Unit 4 Flashcards
how long is the spinal cord?
40-45cm long
16-18 inches
what is the maximum diameter and where?
1.3 cm maximum diameter in the cervical enlargement
where is the narrowest vertebral canal?
C5-C6 the cord occupies 75% of the vertebral canal
what is the weight of the spinal cord?
27 to 35 grams (approx 1oz)
only 2% of the total CNS weight
what is the convenient superior boundary of the spinal cord?
Foramen Magnum- line of demarcation
what is the precise superior boundary of the spinal cord?
the superior most ventral rootlet of the first cervical spinal nerve
what is the adult Inferior Boundary?
Conus Medullaris
the disc between vertebral levels L1-2
this leaves about 1/3 of the vertebral and sacral canal below
how many spinal nerve pairs are there?
31 pairs
each nerve will have what type of rootlets?
dorsal and ventral roots
what is the law that states that dorsal roots contain sensory (afferent) fibers and Ventral roots are motor (efferent) fibers?
the Bell-Magendi law
we now know a few afferent fibers come through the ventral root but the general idea is valid
Roots (rootlets), spinal nerves and their Rami are what type of structures?
PNS structures
the only CNS structure in the vertebral canal is the?
spinal cord
how are the Cranial nerves named?
they are named for the bone below
which nerve exits between the occiput and atlas?
C1 its occasionally missing dorsal rootlets
which spinal nerve exits at the intervertebral foramen between C3 and C4 vertebrae?
C4 spinal nerve
Which spinal nerve exits at the intervertebral foramen between C7 and T1 vertebrae?
C8 spinal nerve
how are the thoracic nerves named?
named for the bone above
which nerve exits at the intervertebral foramen between T1 and T2 vertebrae?
T1 spinal nerve
which nerve exits at the intervertebral foramen between T6 and T7 vertebrae?
T6 spinal nerve
which spinal nerve exits at the intervertebral foramen of the T12 and L1 vertebrae?
T12 spinal nerve
how are the lumbar nerves named?
named for the bone above
where does L1 exit from the spinal column?
L1 exits at the intervertebral foramen between
which nerve exits between L5 and S1 vertebrae?
L5
which nerve exits from the Sacral Hiatus?
the Coccygeal nerve 1
Co1, this nerve might be missing
the cord of the vertebral column are approximately the same length during the first ______ months of embryonic development.
the first three months
During the rest of gestation the vertebral column lengthens _________ than the cord.
Faster
At birth the Co1 cord level is typically at the same level as the ________ vertebra?
L2-L3
By adulthood, the Co1 cord level is found at the ______ vertebral level in about 90% of people?
L1-L2
The tapering end of the cord is called the?
Conus Medullaris
the formation of the lumbar, sacral, and coocygeal roots that is below the cord and passes through the lumbar cistern is called?
Cauda Equina
the tiny and insignificant channel near the center of the spinal cord?
central canal
cranially, the central canal is continuous with what two structures?
medulla oblongata and the fourth ventricle
inferiorly the central canal expands into the conus medullaris as a?
terminal ventricle
terminal ventricle vs. Lumbar cistern
ventricle is a passage
cistern is a resevoir
gray and white matter are found at what cord levels?
all cord levels
there are variations in relative amounts of gray and white matter through the cord levels. as you go down the cord there is less __________ matter.
less white matter
what horn is responsible for sensory afferent input which is heavy in nociceptors and thermoreceptors?
dorsal horn
which horn is primarily involved with activity in the sympathetic division of the autonomic motor system?
lateral horns
which horn control motor functions and is motor control for the axial muscles?
ventral horns
A ___________ is a longitudinal bundle of white matter fibers can be anatomically observed.
Funiculus
gray matter has a ________ concentration of neuron cell bodies.
dense
thick dendritic mats are located near the neuron cell bodies of which type of matter?
gray matter
which matter has dense capillary beds and support glial cells?
gray matter
groups of cell bodies form what?
Nuclei
how many rexed laminas are there?
10
there are many classification systems for cord nuclei based on what main 4 things?
shape
size
location of cell body
named after discoverer
which lamina is the thin cap over the posterior horn?
lamina 1
which lamina is responsible for pain and temperature sensations and gives rise to axons of the spinothalmic tract, also known as the posterior marginal nucleus?
lamina 1
which lamina appears gelatinous when examined in the fresh state?
lamina 2
which lamina has afferent fibers from lissauer’s fasiculus and carries impulse important in transmission of pain, touch, and temperature. this also known as Substantia Gelatinosa?
lamina 2
the laminas that have much of their area filled with a group of cell bodies called the Nucleus Proprius?
lamina 3 and 4
which laminas receive touch and pressure stimuli, the dendrites of some of the neurons here extend into adjacent lamina
lamina 3 and 4
which laminae have axons of certain neurons located here cross to opposite side and contribute to the spinothalmic tract?
lamina 3 and 4
on the lateral edge of this lamina is a complex of fibers and cell bodies known as?
formatio reticularis
although lamina 5 is found at all cord levels, please remember that this ___________ __________ is only at the cervical area.
reticular formation
this lamina sends axons contralaterally to the lateral spinothalmic tract?
lamina 5
the ascending tract present through the entire cord and enters the cord at T6 and below, directly into the posterior funiculus?
Gracilis
the ascending tract that is located in the medial aspect of the posterior funiculus?
Gracilis
the ascending tract that is located in the lateral aspect of the posterior funiculus?
cuneatus
the ascending tract that enters the cord at level T6 and above, enters directly into the posterior funiculus?
cuneatus
the slender tract?
gracilis
the wedge shaped spinal tract?
cuneatus
the two spinal tracts located in the posterior columns?
gracilis
cuneatus
the first neuron fibers of the gracilis terminate and synapse where?
nucleus gracilis of the medulla oblongata
the first neuron fibers of the cuneatus terminate and synapse where?
nucleus cuneatus in the medulla oblongata
the function of what tracts is to discriminate between two point touch and vibratory sensations?
gracilis
cuneatus
what are the two major carriers for kinesthetic sensation (conscious proprioception)?
gracilis
cuneatus
where do the gracilis and cuneatus fibers cross over?
internal arcuate fibers of the medulla oblongata
what would be a symptoms of a lesion of the posterior funiculus?
loss of proprioception
what is the cross over classification of the gracilis and cuneatus?
ipsilateral