Digastric muscle cornu of the hyoid bone; this is termed the suprahyoid aponeurosis. The digastricus (digastric muscle) consists of two muscular bellies united by an intermediate rounded tendon. The two bellies of the digastric muscle have different embryological origins, and are supplied by different cranial nerves. Each person has a right and left digastric muscle. In most anatomical discussions, the singular is used to refer to a muscle, even when each person actually has two of that muscle—one on the right side, and another on the left. For example, we speak of the deltoid, even though there is one deltoid in each
Muscle and endoneurium). This same bundles-within-bundles structure is replicated within the muscle cells. Within the cells of the muscle are myofibrils, which themselves are bundles of protein filaments. The term "myofibril" should not be confused with "myofiber", which is a simply another name for a muscle cell. Myofibrils are complex strands of several kinds of protein filaments organized together into repeating units called sarcomeres. The striated appearance of both skeletal and cardiac muscle results from the regular pattern of sarcomeres within their cells. Although both of these types of muscle contain sarcomeres, the fibers in cardiac muscle are typically branched to