Striated Muscle

Striated muscle cells exhibit cross-striations due to the arrangement of myofilaments.

• Skeletal is attached to the bone. Moves the axial and appendicular skeleton, and allows changes in position and posture. Also moves eye muscles.
There are alternation dark and light bands: A or dark bands and I or light bands, which are bisected by narrow regions in the muscle. Where the I band is bisected by the dense Z line and the A band is bisected by the less dense H band. The H band is further bisected by a narrow dense line called the M line
• Motor innervation of skeletal muscle is at the neuromuscular function, where terminal branches of axons contact muscle fibers. Acetylcholine (ACh) is released into the synaptic cleft.
• Proprioceptors are encapsulated sensory receptors in muscles and tendons, part of the somatic sensory system. They provide information about the degree of muscle stretching/tension and coordinate opposing muscles. They also inform the CNS about the body’s position and movement in space.
• Visceral striated (in soft tissues), including the tongue, pharynx, upper part of esophagus, and lumbar diaphragm. Involved in speech, breathing, and swallowing.
• Cardiac is the heart wall muscle. It is found in the myocardium and in the base of large veins that empty into the heart. The long fibers branch and anastomose with neighbouring fibers. They are formed by individual mono and binucleated cells. Cardiac muscle has the same types and amounts of contractile filaments as skeletal muscle. It exhibits dense staining cross bands. The nuclei are located in the center of the cells (uni and binucleate).
• Intercalated discs include cross fibers in a linear fashion or in a fashion that resembles risers in a stairway. They represent sites where cardiac cells are attached to each other.
• Atrial muscle cells have natriuretic granules aggregated at the nuclear pole.