spinal cord and spinal nerves Flashcards
exam 2
spinal cord- length and segments
extends from foramen magnum to L2, made of cervical, thoracic, lumbar, sacral
how many pairs of spinal nerves are there
31
cervical vs lumbar enlargements
cervical- supplies upper limbs
lumbar- supplies lower limbs
conus medullaris
tapered inferior end of spinal cord
cauda equina
origins of spinal nerves extending inferiorly from lumbosacral enlargement and conus medullaris
meninges
connective tissue surrounding the spinal cord and brain
dura mater
outermost, thickest membrane of spinal cord, continuous with brain dura mater
arachnoid mater
thin, whisky middle membrane of spinal cord
pia mater
innermost membrane of spinal cord, bound tightly to surface of brain, forms film terminal
filum terminale
anchors spinal cord to coccyx
denticulate ligaments
attach spinal cord to dura mater
epidural space
between bone periosteum and dura mater, contains roots of spinal nerves, blood vessels
subdural space
between the dura mater and arachnoid mater, contains a small amount of serous fluid
subarachnoid space
between arachnoid and Pia mater, helps nourish NS, contains CS fluid and blood vessels
anterior median fissure and posterior median sulcus
deep clefts separating the spinal cord into right and left halves
white vs grey matter location
white: peripherally, grey: centrally
what are the 3 columns of white matter
ventral, dorsal, lateral
what do white matter tracts do
carry info to or from the CNS
what are the 3 gray matter horns
posterior (dorsal), anterior (ventral) and lateral (ANS)
commissure
a connection btwn the right and left halves of the spinal cord
white vs gray commissures
gray: contains central canal, connects gray spinal cord.
white: connects white spinal cord
what do the spinal rootlets form
roots: dorsal and ventral
how do spinal nerves arise
as rootlets
dorsal vs ventral root
dorsal: has a ganglion, sensory/afferent
ventral: motor axon, efferent
spinal nerve
where the dorsal and ventral roots converge, called a mixed nerve bc it contains both sensory and motor axons
dorsal root ganglion
collection of cell bodies of sensory neurons from the periphery forming dorsal roots
ventral root
contains axons of motor neurons, has cell bodies located in anterior or lateral horns
lateral vs anterior gray matter horns
anterior: somatic motor neurons
lateral: autonomic motor neurons
pairs of spinal nerves per section
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
dorsal ramus of spinal nerves
innervates deep muscles of the trunk responsible for movements of the vertebral column and skin near midline of back
ventral ramus of spinal nerves
forms intercostal nerves in the thoracic region, or form 5 plexuses
5 plexuses of the spinal nerve ventral rami
- C1-C4= cervical
- C5-T1= Brachial
- L1-L4=lumbar
- L4-S4= sacral
- S5 and Co= coccygeal
cervical plexus
C1- C4, innervates superficial neck muscles, skin of neck and posterior head
brachial plexus
C5-T1, 5 ventral rami that form 3 trunks that separate to 6 branches: the axillary, radial, musculocutaneous, ulnar, median
Axillary branch of brachial plexus
innervates the deltoid, tires minor, sensory info for inferior lateral shoulder
radial branch of brachial plexus
innervates all extensor muscles of the upper limb, supinator, brachioradialis, sensory info to posterior upper limb, lateral 2/3 of dorsal hand
musculocutaneous branch of brachial plexus
innervates anterior muscles of the arm, flexor muscles, sensory info to lateral forearm
median nerve branch of brachial plexus
innervates all flexor muscles of the forearm except 1, wrist flexors, thumb muscles, sensory info to lateral 2/3 of palm
ulnar nerve branch of brachial plexus
innervates intrinsic hand muscles, sensory to medial 1/3 of hand (little finger and medial half ring finger)
lumbar and sacral plexus
lumbar = L1-L4, sacral= L4-S4. house obturator, femoral, tibial, common fibular (peroneal) nerves
obturator nerve of lumbosacral plexus
innervates thigh adductors, sensory info to medial side of thigh
tibial nerve of lumbosacral plexus
innervates posterior thigh and leg muscles, branches into others to supply plantar, no direct sensory info but branches into foot supply
femoral nerve of lumbosacral plexus
innervates hip flexors and knee extenders (iliopsoas, sartorius, quads), sensory info to anterior and lateral thigh, medial leg and foot
common fibular (peroneal) nerve of lumbosacral plexus
innervates biceps femoris, branches into other nerves
coccygeal plexus
s5- coccygeal nerve, innervates pelvic floor, sensory input to skin over coccyx and around anus
