Skeletal muscle is one of the three types of muscle tissue present in the human body. It is attached to bones and is responsible for the voluntary control of the skeleton. Skeletal muscle tissue is composed of skeletal muscle cells, also known as muscle fibers. Skeletal muscle cells are multinucleated, elongated, and striated in appearance.

The interior of a skeletal muscle cell is packed with myofibrils which contain contractile proteins (myofilaments) that enable muscle contractions. The contractile proteins are arranged in repeating subunits known as sarcomeres. The sarcomeres give the skeletal muscle cells their striated appearance when viewed with a light microscope.

Cross section of skeletal muscle presents a stack of parallelly aligned, thick, red cylinders, called myofibrils, packed together inside a bigger tube, covered in a pink thin layer of the sarcolemma. Myofibrils cylinders are surrounded by light blue rings of triads, consisting of T tubules and terminal cisternae, and each ring is connected by a blue net of sarcoplasmic reticulum. The flattened spheres, called the nucleus, are placed underneath the layer of the sarcolemma.

Figure 1: Skeletal muscle cell.

Reference: Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436