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102 Cards in this Set

  • Front
  • Back
number of cervical spinal nerve pairs
8
number of thoracic spinal nerve pairs
12
number of lumbar spinal nerve pairs
5
number of sacral spinal nerve pairs
5
number of coccygeal spinal nerve pairs
1
Why does the spinal cord have a cervical enlargement?
It contains the nerves of the upper limbs
Why does the spinal cord have a lumbar enlargement?
It gives rise to nerves of the pelvic region and lower limbs
Why are there 8 cervical spinal nerves?
Because the C1 vertebrae has an extra spinal nerve that is above the C1 vertebrae, when normally they all have spinal nerves below
medullary cone
inferior to the lumbar enlargement the cord tapers to this point
cauda equina
the lumbar enlargement and medullary cone give off a bundle of nerve roots that occupy the vertebral canal from L2-S5. These innervate the pelvic organs and lower limbs
Gray matter
contains nerve cell bodies, dendrites, neuroglia and unmyelinated axons
White matter
Contains myelinated nerve fibers
Posterior and anterior horns
made of gray matter
What are the posterior and anterior horns connected by?
Connected by gray commissure which forms the central canal in the middle and it consists of cerebrospinal fluid
What type of neurons are located in the anterior horns?
motor
What type of neurons are located in the posterior horns?
sensory
Which horn (anterior or posterior) is the cell body (soma) of the sensory neurons?
posterior
White matter contains?
myelinated nerve fibers. it consists of bundles of axons that course up and down the cord and provide avenues of communicated between the different levels of the CNS.
nerve fiber
nerve process (axon or dendrite)
Nerve
bundle of nerve fibers in PNS (mixed-combo of sensory and motor)
tract
bundle of nerve fibers in the CNS (mixed-combo of sensory and motor)
mixed
combo of sensory and motor
ganglion
cluster of neuronal cells bodies in PNS
nucleus
cluster of neuronal cells bodies in CNS
The brain and spinal cord are enclosed in three connective tissue membranes called
meninges
dura matter
most superficial sheath, it is a tough collagenous membrane about as thick as a rubber kitchen glove
epidural space
the space between the sheath and vertebral bone that is occupied by blood vessels, adipose tissue, and loose connective tissue
arachnoid matter
middle sheath that is closest to the dura matter
subarachnoid space
the gap between the arachnoid membrane and the pia matter that is filled with cerebrospinal fluid
From which space is a spinal tap taken? (vertebral and spinal)
Between the spinous process of L3 and L4 and CSF can be ejected from the subarachnoid space
Which space is an epidural anesthetic injected?
Into the epidural space where there is fat and it will hit the spinal nerves around it. Used during labor and delivery and surgery in the pelvis or leg
Which space is a spinal anesthetic injected?
Goes into the spinal cord in the space inferior to L1-L2 (below cord) in the subarachnoid space. Used for genital, urologic, or lower body procedures
Which vertebral level is safest place to inject anesthetic or take a sample of CSF?
Between the spinous processes of L3 and L4 because the spinal cord doesnt extend this far and is not exposed to injury
decussation
when the spinal nerve tracts cross over from the left side of the body to the right side, or vice versa
contralateral
When the origin and destination of the tract are on opposite sides of the body
ipsilateral
When a tract does not decussate, so the origin and destination of its fibers are on the same side of the body
ascending tracts
carry sensory information up the cord
descending tracts
conduct motor impulses down
1st order neuron
detects a stimulus and conducts a signal to the spinal cord or brainstem
2nd order neuron
continues to the thalamus at the upper end of the brainstem
3rd order
carries the signal the rest of the way to the sensory region of the cerebral cortex
sensory
ascending tract
motor
descending tract
upper motor neurons
neurons that bring messages from the brain down to the spinal cord
lower motor neurons
Neurons that branch out from the spinal cord and the muscles and tissues of the body
nerve fiber
Nerve process (axon or dendrite)
Nerve
Bundle of nerve fibers in the PNS (mixed)
Tract
Bundle of nerve fibers in the CNS (mixed)
Mixed
Combination of motor and sensory nerve fibers
Ganglion
cluster of neuronal cell bodies in PNS
Nucleus
Cluster of neuronal cell bodies in the CNS
Ascending tract sends what type of information?
Sensory info to the brain
Descending tract sends what type of information?
Motor info to the spinal cord and limbs
What is the order of sensory neurons traveling up the general spinal tract?
Spinal cord, medulla, midbrain, brain
What type of signals does the spinothalamic tract send?
Carries signals for pain, temperature, pressure, tickle, itch, and light or crude touch.
Where do 1st order neurons end in the spinothalamic tract?
In the dorsal horn of the spinal cord
What do the second order neurons in the spinothalamic tract do?
they decussate to the opposite side and lead all the way to the thalamus
Where do the 2nd and 3rd order neurons synapse?
