Lecture 6 Flashcards
(21 cards)
What are the four different segments of the spinal cord?
Cervical (C1-C8), thoracic (T1-T12), lumbar (L1-L5), and Sacral (S1-S5)
Where does the spinal cord itself end?
The spinal cord ends in the L1-L2 region, from there spinal nerves continue down the hollow portions of the vertebrae
What happens if the spinal cord is completely cut?
There is a loss of this function for al parts of the body that the nerves control caudal to the cut, but the motor and sensory functions rostral remain fine
What does paraplegia mean?
Paralysis of both lower limbs
What does quadriplegia mean?
Paralysis of all four limbs
What is flaccid paralysis?
The muscles are in a state of no contraction, there is no reflexes or resistance to passive movements. There is also a general atrophy of the muscles
What is spastic/rigid paralysis?
An exaggeration of the reflexes and a high degree of tension in the muscles. Passive movements are difficult to initiate, but once you do the limb moves more easily
What is the lateral white matter in the spinal cord made up of?
The axons from neurons in the brain traveling down to make synapses on cells in the spinal cord
How does one voluntarily move their muscles?
Neurons in the brain that drive motor movements send axons down the spinal cord to synapse on the motor neurons, or onto neurons that synapse onto motor neurons, that allow one to voluntarily move their muscles
What is spinal shock?
For the first few days to weeks, there is flaccid paralysis with minimal spinal reflexes
What happens when spinal shock goes away?
Both spasticity and rigidity occur in the muscles innervated by nerves below the lesion
What is Brown Sequard Syndrome?
Paralysis of the lower muscles on the ipsilateral side, loss of touch pressure and position sense on the ipsilateral side, loss of pain and temperature on the contralateral side and parts of the ipsilateral side.
What is anterior spinal artery syndrome?
Flaccid paralysis and atrophy of the muscles in a band around the midsection, spastic/rigid paralysis of the legs, loss of pain and temperature of both legs, and normal sensations of limb position, touch and pressure on the skin.
How does touch pressure and position work?
Cell bodies in the dorsal root ganglion project their axons up the ipsilateral dorsal white matter to neurons in the brain
How does motor movement work?
Cell bodies in the brain project down the lateral white mater. Cell bodies in the ventral horn project out the spinal nerve to the muscles.
How does pain and temperature work?
Cell bodies in the dorsal rot ganglion project to cells in the dorsal horn of the spinal cord. Cells in the dorsal horn of the spinal cord project their axons across the midline and then up the contralateral ventro-lateral white matter to the brain
What is a slipped/herniated disk?
When a disk in the vertebrae swells up or moves up against the cord, it will put pressure on the cord and either block transmission of the action potentials and/or cause the axons to fire action potentials
What is whiplash?
Caused by a sudden hyper-extension/hyper-flexion of the neck muscles
What are bedsores?
Arise from having a body part in contact with the bed for prolonged periods of time, can be exacerbated by moisture which causes the skin to get broken
How is it possible for neurons to regrow their axons (excluding the spinal cord)
When a neuron gets hurt, it retracts its axon and the rest of the axon past the cut dies, however the Schwann cells that make up the myelin do not die, so it provides a tunnel for the new axon. If the cut is farther away from the body it also is more likely that the axon will grow back and if the person is younger that also creates a better likelihood.
Why don’t spinal cord axons regrow the same way that other axons will?
The Schwann cells don’t hang around and make little tunnels for the new axon, instead they make a major mess and release growth inhibitors that prevent the axons from growing back.
