The thyroid gland is a small butterfly-shaped gland in the neck, just in front of the windpipe (trachea). One of its main functions is to produce hormones that help regulate the body's metabolism (the process that turns food into energy). These hormones are called triiodothyronine (T3) and thyroxine (T4). Many of the body's functions slow down when the thyroid doesn't produce enough of these hormones.
Esophageal spasm is a disorder of the rhythmic waves of muscular contractions (peristalsis) of the esophagus. The cause of this disorder is not known. Symptoms include chest pain and difficulty swallowing.
There are two main types of esophageal spasm: 1  Diffuse esophageal spasm. This type of spasm is an irregular, uncoordinated squeezing of the muscles of the esophagus. 2  Nutcracker esophagus. This type of spasm squeezes the esophagus in a coordinated way, the same way food is moved down the esophagus normally.