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The spinal cord extends from the foreamen magnum to?
second lumbar vertebra
Function of the PNS
Relay center between the brain and spinal cord for sensory and motor information
Major reflex center
butterfly regions of gray matter on the spinal cord
What is located in the anterior, posterior, and lateral horns in white columns?
anterior gray horn--somatic motor neuron axons that provide impulses for skeletal muscles contractions
- posterior gray horn--interneurons and axons
- of incoming sensory information
lateral gray horns--contains cell bodies for autonomic motor neurons that regulate the activity of cardiac,smooth muscles, and glands.
white columns--contain sensory(ascending) and motor(descending) tracks
Compare ascending and descending spinal tracks. What type of information do they carry?
Ascending tracts- convey sensory impulses to the brain, from the spinal cord
Descending tracks--convey impulses from the brain to the (motor) spinal cord.
two bundles of sensory and motor axons that connect to form a spinal nerve. compose of:
anterior root, posterior roots and posterior ganglion root
What is in the dorsal/posterior roots of the spinal cord?
conduct nerve impulses from sensory receptors in the skin, muscles, and internal organs into CNS
What is in the anterior/ventral roots of the spinal cord?
contain axons of motor neurons, which conduct nerve impulses from the CNS to effectors (muscles and glands)
what do the dorsal/posterior and ventral/anterior roots merge to form?
a spinal nerve
What are dorsal root Ganglia and what do they contain
swelling on the posterior (dorsal) root. ganglions, contain cell bodies of sensory neurons
What is the difference between tracts and nerves?
fiber tracts are bundles of mylelinated axons in the CNS, that transmit sensory impulses into the dorsal/posterior root nerve.
Whereas nerves are bundles of axons that transmit motor impulses out of the anterior/ventral root nerve in the PNS
What are columns?
Organized regions of myelinated white matter on the left and right sides of the spinal cord. (surrounds the gray horns)
connecting left and right regions points of gray matter in the center of the spinal cord that is shaped like a butterfly
anterior/ventral white commissure
connects the white matter of both sides of the spinal cord
anterior median fissure
a wide groove that separates the two sides of white matter on the spinal cord
posterior median sulcus
a narrow groove on the posterior side of the spinal cord that separates the white matter
located in the center of the butterfly (gray matter) that is a passage for csf
Anterior- voluntary cell bodies of somatic motor for skeletal movement
lateral--involuntary autonomic motor neurons for heart,smooth muscles, and glands
posterior--interneurons for the senses