Exam #4 Chapter 12 Flashcards
where is the spinal cord located?
it extends from the foramen magnum to L2
what does the spinal meninges do?
protect the spinal cord
what is the dura mater composed of?
an extremely tough outer layer of dense irregular connective tissue
where does the dura mater extend from?
the foramen magnum to about L2
where does the dura mater extend out?
the spinal nerves and continues as the ilium terminale
what is superficial to the dura mater?
the epidural space with adipose tissue
what is the arachnoid mater?
a thinner connective tissue layer
what do the fibers of the arachnoid mater extend to?
the pia mater
what does the fibers of the arachnoid mater that extend to the pia mater create?
the subarachnoid space
what does the subarachnoid contain?
cerebrospinal fluid (CSF)
what does the CSF do for the spinal cord?
it cushions it
what is the pia mater?
a delicate connective tissue layer adhering to the spinal cord surface
in the cross sections of the spinal cord, what does white matter surround and what does it contain?
gray matter with a central canal containing CSF
in the cross sections what does the white matter form?
3 columns containing tracts with axons carrying similar information/commands to/from similar locations in motor (descending) and sensory (ascending) tracts
in the cross sections of the spinal cord what is gray matter organized into?
nuclei
in the cross section of the spinal cord what does gray matter form?
1) anterior (ventral)
2) posterior (dorsal)
3) gray horns
4) small lateral gray horns in thoracic and upper regions
how are spinal nerves formed in the cross sections of the spinal cord?
by the fusion of two roots (dorsal and ventral)
what does the dorsal root carry?
incoming sensory axons
where are the cell bodies of sensory axons?
in the dorsal root ganglion
what do sensory neuron axons in the dorsal root do?
synapse in the posterior gray horn or ascend in nearby tracts
what does the ventral root contain?
outgoing motor axons
where are the cell bodies of somatic axons?
in the anterior gray horn
where are cell bodies of autonomic axons?
in the lateral gray horn
what is a reflex?
a rapid, automatic, stereotypical response to a stimulus
what does a reflex consist of? (6) (SSIMER)
1) a sensory receptor
2) sensory neuron
3) interneuron (usually)
4) motor neuron
5) effector
6) reflex arc
what do reflexes maintain?
homeostasis (autonomic and somatic)
what can reflexes be?
monosynaptic (single synapse) or polysynaptic (more complex)
where can reflexes integrate?
in the spinal cord or the brain
what is a stretch reflex?
a reflex that maintains posture and balance
what does striking the patellar ligament do?
stretches the quadriceps muscle
during a stretch reflex what does a muscle spindle do?
detect the stretch and its sensory neurons synapse on somatic motor neurons that innervates the quadriceps (monosynaptic) (fast)
besides synapsing on a somatic motor neuron what else does a stretch reflex do?
synapses with an interneuron that synapses with somatic motor neuron innervating the antagonist muscle (hamstrings) (reciprocal innervation)
what do stretch reflexes also send?
collaterals to the brain
why do stretch reflexes send collaterals to the brain?
to let you know what happened
what type of reflex is a golgi tendon reflex?
an inhibitory reflex
what do golgi tendon organs detect?
the stretch or tension on a tendon
what do golgi tendon reflexes prevent?
excessive force being applied to a tendon
when excessive force is detected what does the golgi tendon reflex do?
stimulate an inhibitory interneuron
what does the inhibitory interneuron that the golgi tendon reflex stimulated do?
relaxes the muscle exerting force on the tendon
besides simulating an inhibitory interneuron what else does the golgi tendon reflex stimulate?
a stimulatory interneuron
what does the stimulatory interneuron that the golgi tendon reflex stimulated cause?
the antagonist to contract (reciprocal innervation)
why are impulses sent to your brain during a golgi tendon reflex?
to inform you of what happened
what does the withdrawl (flexor) reflex do?
removes a limb from a painful stimulus
what can pain receptors be stimulated by during the withdrawal (flexor) reflex?
several harmful stimuli
when a stimulatory neuron is stimulated what will happen?
it will cause the flexor to contract, removing the limb part from the stimulus
what muscle will be inhibited during the withdrawal (flexor) reflex?
the antagonist muscle
what tells your brain about what happened during a withdrawl (flexor) reflex?
the collaterals to your brain
what is reciprocal innervation?
a phenomenon that allows opposing muscles to reinforce the efficiency of the withdrawal reflex.
where is the crossed extensor reflex seen?
in the lower limb
what will stepping on something cause?
a withdrawal reflex to remove your foot from the painful stimulus by simulating the flexor and inhibiting the antagonist
what will the cross extensor reflex use to maintain balance?
stimulatory signals will be sent to the extensor and inhibitory signals the antagonist in the other leg
what will let your brain know what happened in the crossed extensor reflex?
the collaterals
what does reflexes interact with?
other parts of your nervous system
what do reflex tests examine?
the integrity of the reflex arc as well as other interacting nervous system components
what are the connective tissue components of the spinal nerves/
1) endoneurium
2) perineurium
3) epineurium
what does the endoneurium surround?
each axon
what are the fascicles?
a bundle of axons
what does the perineurium surround?
the fascicles
what type of connective tissue is the epineurium?
fibrous
what does the epineurium surrund?
the netire nerve
How many pairs of spinal nerves exit the vertebral column?
31 pairs
where are spinal nerves C1-C7 located?
they emerge superior to their corresponding vertebrae
where are spinal nerves T1-L5 located?
they emerge inferior to their corresponding vertebrae
where is spinal nerve C8 located?
it emerges between C7 and T1
where are spinal nerves S1-S4 located?
they emerge from the sacrum
where are spinal nerves S5-Co1 located?
they emerge between the sacrum and coccyx
what are dermatomes?
the sensory input that spinal nerves receive from specific regions of our skin
what are spinal nerve branches called?
rami
what does the posterior (dorsal) rami serve?
the posterior trunk wall
what does the anterior (ventral) rami in the thoracic region form to serve?
intercostal nerves that serve the lateral and anterior trunk wall
what do the communicating rami carry?
autonomic motor fibers in the thoracic and upper lumbar regions ONLY
what do anterior (ventral) rami outside the thoracic region for?
plexuses
what are plexuses?
nerve networks
what do anterior rami of cervical, lumbar and sacral spinal nerves form?
plexuses that branch and rejoin before forming peripheral nerves
