Our body gets its shape from the skeleton that supports it. The bones give the body strength and the muscles which are around the bones is what gives definition to the body, help in movement and store energy. The various muscles which are intertwined with tendons and nerves make the movement possible for the body. Different organs and parts need various types of muscles and depending upon the nature of requirement, striated or non striated or voluntary or involuntary type of muscles are present there. Since our whole body is a mass of muscles, their volume is indeed huge.
Muscles are made up of contractile tissues and perform the different involuntary and voluntary functions. Muscles are named so because, most of the muscles look like mouse and their tendons represents its tail. Mus means mouse in Latin. Biologically, muscle can be expressed as a contractile tissue which brings movement. It is also regarded as the body motor. These are the tissues which perform various functions so that some type of movement occurs. The different types of muscles in our body act as the power house as they supply energy or power to our body.
Although, the medical fraternity is still not in union regarding this figure, most experts believe that our body comprises of around 639 muscles which is a very vast network made up of tissues and fibers. Muscles are mainly responsible for the body movement.
Muscles are of three types. They are skeletal, cardiac and smooth muscles.
Skeletal muscles: These are also called as striated, striped, voluntary or somatic muscles. These are large in number and are attached to skeleton. Under microscope, these muscles display cross-striations and are the best form of differentiated muscle. Since these skeletal muscles are provided by somatic or cerebrospinal nerves they are under voluntary control. These muscles are controlled to the highest level by the cerebral cortex. Each muscle fiber consists of multiple nucleus and cylindrical cell. These contain myofibrils made from myofilaments. These myofilaments are of three various types: actin, myosin, tropomysosin and are the real contractile elements in the muscles. Examples of skeletal muscles are limbs and body wall, and bronchial muscles.
Smooth Muscles: These muscles are also known as unstriped, non striated, plain, visceral or involuntary muscle. These have been found to surround or encircle the viscera. These muscles are provided by the autonomic nerves and hence are not under voluntary control. Due to this, these muscles respond very slowly to the stimuli. But one of the highlighting features of these muscles is that they do not get tired easily under long contraction. They are also very little dependent on nervous control as they can contract automatically, rhythmically and most often spontaneously. Each muscle fiber is spindle shaped and elongated cell having a centrally placed nucleus. Examples of smooth muscles are blood bessesl and arrector pili skin muscles.
Cardiac muscles: The myocardium of heart is formed by cardiac muscles. It is striated and intermediate in structure and also involuntary. It also has a centrally located single nucleus which anastomoses with surrounding fibers at intercalated discs. In cardiac muscles the cross striations are comparatively less displayed than in skeletal muscles.
Each and every muscle in the body is designed keeping in mind the requirement of the body part where it is located. Muscle tissues can shorten or contract thereby making the internal and external body movements possible. Every small function like breathing, walking, talking, eating etc. need muscle tissue for performing.Skeletal muscles have the ability to respond instantly to the stimuli as it has the capacity to contract rapidly. But due to this it gets tired easily. The smooth muscles supply motor power which helps in regulating the functions like circulation, digestion, excretion or secretion related to internal environment. The cardiac muscles assist in the functioning of rhythmic and automatic contractions.