Question | Answer |
how many spinal nerves are there | 31 Pairs; 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal |
Nerve divisions after leaving intervertebral foramen | dorsal ramus, ventral ramus, meningeal ramus |
dorsal ramus | innervates muscles and joints of region |
meningeal ramus | re-enters vertebral canal |
2 roots | dorsal and ventral |
dorsal roots | afferent fibers from peripheral receptors |
ventral roots | efferent fibers |
ventral rami split and merge these divisions form | nerves pelxuses |
nerve plexuses | plexuses gives rise to branches or peripheral nervous system, most divisions carry motor and somatosensory fibers |
plexuses parts | cervical, brachial, lumbar, sacral, coccygeal |
dermatomes | sensory input from defined areas of the skin |
characteristics of reflexes | patterned response to a stimulus, may cause muscle contraction/glandular secretion |
5 essential components of the reflex arc | receptor, sensory neuron, integration center, motor neuron, effector organ |
types of reflex arcs | monosynaptic and polysnyaptic |
monosynaptic reflex arcs | knee-jerk reflex |
polysynaptic reflex arcs | flexor or crossed extensor reflexes |
stretch reflex | muscle is stretched which activates muscle spindles, impulses are sent through afferent fibers and then synapses |
how does a a stretch reflex synapse | through alpha motor neurons and interneurons |
alpha motor neurons | stretched muscle stimulated to contract |
interneurons | exhibits reciprocal inhibition |
flexor and crossed extensor reflexes | more processing occurs, involves coordination by cerebellum and cerebral cortex |