
- Inability to contract muscles
Hemiparesis
- Injury above medulla cause contralateral hemiparesis
- Injury below medulla cause ipsilateral hemiparesis
Hyperreflexia
- Upper motor neuron involvement
- Can be DTRs or superficial
Superficial reflex
- Sensory signal must ascend to brain
- Interruption of pathway between brain and spinal cord
Hypertonia
- Upper motor lesion
- Anterior horn of spinal cord
- Reticulospinal tract
Hyporeflexia
- Lower motor neuron issue
Hypotonia
- Diminished resistance to passive movement
- Lower motor neuron disease
Internal capsule
- Ascending and descending motor neurons
- Corticospinal tract travels through
- Going to and coming from cerebral cortex
- Primary motor cotrex- hemiparesis and hemiplegia
Lateral corticospinal tract
- Fine mvmt of ipsilateral limbs
- Largest part of corticospinal tract
- Descending motor neuron
- Decussates in pyramid of medulla
Pyramidal tract
- Originate in cerebral cortex
- Carry motor fibers to brainstem, spinal cord
- Voluntary control of musculature
Extrapyramidal tract
- Originate in brainstem
- Motor fibers to spinal cord
- Involuntary control of musculature
- Tone, balance, posture and locomotion
Primary motor cortex
- Organized somatotopically
- Dorsal potion of frontal lobe
- Excites lower motor neuron, inhibits reflexes, tone
- Betz cells
- Anterior to central sulcus
- Activates contralateral side of body
- Posterior limb of internal capsule
- Cross over at medulla
Premotor cortex
- Frontal lobe, anterior to primary motor cortex
- Timed individual mvmts via direct and indirect stimulation
- Excites groups of neurons
- Spatial and sensory guidance of tasks
- Visually cued conditional tasks
- Projects to spinal cord
- Trunk muscles
Reticular formation
- Brainstem
- Interconnected nuclei, motor integration
- Behavioral arousal and consciousness
- CV control
- Pain modulation
- Habituation
- Sleep and consciousness
- Raphe, red and parvocellular nuclei
Ventral corticospinal tract
- Descending
- Cerebral cortex to spinal cord
- Ends in mid thoracic region
- Cross at anterior white commissure
- Voluntary motor impulses to precentral gyrus
Ventral horn of spinal cord
- Motor neurons of axial muscles
- Corticospinal tract runs through
- Intact sensation but weakness with lesion
Vestibular nuclei
- Medulla
- Input from CN VIII
- Lateral and medial nucleus to cerebellum
- Vestibulospinal tract- coordinate head and trunk movements
Vestibulospinal tract
- Extrapyramidal system
- Motor commands
- Alter muscle tone, extend and change position of limbs and head
- Maintain posture and balance
- Medial pathway, anterior horn cells
- Funiculus
- Righting reflex
Lateral tracts
Precise movement of distal limbs
Medial tracts
Gross movement of proximal limbs and trunk
Muscle tone
- Continuous, passive contraction of muscles
- Hypertonia = UMN
- Hypotonia = LMN
Neuromuscular junction
- Very large synapse, contact points
- LMN to skeletal musc
Nicotinic acetylcholine receptor blockers
- Paralysis of muscle, can’t sense ach
- Inhibit effect of acetylcholine
- Immobilization of pts
Acetylcholine agonists
- Nicotine is mild agonist
- Activation of cholinergic system- BP, addiction
- Stimulates muscle and doesn’t allow reexcition- exhaustion of muscle
Acetylcholinesterase blockers
- Build up of acetylcholinesterase at neuromusc jxn
- Tx myasthenia gravis
- Indirectly provided cholinergic action
- Prolongation of muscle activity
Stretch reflex arc
- Activated by DTRs
- Direct activation of LMN
- Stretch -> afferent signal -> spinal cord -> efferent reflex -> activate musc, inhibit antagonist
- Protective measure
- Responsible for muscle tone
Lateral funiculus motor systems
- Contralateral corticospinal and spinothalamic tracts
- Ventral horn
- Activate lateral musculature (forearms)
- Internal capsule
- Inhibition from ventral horn
Primary motor cortex
- Precentral sulcus of central lobe
- Analogus to primary somatosensory cortex
- Fine motor control areas larger
Corticospinal tract
- Limbs, head and trunk
Corticobulbar tract
Face, neck, throat
Lesion of lateral corticospinal tract
- Ipsilateral deficit, weakness
- Loss of fine motor movement in distal extremities
- Hypertonia/ spasticity and clonus
- Exaggerated babinski sign
Unilateral destruction at dorsal column- C4
Ipsilateral proprioception loss
Proprioception sensation
- DCML
- Decussates at caudal medulla
Unilateral destruction at dorsal root ganglion- C4
- Ipsilateral proprioceptive sensation loss
Unilateral destruction at anterolateral system- C4
- Unaffected
Unilateral destruction at lateral primary sensory cortex
Contralateral proprioception
- Loss of face
Unilateral destruction at medical somatosensory cortex
Contralateral proprioception
- Loss of limbs
Reticular activating system
- Within reticular formation
- Interconnected nuclei
- Regulates activity in cerebral cortex
- Auditory and temperature activation
- Avoidance of pain, smells
Paresthesia
- Odd, unnatural sensation
- Peripheral neuropathy,
- Damage to relay nucleus, nerve or primary cortex
Dysthesias
Unpleasant or painful sensations produced by stimulus
