Spinal Cord and Spinal Nerves Flashcards
the spinal cord is a two way or one way conduction system?
two way
what is the spinal cord?
flattened tubular structure located within the vertebral canal and extends from medulla oblongata to approximately L1
where does the spinal cord extend in newborns?
it extends to L4 in newborn and the vertebral column grows faster than the spinal cord
what is the significance of the cervical and lumbar enlargements?
they provide peripheral nerves for extremities like the arm, forearm, thigh and leg
what are the two structures you can find at the terminal end of the spinal cord?
conus medullaris and the film terminale
what is the conus medullaris?
tapering end of spinal cord
what is the filum terminale?
tissue (actually pia mater) than extends inferiorly to anchor spinal cord to coccyx, part of covering for spinal cord
what are the meninges?
connective tissue coverings that surround brain and spinal
what are the layers of the meninges?
dura mater
arachnoid mater
pia mater
what is the dura mater?
the fibrous outer layer
what is the arachnoid mater?
middle later
what is the pia mater?
thin transparent layer that adheres to brain and spinal cord
where do we find the epidural space?
between dura and vertebral canal
where can we find the subarachnoid space?
formed by deep spider-like extensions of arachnoid»_space; contains cerebral spinal fluid»_space; protective layer around brain and spinal cord
what does the arachnoid space push against?
its pushed tight against the dura mater
what is the pia mater?
thin transparent layer that adheres to brain and spinal cord
what is an important structure we can find within the pia mater?
denticulate ligaments
what is the denticulate ligaments?
small-toothed, triangular extensions of pia that attach to arachnoid/dura mater»_space; suspend spinal cord in center of meningeal sac
what kind of trauma can happen in the subdural space?
subdural hematoma
what is the subdural space? example of trauma affecting this area?
artificial space created by separation of dura and arachnoid»_space; typically caused by trauma and nervous tissue dysfunction; subdural hematoma
what is meningitis?
inflammation of the meninges typically due to infection of the CSF
what is a lumbar puncture?
procedure used to obtain needle access into subarachnoid space, you obtain cerebral spinal fluid, inject contrast dyes, test pressure, etc…
where is the lumbar puncture performed in the back?
in the L3/L4 or L4/L5 intervertebral space, inferior to the conus medullaris, additionally we use the supracristal line that passes through L4 with the patient bent forward to open vertebrae and puncture more easily
what is the epidural space? why is this significant
a network of large thin walled blood vessels called the epidural venous plexus embedded within fatty tissue and so you can inject anesthetic here
what is the white matter?
composed of tracts of myelinated axons because of myelin
how is the white matter subdivided?
anterior, lateral, and posterior white columns
what are tracts?
bundles of nerve fibers with a common origin and destination that carry similar information
what are the tracts divided into?
ascending and descending tracts
the ascending tracts are always sensory or motor?
sensory
the descending tract are always sensory or motor?
motor
what is the gray matter?
forms central H-shape composed of unmyelinated axons plus motor and interneurons
what is the gray matter divided into?
dorsal horn, ventral horn, lateral horn
what is the dorsal horn divided into?
sensory functions
what is the ventral horn divided into?
motor functions
what is the lateral horn divided into?
only found in the thoracic region - autonomic/sympathetic function
what are spinal roots?
these emerge from the spinal cord at each vertebral level
what are the spinal roots divided into?
dorsal and ventral roots
what are the dorsal roots; what important structure can we also note associated with the dorsal roots?
contain predominantly afferent fibers (sensory); contain cell bodies of primary sensory neurons
what are the ventral roots?
contain efferent fibers (motor)
what do the ventral and dorsal roots fuse to form?
spinal nerves
how can we classify spinal nerves?
mixed
where do the ventral and dorsal roots fuse?
at the intervertebral foramen
how do the roots travel?
inferiorly before exiting vertebral column since spinal cord does not reach inferior end of spinal canal
the L2 - Co1 spinal roots inferior to conus medullaris on route to exit at proper intervertebral foramen are also known as?
cauda equina
the caudal equina is meninges or nervous tissue?
nervous tissue
the filum terminale is meninges or nervous tissue?
meninges
where do the spinal nerves exit from c1-c7?
they exit superior to vertebrae for which they are named
where do the spinal nerves exit for c8?
exit between c7 and T1
where do the spinal nerves exit from T1-Co1?
they exit inferior to the vertebrae for which they are named
what is the myotome?
all muscles supplied by a specific spinal nerve?
with respect to myotomes, when you have muscles supplied by multiple spinal nerves what happens when you have loss of a spinal nerve?
it will result in muscle weakness
what do myotomes help with in a clinical setting?
tests muscle strength and reflexes to determine what spinal nerves are affected or fine
what are dermatomes?
area of skin that that provides sensory information via a single set of spinal nerves
what is usually indicated if symptoms follow a dermatome (pain, loss of sensation or a rash)?
a pathology that involves the spinal nerve
what is the result if there is dermatome overlap?
sensation would be lessened not lost
