The Muscular System

Introduction to Muscles

The muscular system is essential for producing movement in the human body. Muscles are specialized tissues that contract to generate force, enabling various bodily functions and locomotion.

• Three basic muscle types are found in the body:

  • Skeletal muscle

  • Cardiac muscle

  • Smooth muscle

Muscle Types

General Characteristics

Skeletal and smooth muscle cells are elongated and are often referred to as muscle fibers. Muscle contraction and shortening are due to the movement of microfilaments within these cells. All muscle types share specific terminology:

• Prefixes myo- and mys- refer to “muscle”

• Prefix sarco- refers to “flesh”

Comparison of Skeletal, Cardiac, and Smooth Muscles

The three muscle types differ in location, structure, and function. The following table summarizes their main characteristics:

Skeletal Muscle

Skeletal muscle is the most abundant muscle type in the body and is primarily responsible for voluntary movements.

• Most skeletal muscle fibers are attached by tendons to bones.

• Skeletal muscle cells are large, cigar-shaped, and multinucleate.

• Also known as striated muscle due to its striped appearance.

• Also known as voluntary muscle because it is the only muscle tissue subject to conscious control.

Connective Tissue Organization in Skeletal Muscle

Skeletal muscle cells are surrounded and bundled by connective tissue layers, which provide support and transmit force.

• Endomysium: Encloses a single muscle fiber.

• Perimysium: Wraps around a fascicle (bundle) of muscle fibers.

• Epimysium: Covers the entire skeletal muscle.

• Fascia: Located on the outside of the epimysium, further supporting the muscle.

Additional info:

• Tendons are cordlike structures composed mainly of collagen fibers, connecting muscle to bone and often crossing joints due to their toughness and small size.

• Aponeuroses are sheetlike structures that attach muscles indirectly to bones, cartilages, or connective tissue coverings.