Gross and Microscopic Anatomy of Skeletal Muscle



Skeletal Muscle as an Organ

Each skeletal muscle is considered an organ, and like any other organ in the body, skeletal muscles are compilations of various tissues. If you remember, there are 4 major tissue types (muscular, connective, nervous, and epithelial tissues) and you find all 4 in a skeletal muscle. This first is obvious - muscular tissue composes the bulk of this organ. The second - connective tissue - is less obvious. Each skeletal muscle has 3 layers of connective tissue called "mysia" that surround various components of the skeletal muscle and compartmentalize the muscle. We will see all 3 of these during the next segment about skeletal muscle organization. The third type of tissue is nervous tissue. By now we know that skeletal muscle is controlled voluntarily which means there must be neurons closely associated with the organ (innervation) to stimulate contraction and production of force when the intent to do so arises. These neurons are called somatic motor neurons ... soma = body and motor = producing movement, so these neurons produce movement/locomotion of the body. The last tissue type is epithelial tissue, and this one may have you scratching your heads. We know that when we move our muscles it takes energy to create that movement; therefore, each skeletal muscle cell must be capable of creating energy. Each cell contains numerous mitochondria, the organelles responsible for creating energy in the form of ATP from oxygen and glucose, but the cell also needs a blood supply that can bring those nutrients to the cell. These blood vessels are lined with simple squamous epithelium... and there is your fourth and final major tissue type.



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