Spinal Cord A & P Flashcards
at what level does the spinal cord end
-what accounts for this disparity in length between the spinal cord and spine
L1-L2
differential growth of the spinal cord versus the vertebral column
location of observable enlargements in size of spinal cord
-what do these enlargements indicate
cervical region
lumbar/sacral regions
marks the areas of the spinal cord that contain the neurons concerned with the upper and lower extremities
cord continues into what
- rostrally
- caudally
rostrally
-medulla
caudally
-conus medullaris
the dorsal and ventral roots of the lower lumbar and sacral segments continue caudally to exit…
-the collection of these long roots is the…
their appropriate intervetrebral foramina
cauda equina
the dura mater consists of…
meningeal layer
-periosteal layer ends at foramen magnum
epidural space is filled with…
fat
arachnoid mater actions as the limiting component of…
CSF containment
CSF gets into the subarachnoid space of the spinal canal after leaving the…
foramina of Luschka and Magendie
what is the lumbar cistern
large pocket of subarachnoid space below the caudal tip of the cord
where are spinal taps usually made
-another name for spinal tap
in lumbar cistern
aka lumbar puncture
pia components
pia intima
-adhered directly to the spinal cord
pia externa
-forms the denticulate ligaments
what are the denticulate ligaments
-purpose
extensions of the pia that protrude from the lateral sides of the cord and pierce the arachnoid to attach to the dura
help anchor and stabilize the cord in the vertebral canal
what is filum terminale
ligaments at caudal end of conus medullaris that extends to anchor the cord
filum terminale
-conposition
pia
glial elements
maybe some remnants of coccygeal neuronal elements
as the filum terminale extends through and is encased with the dura to attach to the coccyx, it is termed…
-function
coccygeal (sacral) ligament
anchors end of the cord in the spinal canal
gray matter consists of…
neuron cell bodies
glial cells
white matter consists of…
myelinated axons
white matter contains…
-these can be divided into what general locations
dorsal (posterior) funiculus
lateral funiculus
ventral (anterior) funiculus
funiculus
- general term for…
- each funiculus is composed of….
general term for an area of white matter
composed of a number of specific named tracts
the naming of each specific pathway in a funiculus can be…
descriptive of location within the transverse section of the spinal cord
may also give an indication of what areas within the CNS the pathway is connecting
important regions of the gray matter (with laminae numbering)
Lissauer’s tract (dorsolateral tract of Lissauer)
dorsal horn: substantia gelatinosa (II)
dorsal horn: nucleus proprium (III, IV)
dorsal nucleus of Clarke (VII, in part)
intermediolateral cell column or lateral horn (IX, in part)
ventral horn: location of the lower motor neurons (IX, in part)
Dorsal nucleus of Clarke segmental levels
T2-L2
intermediolateral cell column or lateral horn segmental levels
C8/T1-L2
S1-S3
dorsal horn is concerned with…
incoming sensory information
there is a _____ organization of the fibers than enter the cord via the dorsal root
medial to lateral
dorsal root
- more medially situated fibers are…..
- more laterally situated fibers are…
medial
-large diameter, heavily myelinated (Ia/b, A-alpha, II)
laterall
-small diameter, non-myelinated C fibers
dorsal root
- fibers of intermediate caliber that are finely myelinated lie…
- what ones are these
between the large and small diameter fibers
a-delta
ventral horn contains
- these are knows as
- this is the…
cell bodies with axons that will leave the spinal cord and innervate muscles
lower motor neurons
Final Common Pathway for information that is needed to make a muscle do its thing
what are the two types of lower motor neurons within the ventral horn
alpha-motor neurons
gamma-motor neurons
how are alpha and gamma motor neurons situated in the ventral horn
medially situated are concerned with axial musculature
laterally situated innervated muscles of the extremities
posteriorly situated are concerned with flexion
anteriorly situated are concerned with muscles of extension
spinal nerve formed from…
merging of the dorsal and ventral roots
associated with the spinal nerves at spinal cord levels T1-L2 is a series of…
-these are the location of…
autonomic ganglia
these ganglia are the location of the postganglionic cell bodies for the SNS
where are the preganglionic cell bodies located
lateral horn in the spinal cord
-intermediolateral cell column
what are reflexes
specific, stereotypes motor responses ta an adequate stimulus
reflexes require a series of structures consisting of at least what components
receptor
afferent limb
efferent limb
effector organ
reflexes
-receptor examples
muscle spindle
GTOs
encapsulated and free nerve endings
reflexes
-afferent limb function, example
carries the impulse (stimulus) into the CNS
i.e. dorsal root fibers
reflexes
-efferent limb function, example
carries the impulse for the response out of the CNS
i.e. lower motor neuron (alpha-motor neuron)
reflexes
-effector organ examples
skeletal muscle
glands
stretch reflex/deep tendon reflex (DTR)
- example
- demonstrates principles of…
patellar ligament example
demonstrates
-autogenic facilitation
-reciprocal inhibition
Hoffman (H-reflex)
- elicited with…
- what happens
- used to test…
elicited with a low frequency stimulation of the Ia fibers of the muscle spindle (activation without stretch)
this stimulation then results in muscle contraction of the muscle
used to test the integrity of the monosynaptic connections within the spinal cord
tendon organ reflex
- how does it occur
- demonstrates what principles
GTO stimulus
at a certain point of increased tension, the stimulus generates an inhibitory influence to the a motor neurons that are driving the contracting muscle, demonstrating the principle of autogenic inhibition
muscle can now relax
through the interneuronal pool, the antagonistic muscle can be activated to facilitate the release of tension, reciprocal facilitation
flexor withdrawal reflex and crossed extension reflex
-what occurs
reciprocal inhibition of antagonist or opposing muscle masses must occur
recurrent inhibition
-(Renshaw cells) same muscle and synergists
non-reciprocal inhibition - inhibits agonists, synergists and antagonists (coordination of various movements)
segmental loss involves…
strucutures that are present at the specific segmental level
-includes the gray matter areas of the cord and to some extent the dorsal and ventral root components that are bringing in sensory information and/or sending out motor information
segmental loss
- generally does not refer to…
- in the real world however…
does not refer to the additional involvement of ascending or descending white matter pathways
in the real world, segmental losses will most likely include some involvement of the white matter
