Question on spinal cord injuries

[Lyuokdea]

Kind of a random question I was thinking about earlier. From what little I know about quadriplegia, it is caused by spinal cord injuries high enough up the neck that all messages from the brain to the body are cut off. How then, does the patient not almost immediately die of heart stoppage due to signals not being sent from the brain stem to keep the heart beating? It seems unlikely that almost anybody would be able to be connected to a pacemaker fast enough to save their life in the event that they break their neck. I know that quadriplegics are not able to control any other involuntary muscle functions either, so it makes no sense that the Brain is still able to control the heart after injury.

Does the heart begin to provide it's own electrical signals in the case that the brain stem is cut off? Or does the heart actually stop after the spinal cord is cut, and emergency medicine is able to save the victims in time?

~Lyuokdea

 

[iansmith]

It is all about where the injurie took place. If I remember correctly, anything below the fifth cervical vertebrae will cause the lost of the function of the four limbs but most of the key function will remain (i.e. heart beat). Anything higher than the fifth cervical vertebrae will cause death and the heart to stop beating.

 

[hypatia]

There are several other types of nerve pathways.
The autonomic nervous system influences the activities of involuntary muscles{like the heart} and glands. Then there is the sympathetic nerves, which also sends the pump message to our hearts, controls{raises} blood pressure.
The parasympathetic nerves are considered the opposit of the sympathetic nerves. They tell your heart to slow down. These nerves start at the very base of your brain/spinal chord. After a spinal cord injury, the parasympathetic nerves that begin at the brain continue to work, even during the phase of spinal shock.
When spinal cord injury is at or above the T6 level the sympathetic nerves below the injury become disconnected from the nerves above. They continue to operate automatically once the period of spinal shock is over.

 

[somasimple]

There is also the cranial nerves.

 

[Moonbear]

It looks like the question has been mostly addressed. It's worth noting that sometimes a neck injury is fatal. The degree of paralysis depends on 1) the level of the injury (i.e., which vertebra(e) is/are affected), and 2) the extent of the injury (i.e., how much of the spinal cord was damaged; was the cord severed clean through, crushed, torn on one side but not the other; how many of the nerves passing through that level were spared).

In terms of the level of the injury, you can think of the spinal cord as somewhat like the telephone cables on your street. Each telephone pole would be analogous to each vertebra, were some cables are split off and provide signal to the houses just like spinal nerves split off and provide signals to some parts of the body. If a tree branch falls and damages the cable at the beginning of the street, all of the houses will lose service. If a tree branch falls and damages the cable in the middle of the street, only the houses with service beyond that point stop receiving phone signals.

The nerves that are needed to send signals to the heart branch off very high up in the spinal cord.

As for the extent of the injury, the nerves run through the spinal cord like bundles of cables. If you cut all of them, you cut off all body function controlled by nerves exiting below that point. But, you could just do a small amount of damage (say a broken vertebra...the bone itself...just nicks a small part of the spinal cord itself), and only affect a very small amount of function in the body, even if the injury is very high up.