There are seven cervical vertebrae, twelve thoracics, and five lumbar. Each level gained or lost is a victory in rehabilitation, but C4 is the big one.
Nerves run from the brain through the spinal cord to the body. They connect to the muscles and tissues of the body, allowing them to function. Some functions are within our control, like moving an arm, making a facial expression, or walking. Others are part of our unconscious system, things we take for granted, like breathing or swallowing saliva.
The fourth cervical vertebra is the level where nerves run to the diaphragm, the main muscle that allows us to breathe. It separates the chest from the abdomen, and when it contracts, the air is sucked into the lungs like a bellows. No contraction, no sucking, no breathing. People who survive spinal cord injuries above this level need ventilators or machines to breathe.
In front of a national audience on September 9, 2007, Kevin Everett, a pro football player, broke his neck at the level of C4. The bones surrounding his spinal cord had been damaged, and the ligaments holding everything stable were torn. The spinal canal - the space where the cord is supposed to have room to sit - was narrowed, and the cord stopped working. While he lay paralyzed on the field, the trainers, doctors, and paramedics at his side began doing the work that is practiced time and again. Immobilize the body so that no further movement or potential damage could occur, take the helmet off without levering the unstable neck, cool the body, get medication started, and quickly get Mr. Everett to a place where surgery could take place to stabilize the bones and decrease the swelling on the spinal cord.
Each spinal cord level is a victory. If they could save C4, then a lifetime of ventilators could be avoided. Get to C6 or C7, and arm and hand movement may allow writing and the use of a wheelchair. But spinal cord trauma is a waiting game. Time may allow swelling to go down and function to return, or the swelling may get worse.
As I write this, Mr. Everett's doctors are reporting that he can move his arms and legs and they are hopeful that he may walk again. This just 48 hours after warning that his injury was catastrophic and life-threatening. If one level is a victory, then this news is a Super Bowl.
Update: Kevin Everett is walking, and "...making strides every day..."