Elizabeth Rodenberg, age 15, of Denton, Texas, for her question:
WHAT CONTROLS YOUR DIAPHRAGM?
The diaphragm is a movable wall that is made up mostly of muscle stretching across the inside of your body at about the level of the lowest rib. The muscle of the diaphragm is called a voluntary muscle which means that although breathing movements go on regularly without direction from the mind, we can control the diaphragm if we think about it.
We can stop the motion of the diaphragm for a while if hold our breath. A larger breath can be drawn if we wish, by contracting the diaphragm to a flatter position.
The muscular diaphragm is attached all around to the ribs and to a section of the spine. It is attached in front to the breastbone, more properly called the sternum.
Your body's cavity, between the neck and the legs, is divided into two main sections by your diaphragm. Above it is the chest cavity or thorax, which holds the lungs, heart and main blood vessels. Below the diaphragm is the abdominal cavity which holds the digestive and urinary organs.
The diaphragm's most important job, however, is being involved in the breathing process.
The phrenic nerve controls the movement of the diaphragm. This nerve passes down through the middle of the chest to the diaphragm. If this nerve is injured on either side, the diaphragm on that side does not move.
At one time doctors would destroy the nerve when they wanted a diseased lung to stop working. But this practice is seldom done in the treatment of infected lungs today. Now lung infections are treated with drugs that destroy the germs or by surgically removing the infected part.
When relaxed, the diaphragm forms a curve like a large cap. When it contracts or tightens, it flattens out in part. This contraction increases the space in the chest and air is drawn in. Other chest muscles help to keep the air moving in and out of the chest.
In the muscular diaphragm are a number of openings. The esophagus is a tube connecting the mouth and the stomach, for example, which passes through the diaphragm.
The aorta also passes through the diaphragm. The movement of the diaphragm helps to pump the blood back to the heart from the veins of the abdomen.
Also passing through the diaphragm are some of the body's nerves as well as lymphatic and thoracic ducts.
THe diaphragm is roughly elliptical. It slants upward, higher in front than in the rear.
When the diaphragm contracts, it exerts pressure on the abdomen which stimulates the stomach and and gives an assist in the digestive process.
A hiccup is caused by a spasmodic, involuntary contraction of the diaphragm.