Spinal Cord and Somatic Nervous System Flashcards
what are all named nerves classified as?
peripheral nerves
what are sensory nerves?
AFFERENT –> towards CNS
what are motor nerves?
EFFERENT –> away from CNS
describe cranial nerves
-12 pair
-brain, brainstem
-pass through foramina in skull
describe spinal nerves
-exact number varies from species to species
-from spinal cord
-pass through intervertebral foramina
describe the somatic nervous system (motor and sensory)
-innervates the body wall (parietal structures)
-provides voluntary motor control over skeletal mm
-includes most of the cranial nerves and the spinal nerve
what is each spinal nerve complex responsible for?
one dermatome = body segment
describe the spinal nerve complex
includes both the somatic nervous system and part of the ANS
what is grey matter?
cell bodies
what is white matter and why is it white?
axons
b/c its myelinated
what is the grey matter subdivided into?
dorsal and ventral horn (each leads to dorsal and ventral root)
where are somatic cell bodies and somatic motor axons found respectively?
cell bodies –> ventral horn
motor axons –> ventral root
where are sensory cell bodies and sensory axons found respectively?
cell bodies –> dorsal root ganglion
axons –> dorsal root
what is the mixed spinal nerve and where is it found?
mixture of dorsal and ventral roots
found distal to the dorsal root ganglion
where do dorsal rami go?
epaxial musculature
where do ventral rami go?
hypaxial musculature
what is CNS gray matter?
-cell bodies of neurons and glia
-proximal dendrites, glial processes
-neuropil
what are neuropils
dense meshwork of fibers and glial cell processes
no CT integrated into CNS
what is CNS white matter?
-axons mostly myelinated
-glial cells
what is the conus medullaris?
the end of the spinal cord –> varies across mammals
vertebral column grows faster than spinal cord
SPINAL CORD ALMOST ALWAYS STOPS BEFORE THE VERTEBRAL CANAL
what is the cauda equina?
the extension of dorsal and ventral roots to the same numbered vertebral level
describe how nerves come out from vertebrae
C1-C7: cranial area/comes out above
extra C8 so T1-T2 nerves come out CAUDAL
what are the meninges?
-coverings of the spinal cord
-CTs
-support, protect
-dura mater, arachnoid mater, pia mater
what is the dura mater?
–> means tough mother
-external meningeal layer
-continuous with the true dura of the brain
-surrounded by extradural fat in the epidural space
-extends laterally onto proximal spinal nerves
=dural sheath
anchored to the caudal vertebrae via the filum terminale
what is the arachnoid mater?
=spider mother
-just deep to the dura and adherent to it
-thin and delicate
-encloses the subarachnoid space, filled with CSF
-continuous with the subarachnoid space around the brain
what is the pia mater?
=tender mother
-innermost meningeal layer
-completely adherent to the spinal cord
-create denticulate ligaments
-creates filum terminal internus
