The appearance of human muscular tissue is roughly comparable to the lean of butcher's meat. Muscle cells are arranged in fine elastic threads or fibers, wrapped together in bundles. Several bundles make a muscle. Every muscle is covered by a sheath, the ends of which form tendons attached to bones.
Muscles are attached to bones at the point that will give the best leverage. Muscles tend to work in pairs; for some movements groups of muscles are used. Muscles can be either voluntary or involuntary in nature. Each muscle is connected to the central nervous system by a motor nerve that carries messages from the brain, causing the muscle to contract.
Bursae are small sacs lined with synovial membrane and are found wherever pressure is exerted by ligaments over moving parts (singular noun - bursa).
Muscles make up approximately 40 percent of total weight. The heart is the hardest-working muscle in the body. It pumps 5 quarts of blood per minute and 2,000 gallons daily.
The gluteus maximus is the body’s largest muscle. It is in the buttocks and helps humans maintain an upright posture. The ear contains the smallest muscles in the body alongside the smallest bones. These muscles hold the inner ear together and are connected to the eardrum.
A muscle called the masseter in the jaw is the strongest muscle by weight. It allows the teeth to close with a force of up to 55 pounds on the incisors or 200 pounds on the molars.