This site is 100% ad supported. Please add an exception to adblock for this site.

Ch 13 Gross Anatomy of the Spinal Cord


undefined, object
copy deck
groups of cell bodies in the gray matter of the CNS
posterior gray horns
contain somatic and visceral sensory mnuclei
anterior gray horns
contain somatic motor nuclei
latral gray horns
only located in the thoracic and lumbar segments contain visceral motor nuclei
gray commissure
posterior to and anterior tot he central canal containing axons that cross from one side of the cord to the other befor they reach a destination in the gray matter
white matter of the spinal cord
superficial contains large #s of myelinated and unmyelinated axons- divided into 3 regions called colums
posterior white columns
lie b/t the posterior gray horns and the posterior median sulcus
anterior white columns
lie b/t the anterior gray horns and the anterior median fissure- interconnected by anterior white commissure
lateral white column
the withe matter b/t the anterior and posterior columns on each side
contained by each column of white matter- a bundle of axons in the CNS that relatively uniform with respect to diameter, myelination, and conduction speed- all axons w/in a tract relay same kind of info in the same direction- short tracts carry info b/t segments of the spinal cord- long tracts connect the spinal cord w/ the brain
ascendind tract
carry sensory info toward the brain
preganglionic fibers
distally, the first branc from the spinal nerve that carries visceral motor fibers to a sympathetic ganglion- preganglionic fibers are myelinated- called the white ramus
postganionic fibers
innervate smoth smucles, glands, and organs in the thoracic cavity extend directly from the ganglion to their respective effector organs- form a series of sympathetic nerves- unmyelinated and gray- known as the gray ramus
peripheral neuropathies
regional losses of sensory and motor function most often resulting from nerve trauma or compression
nerve plexus
where the ventral rami of adjacent spinal nerves blend their fibers and produce a serios of compound nerve trunks; the ventral rami form 4 major pluxuses: cervical, brachial, lumbar, sacral
cervical plexus
consists of the ventral rami of spinal nervs C1-C5; the branches of the cerv plex innervate the muscles of the neck and extend into the thoracic cavity
phrenic nerve
major nerve of the cervical plexus- provides nerve supply to the diaphragm
brachial plexus
innervates the pctoral girdle and upper limb- C5-T1- nerves that form this plexus orig from trunks and cords- musculocutaneous nerve, median nerve, ulnar nerve, axillary nerve, radial nerve
large bundles of axons contributed by several spinal nerves (brachial plexus)
smaller branches that originate at the trunks (brachial plexus)
cords and trunks named after_____
their location relative to the axillary artery
Lumbar Plexus
contains axons from ventral rami of spinal nervs T12-L14
neuronal pools
functional groups of inrerconnected neurons; can be diffuse, or localized;; diff neural circuits
neural circuits
the pattern of interaction among neurons that provides clues tot the functional characteristics ofa neuronal pool: divergence, convergence, serial processing, paralellel prcessing, reverberation
rapid, automatic responses to specific stimuli- preserve homeostatsis by making rapid adjustments in the function of organs or organ systems
reflex arc
the wiring of a single reflex
steps in a simple neural stretch reflex
1. arrival of stimulus and activation of receptor 2. The activation of a sensory neuron 3. Information processing 4. Activation of a motor neuron 5. response of a peripheral effector
Reflexes are classified on the basis of:
1. Thier development 2. The nature of the resulting motor response 3. the complexity of the neural circuit involved 4. the site of info processing
innate reflexes
result from conncetions that form b/t neurons during development-appear in a predictable sequence; genetically or developmentally programmed
innate reflex examples
w/draw from pain; chewing, suckling, tracking objects w/ eyes
acquired reflexes
more complex, learned motor patterns; rapid automatic responses but are learned
Somatic Reflexes
provide a mechanism for the involuntary control of the musc. system
somatic reflex examples
superficial reflexes (those triggered by stimuli at the skin or mucous membranes; stretch reflexes (triggered by the sudden elongation of a tendon; deep tendon flex
monosynaptic reflex
simplest reflex arc; sensory neuron synapses directly on a motor neuron
polysynaptic reflex
longer delay b/t stimulus and response; can produce more complicated responses b/c the interneurons can control motor neurons that activate several muscle groups simultaneously
intersegmental reflex arcs
the most complicated spinal reflexes in which many segments interact to produce a coordinated, highly variable response

Deck Info