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Bundles of fibers passing information up and down the spinal cord, connecting different levels of the trunk with each other and with the brain
Central Pattern Connectors
Pools of neurons providing control of flexors and extensors that cause alternating movements of the lower limbs
Tough collagenous membrane surrounded by epidural space filled with fat and blood vessels
Layer of simple squamous epithelium lining the dura mater and loose mesh of fibers filled with CSF (creates subarachnoid space)
Epidural Space, Dura Mater, Arachnoid Mater, Subarachnoid Space, Pia Mater
5 Layers of Meninges in the Spinal Cord
Neuron cell bodies with little myelin; site of information processing (synaptic integration)
Consists of bundles of myelinated axons that carry signals up and down, to and from the brainstem
As the fibers pass up or down the brainstem and spinal cord they cross over from the left to the right side and vice versa
First Order Neurons
Detect stimulus and transmit signals to spinal cord or brainstem (in ascending tracts)
Second Order Neurons
Continues to the thalamus at the upper end of the brainstem (in ascending tracts)
Third Order Neurons
Carries the signal the rest of the way to the sensory region of the cerebral cortex (in ascending tracts)
Dorsal Column Pathway
Pathway that functions in deep touch, visceral pain, vibration, and proprioception
Pathway that functions in pain, pressure, temperature, light touch, tickle, and itch
Proprioceptive signals from limbs and trunk travel up to provide the cerebellum with feedback needed to coordinate muscle actions
Upper Motor Neuron
Originates in the cerebral cortex or brainstem and terminates on a lower motor neuron (descending tract)
Lower Motor Neuron
Axon leads the rest of the way to the muscle or other target organ (descending tract)
Descending tract from the cerebral cortex for precise, finely coordinated limb movements
Descending tract that functions as a reflex turning of the head in response to sights and sounds
Descending tract that functions in controlling limb movements important to maintain posture and balance
Descending tract that functions in postural muscle activity in response to inner ear signals
A specific area of the skin (cutaneous) that receives sensory input from a pair of spinal nerves
Stretch (Myotatic) Reflex
When a muscle is stretched, it contracts and maintains increased tonus; Knee-jerk reflex
Flexor (Withdrawal Reflex)
Quick contraction of flexor muscles resulting in the withdrawal of a limb from an injurious stimulus
Polysynaptic Reflex Arc
Pathway in which signals travel over many synapses on their way back to the muscle
Crossed Extensor Reflex
The contraction of extensor muscles in the limb opposite of the one that is withdrawn; maintains balance by extending the other leg
Ipsilateral Reflex Arc
Reflex arc in which the sensory input and the motor output are on the same sides of the spinal cord
Contralateral Reflex Arc
Reflex arc in which the input and output are on opposite sides of the spinal cord
Reflex in which the input and output occur at different levels of the spinal cord
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