MS1 Spinal Cord and Spinal Nerves Flashcards
What are the components of the CNS
brain and spinal cord
What are the components of the PNS
cranial and spinal nerves, ganglia, and associated terminals (motor endings and sensory receptors)
Where is the spinal cord found
within the vertebral column
What is the function of the spinal cord
allows communication between brain and body, conducts reflexes as part of the CNS
What is the positioning of the spinal cord within the vertebral canal
The spinal cord is shorter than the vertebral column
What causes the spinal cord to be shorter than the vertebral column
differential growth
the vertebral canal grows faster than the spinal cord
Where will the spinal cord end in adults
L1-L2
Where will the spinal cord end in infants
L3-L4
How many nerve pairs are found in each segment of the spinal cord
Cervical 8 Thoracic 12 Lumbar 5 Sacral 5 Coccygeal 1
What are the two enlargements of the spinal cord
cervical enlargement and lumbar enlargement
What is the cervical enlargement
Innervation to the upper limb C5-T1
What is the lumbar enlargment
L1 to S3, innervation to the lower leg
What is seen beyond the lumbar enlargment
spinal cord tapers to form conus medullaris
What is gray matter composed of
cell bodies of motor neurons in the spinal cord
What is white matter
axons of sensory neurons in the spinal cord
What is contained within the anterior horn of the spinal cord
Cell bodies of GSE neurons that will travel through the anterior root
What is found in the DRG
cell bodies of sensory neurons through the posterior root
What is the conus medullaris
tapered termination of spinal cord past the lumbar enlargement
Where is the conus medullaris found
L1-L2
What is the cauda equina
inferior projection from conus medullaris composed of lumbar and sacral roots to the lower limbs, buttocks, and perineum
What is the conus medularis surrounded by
CSF
Where is the conus medularis housed
lumbar cisterne
How are spinal nerves named
Cervical: based on the vertebral body number below, except for C8 (exit above vertebrae, except C8)
Thoracic and Lumbar are named for vertebral body above (exit below vertebrae)
What spinal level will be affected by a posterolateral herniation
The spinal cord level below where the herniation occurs
What spinal level will be affected by a lateral herniation
THe spinal cord level at where the herniation occurs
WHy do posterolateral herniations impact the nerve exiting below
spinal nerves hug a pedicle of the corresponding vertebrae as they exit through the intervertebral foramen
What do vertebral arteries contribute to the spinal cord
anterior and posterior spinal arteries
What do body wall arteries (from aorta) give rise to
segmental spinal arteries
What do the segmental arteries give rise to
segmental medullary arteries
anterior and posterior radicular arteries
What are segmental medullary arteries
feed spinal arteries 8-10
What are anterior and posterior radicular arteries and where are they located
every level, and supply roots
What is the artery of Adamkiewicz
segmental medullary artery, major supply of blood to lower spinal cord
Why is the artery of Adamkiewicz significant from a clinical standpoint
it comes from the left and is at risk during hernia repair and abdominal surgeries
What occurs if the artery of Adamkiewicz is damaged
leads to weakness and sensory loss in the lower limbs
What is the clinical significance of venous drainage of the spinal cord and vertebral column
valveless and allows easy spread of cancer cells
What composes the venous drainage system of the spinal cord
anterior/posterior spinal veins
internal vertebral plexus
intervertebral veins
Where is the internal vertebral plexus located
in the epidural space
What is the venous system of the vertebral columns
basivertebral veins
external vertebral plexus
Where are the basivertebral veins
in the vertebral bodies
Where are the anterior and posterior spinal veins
they go to the anterior and posterior roots of the spinal nerve
What are the meninges found on the spinal cord
dura mater
arachnoid mater
pia mater
What do the lateral extensions of the dura mater enclose
proximal portion of spinal nerve
What is the name for the dura mater that covers the proximal portion of spinal nerve
dural root sheaths
Where do the dural root sheaths go
merge with epineurium
What are the attachments of the dura mater
foramen magnum and vertebral bodies of C2-C3
inferiorly ends at S2
What type of structure does the dura mater have
dense elastic membrane
Does the dura mater receive blood supply and innervation
yes
What is the structure of the arachnoid mater
delicate fibrous and elastic membrane
What connects the dura mater to the arachnoid mater
pressed against by the pressure of CSF
Where does the arachnoid mater extend to
extends to S2
What does the arachnoid mater do at S2
lines the dural sac and dural root sheaths
Where are arachnoid trabeculae found
In the subarachnoid space
What are the meningeal spaces
subarachnoid
subdural space
epidural space
Where is the epidural space
between bone and dura
Is the epidural space a real or potential space
real
What is another name for the epidural space
extradural space
Where is the subdural space
