Muscle is a soft tissue found in most animals.

The human body consists of over 600 muscles, which makes up between 1/3 and 1/2 of one's body weight and give the body its distinctive shape.


1   Etymology

The term muscle is derived from the Latin musculus meaning "little mouse" perhaps because of the shape of certain muscles or because contracting muscles look like mice moving under the skin.

2   Study

The study of muscles is called myology.

3   Function

Most large muscles, like the hamstrings and quadriceps, control motion. Other muscles, like the heart, and the muscles of the inner ear, perform other functions.

4   Classification

There are two types of muscle tissue recognized in vertebrates: striated muscle (= striped muscle) and smooth muscle, which is found in internal organs as the stomach, intestines, and bladder, and within the wall of blood vessels. Striated muscle further consists of skeletal muscle, and cardiac muscle. Only skeletal muscle is under voluntary control.

Striated muscle tissue is muscle tissue that has repeating sarcomeres, in contrast with smooth muscle tissue.

Smooth muscle is controlled by the autonomic nervous system; may either be generally inactive and then respond to neural stimulation or hormones or may be rhythmic.

Cardiac muscle is found in the heart, acts like rhythmic smooth muscle, modulated by neural activity and hormones

The brain controls muscles by sending impulses to "motor units", which is a motor neuron and the various actual muscle fibers that are activated by that neuron. This is called recruitment.

Humans have many, many motor units, which allows us for very intricate, refined movements. You can play guitar, dextrously use tools, and figure skate! But it also means your brain has to work a lot harder, and disperse signals a lot farther and wider, to fully activate a muscle. Comparatively, chimps have much fewer motor units, but the motor units they do have control many more fibers. So a single "contract" signal now applies to a MUCH wider group of muscles, which makes them appear stronger.

No one is precisely sure, but on a given basis, for a given task for a large muscle like your bicep, you may only use as little as 25% of the total muscle fibers. Even though it seems like you're trying your hardest, your brain simply isn't signalling all of the fibers inside that muscle.

To build up your traps do:

First three are most important.

The only real way we can increase our metabolism, unless we take drugs, is to lift weights and maintain or increase our lean mass