The process of swallowing a sword involves more than just lining everything up and letting gravity do its work. In order to successfully swallow a sword, a performer must learn to relax muscles that are typically not under voluntary control. These include the upper and lower esophageal sphincters and the muscles of the esophagus that are involved in peristalsis.
He must also make the performance look easy, which can be a challenge. If you have ever swallowed a mouthful of food that was too large or not thoroughly chewed, you know how sensitive your esophagus can be. A sword swallower must move a cold, rigid sword down the entire length of his throat and esophagus without showing any discomfort.
The human body also has a defense mechanism that has the sole function of preventing everything but chewed, swallowed food from entering the throat — the gag reflex. When you accidentally touch the back of your throat with your toothbrush and involuntarily gag, you've activated this reflex. In some people, the gag reflex is quite sensitive and can be activated by touching the back of the mouth. In others, the gag reflex is minimal.
A successful sword swallower has to learn to ignore his gag reflex. This is not easy. Reflexes are involuntary — they happen without deliberate effort or thought. Your reflexes allow you to jerk your hand away from a hot stove, and they're also involved in the involuntary portions of body processes like urinating. All of these reflexes are vital to survival, and all of them happen without the involvement of your conscious mind.
Reflexes involve several physiological components that combine to form a reflex arc. Here's what happens:
- A receptor, or nerve ending, detects a threat or an event that requires the body's immediate attention.
- A nerve, or neuron, carries the receptor's information to the central nervous system (CNS).
- The integration center in the CNS determines the body's response.
- A motor neuron carries the integrating center's instruction to the appropriate part of your body.
- An effector makes a necessary change to what's going on in your body.
In the case of your gag reflex, nerve endings in the back of your throat detect an intrusive object. This generates nerve impulses, which a neuron carries to the integration center in your brain stem. The brain stem, using a motor neuron, instructs the muscles in your throat — the effectors — to contract. The result is a retch intended to force foreign objects out of the throat and mouth. All of this is involuntary and happens in an instant.
Learning to ignore an involuntary process takes a tremendous amount of practice. In the case of sword swallowing, it generally involves deliberately activating the gag reflex over and over. The process can cause vomiting and considerable discomfort. It also dulls or removes a process intended to protect the person from harm. This is one of the many reasons why sword swallowing is dangerous. We'll look at some of the hazards of sword swallowing in the next section.