spinal nerves and membranes

spinal nerve

joining of 2 nerve roots (an anterior and a posterior combine)

ventral nerve roots

anterior

efferent - motor signals

lay deeper so they are more important

efferent

motor information, brain signals exit the brain and travel to periphery

afferent

sensory info- sends info from the periphery to the brain

dorsal nerve root

posterior

afferent- sensory info

more superficial than a ventral nerve roots

C3 and below

have both ventral and dorsal nerve roots

ventral ramus

superhighway

motor and sensory

goes to body muscle, extrinsic back, and limbs

dorsal ramus

country road - doesn’t travel far

motor and sensory

intrinsic back muscles

grey matter

composed of cell bodies

located deep= important

white matter

composed of axons- myelinated fibers carry information

surround grey matter

dorsal horn

afferent

ventral horn

efferent

epidural space

superficial to duramater

contains fat, lymphatics, and venous networking

only around the spinal cord

dura mater

outermost membrane “tough mother”

durable

subdural space

potential space- not filled with anything (like a closed ziplock bag)

becomes a space when there is an infection

arachnoid mater

middle layer

thin and delicate with spider like limbs

connects to pia mater

subarachnoid space

cerebrospinal fluid filled space between arachnoid mater and pia mater

pia mater

innermost layer, highly vascular

dentate ligaments

connect pia mater to the dural sac

provides stability and still allows mobility

conus medullaris

where the spinal cords end between T12 and L3

cauda equina

the nerve that flow free after the spinal cord ends

where do you place an epidural

below L3

what is below the conus medullaris

lumbar cistern- a fluid filled pocket in the lower spine

external terminal filum

tether that holds the spinal cord inferior

tethered cord symdrome

filum terminalis has no elasticity, so the spinal cord cannot elongate