Dr. Ghosh - Fall 2023
spinal cord divisions
cervical: 8
thoracic: 12
lumbar: 5
sacral: 5
coccygeal: 1
spinal enlargements
cervical and lumbar
where do the cervical spine nerves exit?
above the corresponding vertebrae but C8 comes below C7
where do the rest of spinal nerves exit from?
below the corresponding vertebra
growth of spinal cord @ birth
level of the third lumbar vertebra
how does the spinal cord grow through childhood?
body and spinal column grow more than the spinal cord
where does the adult spinal cord end?
at the level of the disk between L1 and L2
length of spinal nerves
progressively longer as it continues from cervical to coccygeal segments
where does the dural sheath extend?
level of S2
lumbar cistern
space between the end of the cord and the end of the dural sheath
what is located in the lumbar cistern?
ventral and dorsal roots
what do the ventral and dorsal roots make up?
cauda equina
subarachnoid space
space between pia mater and arachnoid that is filled with CSF
epidural space
between dura and bones of vertebral column
grooves of the spinal cord
posterior median sulcus, anterior median fissure, posteriolateral septum, and anteriolateral fissure
posterior median sulcus
midline grooves in posterior white column
anterior median fissure
midline grooves in anterior aspects
largest groove in spinal cord
posteriolateral septum
dorsal root enters the spinal cord
anteriolateral fissure
ventral root exits the spinal cord
conus medularis
terminal end of the spinal cord (L1-2)
cauda equina
located below the conus medularis (L3-5) and contains peripheral nerve fibers that innervate the LE
filum terminale
tapered thin filament that comes from the end of the conus medularis and runs through the cauda equina
pia mater and neuroglia
how are the ten divisions in gray matter of the spinal cord numbered?
from dorsal to ventral
lamina I
most dorsal layer of gray matter and contains small cells and receives dorsal root fibers
sends axons to contralateral spinothalamic tract
lamina II
also named substantia gelatinosa since it contains gelatinosa cells with highly branched dendrites.
receives dorsal root axon and descending fibers from reticular formation and is a modulator for pain sensation
laminae II
contains interneurons that interconnect with other dorsal horn laminae
lamina IV
cells for ascending tracts that have long dendrites that connect lamina II and III
origin of the spinothalamic tract and receives most of the dorsal root
what laminae receives dorsal roots?
I-IV
laminae V-VI
located at the base of dorsal horn and is indistinguishable in humans
cells also provide spinothalamic tracts
laminae VII
intermediate zone with the largest region of gray matter
contains the nucleus dorsalis (clarke’s column), intermediolateral cells (sympathetic preganglionic), and sacral parasympathetic preganglionic cells
lamina VIII
ventral horn and contains motor neurons and some interneurons
receives nerve fibers from descending tracts (vestibulospinal and reticulospinal) and communicates with laminae VII and IX
lamina IX
columns of motor neurons (alpha and gamma)
lamina X
located immediately around central canal and contains crossing fibers and glial cells
internal structure of spinal cord
central area: gray matter
outer: white matter
gray matter
comprised of nerve cell bodies
white matter
consists of nerve fibers or tracts
primary sensory afferents
cell bodies in the dorsal root ganglia and is located proximally to the junction of the dorsal and ventral roots
primary afferents synapses
enter spinal cord and synapse within the dorsal horn on the second order neurons or interneurons
also synapse in the ventral horn on motor neurons and contribute to the spinal reflexes such as deep tendon reflexes (knee jerk)
ventral horn composition
alpha and gamma motor neurons and interneurons
lateral, ventral horn neuron innervation
distal limb musculature associated with joint movement
medial, ventral horn neuron innervation
proximal and axial muscles associated w postural control and stability
intermediolateral cell column
region from T1-L2/3 located between the dorsal and ventral horns
intermediolateral cell column neurons
preganglionic sympathetic neurons
how is the white matter divided?
anatomically and functionally
anatomical division of white matter
the spinal cord white matter is divided into funiculi: dorsal, lateral, and ventral
funiculi composition
long ascending fibers and long descending fibers
long ascending fibers of funiculi
convey sensory information from body to the thalamus, cerebellum, and various brainstem nuclei
found in all three funiculi
long descending fibers of funiculi
originating in the cerebral cortex or brainstem and found in the lateral and ventral funiculi
how the axon fibers run in white matter? what do they form?
longitudinally and project together to from various tracts of the spinal cord
dorsal funiculis - what do these fibers carry?
conscious proprioception, kinesthesia, discriminative touch sensation, and vibration
cuneocerebellar tracts
one of the four spinocerebellar that carry unconscious proprioception from the UE
lateral funiculis
contains both sensory and motor tracts
sensory/ascending tracts of the lateral funiculis
lateral spinothalamic, spinocerebellar, spinotectal
lateral spinothalamic sensation
pain and temperature
spinocerebellar sensation
unconscious proprioception
motor/descending tracts of the lateral funiculis
lateral corticospinal and rubrospinal
lateral corticospinal function
motor control for distal limb movements
rubrospinal function
distal limb movement
tracts of the ventral funiculis
ascending: anterior spinothalamic tract
descending: ventral corticospinal and vestibulospinal tracts
anterior spinothalamic tract
carry light touch sensation
ventral corticospinal tracts
facilitate postural control and balance correction
vestibulospinal tracts
control balance