What are muscles?

A muscle is a soft tissue, composed of special fibers (known as muscle fibers) equipped with contractile capacity. The muscle fibers are formed from particular cells, called myocytes, which contain protein filaments of actin and myosin. As the protein filaments pass one another, their muscle activity produces a contraction that changes both the length and shape of the cell.

Inside the human body there are two major types of muscles: skeletal muscles (also known as “red” or “voluntary) which are controlled by the will of the subject; and smooth muscles (also known as “white” or “involuntary”), whose contractile activity is autonomous and independent of the subject. Skeletal muscle fibers occur in muscles which are attached to the skeleton while smooth muscle is found within the walls of organs and structures such as the stomach, intestines, uterus, bladder, and others. A final type of muscle is represented by the heart muscle, also called “cardiac muscle” or “myocardium”, whose properties are quite unusual. While its histological characteristics are similar to those of voluntary muscles, it works in fact as an involuntary muscle, or independently of the will of the subject.

Diseases that affect the muscles and/or their nervous control include neuromuscular diseases. Problems can lead to spasticity or paralysis, depending on the location and severity of the individual’s condition. Also, a large number of neurological disorders can lead to problems relating to movement or motor coordination. Seeking the most appropriate form of treatment is essential in order to prevent further complications from arising.


What are involuntary muscles?

From a histological point of view, involuntary muscles differ from voluntary muscles because the fibers from which they are composed do not consist of striations and thus, they are characterized by a structure almost completely uniform, defined as “smooth” musculature. Involuntary muscles are present in the walls of the digestive system, blood vessels, bronchi, uterus and bladder. Compared to striated muscles, smooth muscles contract and relax more slowly.


What are voluntary muscles?

Voluntary muscles are divided into two categories: superficial and deep. Superficial muscles are mimic muscles, present only at the neck and head. Deep muscles, on the other head, are divided into skeletal muscle (moving bones under conscious control) and muscles attached to other organs (or to organs such as the eyes and ears/ tongue and pharynx).


What function do muscles serve?

The main function of the muscular system is movement. Muscles are the only tissue in the body that have the ability to contract and therefore move the other parts of the body. They also perform different functions such as: enable the body to maintain posture and body position (sitting or standing positions), stabilize and strengthen joints as well as produce heat to maintain normal body temperature. 

The function of the involuntary muscles is to cause variations in shape or inner diameter of the organs (movement of substances inside the body and the exclusion of contents).Whether it is a facial expression, or movement of the hand, tongue or finger, the function of the voluntary muscles is always the same: to allow the subject to perform muscle movements controlled by their own will.