The Nervous System Part2 Flashcards
(20 cards)
Tracts
Bundle of axons in the CNS
Ascending tracts
Carry sensory info from receptors -> brain
*3 neurons
1st order neuron
2nd order neuron
3rd order neuron
*Decussation cross
From 1 side to the other side of the body in the spinal cord/brain stem
E.g Left side of the body ->right cerebral cortex
Descending tracts
Motor commands from brain to spinal cord
E.g Upper motor neuron cortex -> Lower motor neuron in brainstem/spinal cord
Decussate
Therefore control opposite side of body
Spinal nerves
Afferent fibres ofsensory nerve
Motor spinal nerves
Efferent fibres of motor neurons
Mixed spinal nerves
Afferent + efferent fibres
Most common nerve type in our body
Ganglion
Swollen part
Containssomas of peripheral neurons
Dorsal root
Carries sensory said signalsto dorsal horn
Dorsal root ganglion
Somas (cell body) of sensory neurons
Ventral root
Site that receives motor sognals from ventral horn
Spinal nerve branch to:
Dorsal ramus
Ventral ramus
Meningeal branch
Ventral rami
Give rise to network like nerve plexuses 5plexuses Cervical plexus - neck (C1-C5) Brachial plexus - shoulder (C5-T1) Lumbar plexus - lower back (L1-L4) Sacral + coccygeal plexus (S4-Co1)
Reflex
Quick + individual reaction of muscles to stimulation
Somatic reflex
Response of skeletal muscles e.g response to hot stove
Employ neural pathway -> reflex arc
Reflex arc -> somatic receptors -> afferent nerve fibre -> spinal cord/bs
Spinal cord/ Brain stem = integrating centre
Determine of efferent neuron gives a signal to muscle
Response is sent to skeletal muscle via efferent nerve fibres
Monosynaptic reflex arc
Simplest reflex arc
No interneuron between afferent + efferent neuron
E.g Patellar reflex
Polysynaptic reflex
Involves more interneurons between afferent + efferent neurons
E.g withdrawal reflex
Paralysis
Common consequence of spinal cord trauma
Paraplegia
Paralysis of both limbs from lession at (T11-L1)
Quadriplegia
Paralysis of all four limbs resulting from lesions above level C5
