A LITTLE BIT OF NARRATIVE ON THE HUMAN BODY
VOLUNTARY SKELETAL MUSCLES
The skeletal muscles (almost all of them voluntary) are clearly the most numerous group of muscles in the human body. More than six hundred surround almost every millimeter of our body. They represent approximately 35% of body weight in women and 45% in men, and are the principal determinants of our physical form. They are also responsible for:
1). MOVEMENT AND POSTURE
2). PROTECTION
3). BODY HEAT
1) On the level of continuous contraction, known as muscle tone, it is the force that holds us upright and prepared to act, despite the forces of nature (gravity, wind).
2) Four layers of skeletal muscles connected to the ribcage and pelvic bones protect the internal organs of the abdomen.
3) By means of contractions and cellular respiration, the skeletal muscles play an important role in the equilibrium (homeostasis) of constant body temperature. If the hypothalamus (heat generating center of the brain) detects a fall in body temperature, it sends a signal to the muscles and they SHIVER. This increase in muscular activity generates heat, which raises the body´s temperature.
Every movement of the body requires various muscles to work together to initiate, maintain, and control the movement. The driving mechanism generates the main action, while the synergetic muscles contract with the mechanism to keep it going.
At the same time, the antagonistic opposing muscles have to remain relatively relaxed, which allows for the acting mechanism to complete a balanced action.
In the complex movement of throwing a basketball, three active mechanisms are involved: the deltoids in the shoulder, the biceps in the upper arm, and the round pronator in the forearm. The corresponding antagonist muscles are the major round, the upper-arm triceps, and the supinator. But keep in mind that if the muscles of the back and legs are not free to move, the throw will be defective.