between dura and arachnoid mater
Is the subdural space real or potential
potential
Where is the subarachnoid space
between arachnoid and pia mater
Is the subarachnoid space real or potential
real
What meningeal layer has denticulate ligaments
pia mater
What is the function// structure of denticulate ligamaments
lateral extensions that anchor spinal cord to dura mater
Describe the structure of the pia mater
thin transparent membrane that is vascular tissue
Where is the pia mater located
invests brain and spinal cord, directly covers spinal nerves
What is the filum terminale
pia mater exension that tethers the tip of the conus medullaris to the end of the sacrum
When will filum terminale be invested in dura mater
S2
What does the filum terminale become at S2
filum terminale externum
What does the filum terminale externum do
descend to coccyx anchoring the spinal cord to the dural sac
What is thethered cord syndrome
filum terminale is too short or there is something restricing its growth, sitting too low in the can, tension
What layers need to be crossed to do a lumbar puncture
skin, superficial fascia, thoracolumbar fascia, erector spinae, multifidus, rotatores, interspinous ligament, supraspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater
What are the two pops heard in a lumbar puncture
pop through ligamentum flavum and dura mater
What is the functional unit of the nervous system
neuron
What is a neuron composed of
cell body, dendrites, axon
How does a neuron receive and transmit information
receives info from other cells through dendrite
sends information to other cells through axon
What are the different types of neurons
bipolar
pseudopolar
multipolar
What are usually multipolar neurons
motor or interneurons
What are bipolar neurons
special sensory
Where are bipolar neurons typically found
retina and CN VIII
What are usually uni/pseudopolar neurons
sensory
Where are sensory neuron cell bodies usually found
in ganglia
What are collections of neuronal cell bodies called in the CNS and PNS
ganglia in PNS
gray patter in CNS
What are bundles of axons called in CNS and PNS
white matter in CNS
PNS: root, ramus, nerve
How will afferent signals move
towards CNS
What are afferent signals
sensory
How will effernt move
away from CNS
What are efferent signals
motor
What is general innervation
touch, pressure, proprioception, vibration, pain and temperature
What is somatic innervation
body wall
What is visceral innervation
smooth and cardiac muscle, glands, and erector pilli
What are GSE neurons
general somatic efferent
Where do GSE neurons go, what type of neuron, and what signal
to the body wall, motor, multipolar
Where do GSA go, what type of neuron, and what signal
from body wall, sensory, pseudounipolar
Where do GVE go, what signal and what type of innervation
to viscera, motor, autonomic innervation
Where do GVA go and what signal type
viscera, sensory
Where are the cell bodies of GSE
anterior horn of spinal cord
How do GSE fibers run to innervate body
out anterior root
go to spinal nerve
split between anterior and posterior rami
What type of info is carried in the anterior root
motor (GSE, GVE)
What type of info is carried in the posterior root
sensory (GSA, GVA)
What information is carried in a spinal nerve
motor and sensory
What information carried in the posterior and anterior rami
motor and sensory
What are the nerve plexuses discussed
lumbar and brachial
What is the organization of a nerve and their related connective tissues
endoneurium around a single axon
perineurium around fascicle
epineurium coating around whole nerve
What is a dermatome
area of skin innervated by a single spinal cord level
What provides sensation to the posterior aspect of the neck and trunk
posterior rami
What is a myotome
muscles innervated by a single spinal cord level
What is neuropathy
pathology of a peripheral nerve
What will neuropathy affect
structures the nerve innervates, not whole dermatome and myotomes
What is radiculopathy
pathology of a spinal nerve or an anterior root
What will radiculopathy affect
myotome or dermatome
the cervical enlargment of the spinal cord is due to what structure
brachial plexus
The lumbar enlargement of the spinal cord is due to what structure
lumbar plexus
What is contained within the subarachnoid space
CSF, blood vessels, and CT
where do 95% of disc herniations occur
L4-L5, or L5-S1
WHen should an epidural not be performed
if you have a fresh tattoo in that area
WHere is a lumbar puncture performed
above or below L4-L5 spinous process
Is lumbar puncture safe in newborns
yes
When should a lumbar puncture not be performed
when someone has cranial pressure as this will cause cranial herniation
What are the segmental spinal arteries that are from certebral artery
variable segmental medullary arteries
anterior radicular
posterior radicular
What plexus is a big role in metastasis of prostate cancer
basins plexus in vertebral venous system of internal venous plexus
What is varicella zoster
chicken pox or shingles
In shingles, how do we see lesions appear
along the dermatome
Why does shingles follow the dermatome
infection is inside that spinal nerve level on one side
What is a sclerotome
innervation of skeletal bones and cells
