EOS neuro Flashcards
Cerebral cortex impulses are modified by what?
Basal ganglia
Thalamus
Brain stem nuclei
Cerebellum
What are UMNs and what are their 3 functions?
Nerves that participate in initiation and regulation of voluntary movement.
- Initiation of voluntary activity of motor system.
- Maintenance of muscle tone in postural muscles.
- Control of muscular activity in viscera.
What are LMNs and what is their function?
Nerves that connect CNS with periphery (muscles, effector organs, glands).
Dendrites and cell bodies in grey matter, axons in white.
1. Final pathway for all motor activity of nervous system.
What are spinal reflexes?
Activity of LMNs modified by sensory info from muscles, joints and skin.
Stages of patellar reflex
- Hammer taps tendon - stretches sensory receptors in extensor muscles.
- Sensory neuron synapses with motor neuron in SC, also synapses with inter neuron which inhibits motor neuron to flexors.
- Motor neuron conducts AP to extensor muscle causing contraction, flexor muscles stay relaxed due to inhibition.
- Leg extends.
What are the stages of the cross extensor and withdrawal reflex?
- Stimulation of nociceptor.
- AP in afferent neuron.
- Stimulation of inter neurons - ipsilateral limb flexors contract, extensors relax (withdrawal). Contralateral limb extensors contract, flexors relax (extension).
What are the functions of the cerebellum?
Modifies ongoing posture and movement - motor centre activity (decreases performance errors).
Modulate motor activity - compares intention with performance (proprioceptive feedback).
Maintains posture and muscle tone.
Regulates activity of UMNs.
Learns new movements and initiates movements.
Describe the cerebellum afferent pathways?
From cerebral cortex, brain stem (vestibular nuclei) and spinal cord.
Input fibres include mossy fibres(vestibular nuclei and nerves, spinocerebellar tracts and cerebral cortex), climbing fibres (contralateral Olivary nucleus).
Travel to cerebellum nuclei and cortex - excite purkinje neurons.
Excitatory
Describe the cerebellums efferent pathways.
From purkinje neurons (vestibulocerebellum), synapse on neurons in BS motor centres and thalamic nuclei.
Project to cerebral cortex motor areas and brain stem.
Inhibitory to rest of brain.
No direct connection to LMNs - output to all major UMNs.
What is the function of the corticobulbar tracts?
Corticopontine - cortical regulation of cerebellar motor activity - fine motor activity.
Corticonuclear - regulate cranial nerve motor activity.
What are the functions of the corticospinal tracts?
Regulate postural changes required for intentional motor activity.
What are the functions of the rubrospinal tract?
Voluntary movement of flexors in fore and hind limbs - coordinates quadrupedal movement.
What is the function of the vestibulo spinal tract?
Controls balance, posture, position, movement and rotation of head.
Adjusts body in response to signals from semicircular canals,
Vestibulo ocular reflex.
What are the functions of the reticulospinal reflex?
Maintains postural tone.
Initiates feed forward adjustments.
What are the functions of the tectospinal tracts?
Coordination of head and eye movement.
What is sensory coding?
Moderation of excitation of sensory neurons to prevent sensory overload in somatosensory cortex.
How is sensory coding carried out?
Modality - receptor type
Location - receptive field, lateral inhibition
Intensity - firing rate, recruitment
Duration - adaptation (tonic receptors fire for duration of stimulus, phasic receptors firing rate decreases over time).
What is the function of the ventral spinocerebellar tract?
Somatosensation from hind limbs and body
Joints, tendons and ligaments.
What is the function of the rostral spinocerebellar tract?
Somatosensation from forelimbs and body.
Joints, tendons, ligaments.
What is the function of the dorsal spinocerebellar tract?
Somatosensation of hind limbs and body.
Muscle spindle.
What is the function of the cuneocerebellar tract?
Somatosensation from forelimbs and body.
Muscle spindle.
What information does the dorsal column medial lemniscal pathway provide?
Precise information about touch, pressure, vibration and intensity.
What are some problems associated with ascending signal transduction?
Projected pain - mechanical activation of secondary neurons from pressure on SC
Phantom limb pain - somatosensory cortex activates in absence of afferent inputs.
Referred pain - visceral and somatosensory neurons converge on same secondary neuron.
What are the possible causes of neurological clinical signs?
M - malformation I - injury I - inflammation N - neoplasia D - degeneration
