Lect 2 Spinal Cord Flashcards
Afferent (sensory nerve) fibers
carry information from sensory receptors in skin to CNS
synapse in Posterior Horn
Efferent (motor) nerve fibers
carry information from the CNS to the periphery (eg. innervate skeletal muscles)
leave from Anterior horn
Afferent & Efferent Nerve
they are different fibers but run within the same nerve, can be thousands of axons within a nerve
spinal rootlets
thin bundles of afferent and efferent fibers/axons
spinal root
formed by groups of rootlets that converge dorsal root (sensory) ventral root (motor)
spinal nerve
formed by union of dorsal root and ventral root
spinal segment
the region between two groups of rootlets
order of spine components converging
rootlets-> spinal root -> spinal nerve -> spinal segment
Spinal cord
part of CNS
31 pairs of spinal nerves that emerge from spinal cord are part of the PNS
rostral spinal cord is continuous with brainstem
Technically ends at L1 vertebral level, but extends with vertebral bodies
Pairs of spinal nerves
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
brainstem
part of CNS
Cranial nerves III - XII emerge from brainstem and are part of PNS
conus medullaris
levels L1-L2
bony vertebral level where spinal cord ends
cauda equina
below conus medullaris
collection of nerve roots that course inferiorly to reach its corresponding intervertebral foramen
best place for a spinal tap
below the conus medullaris
filum terminale
extension of the pia mater
anchors the spinal cord caudally to coccyx
myelin stain of spinal cord
gray matter: unstained
White matter: stained
nissl stain
gray matter: stain
white matter: unstained
Spinal Cord white matter components
Dorsla Funiculus
Lateral funiculus
Ventral Funiculus
all further subdivided into fasiculi and tracts
Propriospinal fibers
confined to the spinal cord, begin and end
are predominantly located at the margins of gray matter (surround interior aspects of the funiculi)
allow for communication bw neurons at the same and distant spinal cord levels and are thought to be important in reflex circuitry
Gray matter of spinal cord
4 areas Dorsal horn intermediate zone ventral horn area around central canal
These further subdivide into laminae, demarcations of laminae are based on size and shape of neurons, their inputs and projections
dorsal horn laminae
1-4
intermediate zone laminae
7
ventral horn laminae
8-9
area around central canal laminae
10
Spinal cord segments white matter pattern
Amount of white matter decreases rostral to caudal
Grey matter of spinal cord
cervical enlargement - C5-T1
lumbar enlargement - L2-S3
location of anterior horn cell bodies- motor to upper extremities and lower extremities
cervical and lumbar enlargements
formed by increased numbers of anterior horn cells
neurons project their axons to muscles of UE & LE
T1 to L3
Lateral horn/ intermediolateral cell column is also gray matter, this is the site of preganglionic sympathetic neuronal cell bodies
lateral horn
site of preganglionic sympathetic neuronal cell bodies
