intro to peripheral nervous system Flashcards
what is pns ?
it is made up of nerves which link the CNS to the body and are classified according to the direction which they transmit impulses as sensory, motor or mixed nerves
pns is split into what divisions?
sensory and motor
what is motor pns split into?
visceral (smooth muscles)
somatic (skeletal muscles)
what is visceral motor division split into?
parasympathetic and sympathetic
where does cranial nerve extend from?
from the brain
where does the spinal nerves extend from?
from the spinal cord
what is the structure of the nerves in pns ?
the nerves are bundled into a fascicle and then many fascicle are bound together to form a spinal nerve
what are the coverings of nerve in pns ?
- endoneurium
- perineurium
- epineurium
what does the endoneurium surrounds?
each axon is surrounded by a loose connective tissue that encloses the Schwann cells
what does the perineurium surrounds ?
it binds a group of axons into bundles called fascicles
what does the epineurium enclose?
it encloses all the fascicles to form the nerve
what emerges with the epineurium?
dura mater emerges with the epineurium
where does blood vessels lie in the nerve ?
it nourishes the nerves and lie within perineurium and epineurium
what are the different type of nerves ?
- mixed nerves
2, sensory afferent nerves - motor efferent nerves
(most nerves are mixed and they often carry both somatic and autonomic)
