ABSTRACT
The muscular system forms the active part of the locomotor apparatus. There are several hundred muscles present in higher vertebrates. These muscles have evolved to perform general and specific functions that make various vertebrates unique. Having the ability to contract, enables the muscle to perform several functions in the vertebrate body such as movement in the environment and within body systems, heat generation and maintenance of body posture. Muscle also plays a major role in support of body weight by bracing the bones across joints and also in the general appearance of a vertebrate. The muscular activities are coordinated in their actions by the nervous and endocrine systems. Muscles also perform their activities together with accessory structures that include fasciae, bursae and tendon sheaths. Muscle fibers (cells) or myocytes develop from mesenchyme. The fibers have the ability to contract due to the presence of contractile proteins chiefly actin and myosin. The three types of muscle tissue found in vertebrates are smooth, skeletal and cardiac muscles that are associated with body organs, the skeleton and heart respectively.
