neuroanatomy pns 2013
DESCRIPTION
1TRANSCRIPT
THE SPINAL CORD
The spinal cord attaches to the spinal nerves that
innervate the neck, limbs, and trunk.
It also acts as a reflex center and contains axon
tracts running to and from the brain.
It extends from the foramen magnum to the level
of the first or second lumbar vertebra.
The terminal end of the spinal cord is the conus
medullaris.
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THE SPINAL CORD
Thirty-one pairs of spinal nerve roots issue from
the spinal cord.
The most inferior bundle of roots resembles a
horse’s tail (cauda equina).
The spinal cord is enlarged in its cervical and
lumbar regions, reflecting the innervation of the
limbs.
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THE SPINAL CORD
The white matter of the cord is divided into
dorsal, lateral, and ventral funiculi containing
ascending and descending fibers.
The H-shaped gray matter of the spinal cord has
two ventral horns containing motor neurons and
two dorsal horns containing interneurons.
The dorsal horns are subdivided into somatic and
visceral sensory regions; the ventral horns, into
visceral and somatic motor regions.
The roots of the spinal nerves—dorsal sensory
roots and ventral motor roots—are PNS
structures that attach to the spinal cord. 6
THE SPINAL CORD (PROTECTION OF
THE SPINAL CORD)
Three connective-tissue membranes, the
meninges, enclose and protect both the brain and
the spinal cord: the tough outer duramater, the
arachnoid, and the inner vascularized pia mater.
Cerebrospinal fluid both floats and cushions the
structures of the CNS.
It fills the subarachnoid space and the central
cavities of the brain and spinal cord.
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THE PERIPHERAL NERVOUS
SYSTEM
PNS consists of:
12 pairs of cranial nerves
31 pairs of spinal nerves
Otonomic nervous system: sympathetic and
parasympathetic.
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