Voluntary muscle


Voluntary muscle


           Voluntary muscle is also called striated muscle. This type of muscle can be contracted and expanded according to desire. The different body parts get movement by it, thus, it is called voluntary muscle. This type of muscles is attached with bones, so it is also called skeletal muscles. 

         The voluntary muscles are made up many fibers, which remain connected with each other through connective tissues. Every muscular fibers are cylindrical in shape and made up with many myofibrils. It remains closed in rigid cell membrane formed by cytoplasm, known as sarcolemma. Many egg-shaped nucleuses present in every muscular fibers that remain situated just below the sarcolemma. In the muscular fibers, mitochondria and golgy body also present. In cytoplasm, uncountable myofibrils are found, known as carcostyles and a type of clean liquid substance also present, known as sarcoplasm. Every fibers are parallel to each other and when it is looked through microscope, black and white stripes appear clearly in alternative position on it. On the boundaries of every white stripe, lines of dots are seen. The opposite dots present in the both lines on black strip appear as connected with a fine line. It is situated with crossing the black stripe. Every white stripes are further divided at center into two parts by another line, which is called Krause’s membrane or Dobies line. The Dobies line divides every sacrostype in to small sections, called sarcomere.

          In this way, a black stripe (sarcous element) present in every sarcomeres and half-half white stripe present on both the sides. Every sarcous element remain further divided just in the middle through a line. Tubes present in it in transverse direction, which open mouth present in white stripe and closed rear end in Dobies line of black stripe. Sarcoplasm is filled in these tubes when the muscle contracts, due to which the black stripe is expanded due to filling sarcoplasm in it and the white strip is contracted.

          This type of muscles is thick in the middle and narrow at both the ends. These ends are called tendons. It is made up of fibrous tissue and only through these tendons; the muscle is attached with bone. There are two types of skeletal muscles that work opposite to each other. The muscles help in bending the body organs are known as flexor and those who help in straitening or expanding the body organs are known as extensor.