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Chapter 13 Spinal Cord
bundles of fibers passing information up and down spinal cord, connecting different levels of the trunk with each other and with the brain
walking involves repetitive coordinated actions of several muscle groups.
involuntary stereotyped responses to stimuli. withdrawl of hand from pain
sylinder of nervous tissue that arises from the brainstem at the foramen magnum of the skull
part of the spinal cord supplied by each pair of spinal nerves
nerves to upper limb
nerves to pelvic region and lower limbs
medullary cone (conus medullaris)
cord tapers to a point inferior to lumbar enlargement
bundle of nerve roots that occupy the vertebral canal from L2 to S5
three fibrous connective tissue membranes that enclose the brain and spinal cord.
formes loose fitting sleeve around spinal cord - dural sheath.
layer of simple squamous epithelium lining dura mater and a loose mesh of collagen and elastic fibers spanning the gap between the arachnoid membrane and the pia mater.
gap between arachnoid membrane and pia mater.
subarachnoid space inferior to medullary cone that contains cauda equina and CSF
delicate, translucent membrane that follows the contours of the spinal cord
fibrous strand of pia mater that extends beyond the medullary cone within the lumbar cistern
formed from fusion of terminal filum and dura mater. anchors the cord and meninges to vertebra Co1
extend through the arachnoid to the dura. anchors spinal cord to limit side to side movement
congenital defect in which one or more vertebrae fail to form a complete vertebral arch for enclosure of the spinal cord.
neuron cell bodies with little myelin. site of information processing
abundantly myelinated axons. carry signals from one part of the CNS to another.
visible from T2 through L1. contains neurons of sympathetic nervous system
three pair of these white matter bundles
subdivisions of each column
carry sensory information up the spinal cord
carry motor information down the spinal cord
as the fibers pass up or down the brainstem and spinal cord they cross over from the left to the right and vise versa.
when the origin and destination of a tract are on the same side of the body. does not decussate
first order neuron
detect stimulus and transmit signal to spinal cord or brainstem
second order neuron
continues to the thalamus at the upper end of the brainstem
third order neuron
carries the signal the rest of the way to the sensory region of the cerebral cortex
carries signals from the midthoracic and lower parts of the body
nonvisual sense of the position and movements of the body
joins the gracile fasciculus at the T6 level.
formed from the second order neurons of gracile and cuneate sustems that decussate in the medulla
one fo the smaller tracts of the anterolateral system. passes up the anterior and lateral columns of the spinal cord. carrys signals for pain, pressure, temp, light touch, tickle, and itch.
ridges on anterior surface of the medulla oblongata formed from fibers of this system.
begins in midbrain region (tectum). reflex turning of head in response to sights and sounds.
amyotrophic lateral sclerosis
destruction of motor neurons and muscular atrophy.
cordlike organ composed of numerous nerve fibers (axons) bound together by connective tissue.
nerve fibers gathered in bundles
bundles numerous fascicles that constitutes whole nerve
cluster of neurosomas outside the CNS enveloped in an endoneurium continuous with that of the nerve
consists of both afferent and efferent fibers and thus conducts signals in two directions.
innervates the anterior and lateral skin and muscles of the trunk
innervates the muscles and joints in that region of the spine and the skin of the back.
reenters the vertebral canal and innervates the meninges vertebrae and spinal ligaments
carry sensory signals from bones, joints muscles and the skin
primarily to stimulate muscle contraction
radial nerve injury
passes through axilla. crutch paralysis. wrist drop.
sharp pain that travels from gluteal region along the posterior side of the thigh and leg to ankle
common disease of early childhood. caused by caricella zoster virus
localized disease caused by the virus traveling down the sensory nerves by fast axonal trasport when immune system is compromised.
a specific area of the skin that receives sensory input from a pair of spinal nerves
a diagram of the cutaneous regions innervated by each spinal nerve
stretch receptors embedded in skeletal system
specialezed sense organs to monitor the position and movement of the body parts
muscle fibers within spindle
stretch (myotatic) reflex
when a muscle is stretched, it fights back and contracts which maintains increased tonus making it stiffer than unstretched muscle.
reflexive contraction of a muscle when its tendon is tapped. ex. knee jerk.
reflex phenomenon that prevents muscles from working against each other by inhibiting the antagonist.
the quick contraction of flexor muscles resulting in the withdrawl 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 extension reflex
the contraction of extensor muscles in the limb opposite of the one that is withdrawn
ipsilateral reflex arc
one in which the sensory input and the motor output are on the same sides of the spinal cord
contralateral reflex arc
one in which the input and output are on the opposite sides
one in which the input and output occur at different levels (segments) of the spinal cord
proprioceptors in a tendon near its junction with a muscle
complete severance of cord