Nervous Tissue Flashcards
peripheral nerve
-where are its axons located?
axons with cell bodies that are located
-within dorsal root ganglia at each spinal nerve segment
axons of motor neuron cell bodies located within ventral horn of spinal cord
sensory nerves
- other name
- function
afferent nerves
carry signals from receptors located throughout the body in the skin, muscles, connective tissue and visceral organs
motor nerves
- other name
- function
efferent
innervate all muscle tissue, voluntary striated, cardiac striated, and smooth muscle
each peripheral nerve we identify contains…
-called a…
contains both sensory and motor axons
called a mixed nerve
where is the only place the sensory and motor axons of the peripheral nerves are separated?
central to (before) the formation of the spinal nerve -the dorsal and ventral roots
dorsal root
-contains
ventral root
-contains
dorsal: only sensory axons
ventral: only motor axons
the formation of the spinal nerve occurs near or within which structure
intervertebral foramen
distal to the formation of the spinal nerve, all identified nerve bundles are considered…
mixed nerves
all peripheral nerves are encased in…
a series of CT coverings
all nerve (CT) coverings consists of… (4)
mesoneurium
epineurium
perineurium
endoneurium
each of these layers is made up of CT with… (2)
its own innervation (nervi nervosum)
its own vascular supply (vasa nervosum)
mesoneurium
- alternate name
- function
name
-paraneurium (not to be confused with PERIneurium)
function
-covering of entire nerve that allows the nerve to move independently without being impinged or constricted by surrounding structures
constriction of a nerve can result in…
irritation of the nerve
- causes it to fire abnormally
- OR
- restrict the axons from propogating their respective action potentials
mesoneurium
-CT type
loose irregular CT
epineurium
-encapsulates…
encapsulates entire nerve
more intimately attached to CT compartments of the nerve itself
can be seen encasing larger groups of axons called fascicles
perineurium
-function
further subdivides nerve to smaller fascicles that begin to correspond closely to divisions heading toward specific muscles or dermatomes
endoneurium
-most closely associated with…
individual axons
functions of CT compartments of the axons of a peripheral nerve
allow for exchange of ions for actions potentials
allow for the exchange of nutrients and metabolites for the region of the nerve
what aspects of the peripheral nerve give it the ability to “stretch” to accommodate movement around joints or areas of possible restriction
elastic property of the CT
slightly undulating arrangement of individual axons
result of temporary compression of a peripheral nerve
-common names for this phemonemon
depletion of the vascular supply to the individual axons
-results in a loss of the ability to propagate action potentials
names
-foot or hand “falling asleep”
result of prolonged compression of a peripheral nerve
longer lasting effect on the nerve similar to that of temporary compression
what is the theory of adverse neural tension
includes the idea the the peripheral nervous system (PNS) is continuous with the central nervous system (CNS)
-with respect to both neural elements and CT elements
meninges
-composition
CT
outermost layer of the CNS
- name
- continuous with what part of the PNS?
dura mater
continuous within the intervertebral foramen with the epineurium
