Question

When a person is paralyzed from the neck down, how do their heart and lungs continue to function?

Answer 1

The body can respond through a number of different ways to diseases, accidents and trauma. The loss of muscular function in any part of the body is known as paralysis. The most common reason for paralysis is stroke, spinal cord injury and head injury. It can be localized or generalized, partial or complete.

Complete answer:
An injury or damage in the spinal cord may be caused by trauma, stroke or accidental damage at any point along the spine. This results in the loss of motor and sensory function in the damaged area. When the paralysis affects the part of the body from neck down is known as quadriplegia. Paralysis mainly occurs due to lesions on the spinal cord due to injury and as a result, the spinal cord stops or impaired to send and receive signals from the brain to other parts of the body. Thus, injuries in the spinal cord or brain may cause the onset of paralysis.

However, the paralysis can affect the functioning of the muscles but it may occur that the heart and lungs can function to some extent. This occurs due to the vagus nerve. The vagus nerve originates from the medulla oblongata. It then travels through the jugular foramen and down bilaterally the lateral aspect of the neck. It gives off several branches which provide nerve function to the important organs such as the larynx, heart, lungs, liver, kidneys, stomach, spleen and intestines.

The vagus nerve partially controls the parasympathetic innervation of the heart. This activity of the vagus is shared by the thoracic ganglia. Vagal and spinal ganglionic nerves together cause the lowering of the heart rate. The right vagus branch innervates the sinoatrial node of the heart. In case of hyper stimulation, the left vagal branch causes the heart to block at the atrioventricular node. Thus, the vagus nerve is responsible for important tasks as heart rate.

In addition to this, the vagus nerve also controls the breathing rate as it communicates with the diaphragm. The major nerves involved in respiration include the phrenic nerve, vagus nerve, and posterior thoracic nerves

Note: Paralysis is the condition of no or decreased motor and sensory function in some or most of the parts of the body. It may be caused by trauma, accidents, stroke or injury and may impair various activities of the body. However, in these conditions the heart and the lungs can continue to function through the vagus nerve.