Different types of muscles in the body perform different functions according to their type and location.
Muscles are the contractile tissues [Tissue that is able to contract] that are responsible for performing various voluntary and involuntary functions. Muscles can be regarded as motors of the body.
Muscles are so named because, many of them resemble a mouse, with their tendons representing the tail.
In Latin Mus stands for mouse.
By definition Muscle is a contractile tissue which brings about movements.
Types of Muscles
The muscles are of three types, skeletal, smooth and cardiac. Fourth type is myoepithelial cells which are specialized cells in sweat glands.
The characters of each type are summarized below.
Skeletal muscles are types of muscles which are most abundant and are found attached to skeleton. They are also called striped, striated, somatic, or voluntary muscles.
They exhibit cross-striations under microscope, and are considered to be the best differentiated form of muscle.
They are supplied by somatic (cerebrospinal) nerves, and, therefore, are under voluntary control, with certain exceptions.
They respond quickly to stimuli, being capable of rapid contractions, and help in adjusting the individual to external environment. They also get fatigued very easily.
Each muscle fibre of skeletal muscle is a multinucleated cylindrical cell, containing groups of myofibrils. Myofibrils are made up of myofilaments of three types (myosin, actin and tropomyosin). These are the actual contractile elements of the muscle.
Skeletal muscles are under highest nervous control of cerebral cortex and
Examples of this type of muscle are muscles of limbs and body wall, and bronchial muscles are examples of skeletal muscles.
This type of muscles are also called plain, unstriped, non-striated, visceral, or involuntary muscles. These muscles often encircle or surround the viscera
Smooth muscles do not exhibit cross-striations under microscope, being plain and smooth in form
They are supplied by autonomic nerves, and, therefore, are not under voluntary control and respond slowly to stimuli.
Smooth muscles are capable of sustained contraction, and, therefore, do not fatigue easily.
They provide motor power for regulating the internal environment related to digestion, circulation, secretion and excretion.
Smooth muscles are less dependent on nervous control, being capable of contracting automatically, spontaneously, and often rhythmically and each muscle fibre is an elongated, spindle-shaped cell, with a single nucleus placed centrally; the myofibrils show longitudinal striations.
Muscles of the blood vessels, and the arrector pili or erector pili muscles of the skin are examples of smooth muscles.
This type of muscles, as the name suggests are found in the heart. It is intermediate in structure, being striated and at the same time involuntary.
It is meant for automatic and rhythmic-contractions and each muscle fiber. These fibers have a single nucleus placed centrally which branches and anastomoses with the neighboring fibers at intercalated discs (apposed cell membranes). T
he cross-striations are less prominent than those in the skeletal muscle.
These are present at the bases of secretary acini of sweat gland, etc. These help in expulsion of secretion from the acini.
Out of the four kinds of muscles, the skeletal muscles are most abundant in the body. These are the only muscles which are dissected out in the dissection hall and studies individually.
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