tonus
[tō′nəs] Etymology: Gk,
tonos, stretching
1 also called
muscle tone. The normal state of balanced tension in the body tissues, especially the muscles. Partial contraction or alternate contraction and relaxation of neighboring fibers of a group of muscles hold the organ or the part of the body in a neutral functional position without fatigue. Tonus is essential for many normal body functions, such as holding the spine erect, the eyes open, and the jaw closed.
2 also called
tone. the state of the body tissues being strong and fit.