In the thalamus and continue to the cerebral cortex
What happens when you damage the spinothalamic tract?
you lose the ability to sense all those specific things (touch, tickle, itch, temperature, pain and pressure) in a certain area
What is the descending tract?
carries motor signals down the brainstem and spinal cord and involves two neurons called the upper and lower motor neurons
upper motor neuron
Begins with a soma in the cerebral cortex or brainstem and has an axon that terminates on the lower motor neuron
lower motor neuron
the axon in the brain or spinal cord leads the rest of the way to the muscle or target organ
Corticospinal tract
Carries motor signals from the cerebral cortex for precise, finely coordinated limb movements`
Where does the UMN decussate in the corticospinal tract?
in the lower medulla and form the lateral (ventral) corticospinal tract on the contralateral side of the spinal cord
Reflex arc pathway
From a sensory nerve ending to the spinal cord or brainstem and back to a skeletal muscle
During a reflex reaction is information sent to the brain?
Yes, but it is not involved in the actual reflex motion. This information signals pain and it is relayed slower to the brain
Somatic reflexes
responses of skeletal muscle, such as quick withdrawl of your hand form a stove
Stretch reflex
Increased muscle tension in response to stretch. Serves to maintain equilibrium and posture, stabilize joints, and make joints smoother and better coordinated. It is a monosynaptic spinal reflex so there is no interneuron involved and the afferent neuron synapses directly with an efferent neuron
Is the spinal cord is severed at a higher area like T1 will the patient still have a stretch reflex?
Yes because the signals do not need to go to the brain
Flaccid paralysis
No reflexes occurs at the lower motor neurons
Spastic paralysis
exaggerated reflexes, no inhibitory control from UMN
What part of the spinal cord is damaged with ALS?
Degenerating of the upper and lower motor neurons. It is a paralysis of voluntary muscles. Also known as Lou Gehrig's disease. The person is cognitively intact then slowly start losing motor function, breathing ability and they can have respiratory failure
What part of the spinal cord is damaged with polio?
Degeneration of the lower motor neurons. Occurs in the ventral horn and causes paralysis.
Sensory nerves are______
Posterior or dorsal
Motor nerves are _____
Anterior or ventral
Dorsal root ganglion
the dorsal root expands into this which contains the somas of the sensory neurons carrying signals to the spinal cord
Immediately after emerging from the intervertebral foramen the nerve divides into what?
a dorsal and venral ramus
What does the dorsal ramus innervate?
the muscles and joints in that region of the spine and skin of the back
What does the ventral ramus innervate?
The ventral and lateral skin and muscles of the trunk and gives rise to the nerves of the limbs
What do the anterior rami of the spinal cord levels T1-T11 form?
Intercostal nerves between the ribs which innervate the intercostal muscles for breathing, the abdominal muscles and the skin on the anterior and lateral side of the body
The book calls the T12 anterior rami an intercostal nerve, why is this incorrect?
Its more correct name is subcostal nerve
Dermatome
An area of the skin innervated by a specific spinal nerve
Where does the shingles virus remain latent?
dorsal root ganglia
When the shingles virus becomes reinactivated what happens?
If the immune system is compromised the virus can travel down the sensory nerves by axonal transport and cause shingles.
What are the signs of shingles?
a painful trail of skin discoloration and fluid filled vesicles along the path of the nerve
Nerve plexus
group of anterior rami traveling together
What are the 4 nerve plexuses?
Cervical, brachial, lumbar, and sacral
Cervical plexus
anterior rami of C1-C5, innervates head, neck and upper shoulders and the phrenic nerve for this rami from C3-C5
Phrenic nerve
Roots from C3-C5 brings motor nerves to the diaphragm enabling you to breath
Brachial plexus
Ventral rami of spinal nerves C5-T1 (C4-T2), innervates arms and shoulders. It also has the ulnar nerve which is our funny bone
The brachial plexus travels deep to which bone?
The clavicle
Damage to the brachial plexus would result in
Damage to the lower motor neurons and it would cause flaccid paralysis
Sacral plexus
Ventral rami of spinal nerve L4-S4, innervates the gluteal region, posterior thigh and leg and contains the sciatic nerve
Sciatica
Injury to the sciatic nerve. IVD herniation, osteoarthritis, damage along pathways. Feel numbness and pain down the back of their leg caused by pressure on that area for a prolonged time.
Complete severance of the spinal cord
Causes immediate loss of motor control at and below the level of injury. Victims lose all sensation from the level of injury and below
Spinal shock
The early symptoms of spinal injury where the muscles below the level of injury exhibit flaccid paralysis (inability to contract) and an absence of reflexes because of the lack of stimulation at the higher level of the CNS.
Flaccid paralysis is due to damage in the
LMN
Spastic paralysis is due to damage in the
UMN
Spastic paralysis
Starts with chronic flexion of the hips and knees and progresses to a state in which the limbs become straight and rigid
Paraplegia
paralysis of both of the lower limbs resulting in spinal cord lesion at levels T1 to L1
quadriplegia
the paralysis of all four limbs resulting from lesions above level C5
hemiplegia
paralysis of one side of the body, usually resulting in spinal cord injuries but not a stroke from C5 to C7