Muscle Tissue: Functions, Properties, Types, and Structure

Functions of Muscle Tissue

• Production of body movements
• Stabilization of posture
• Volume regulation of the body
• Movement of chemicals in the body
• Production of heat

Properties of Muscle Tissue

• Electrical excitability
• Contractility
• Extensibility
• Elasticity

Types of Muscle Tissue

There are three types of muscle tissue: striated skeletal, striated cardiac, and smooth.

• Striated skeletal muscle: Called skeletal because the function of these muscles is to move the bones; it often works on a voluntary basis.
• Heart muscle (myocardium): Is located in the heart and is part of its wall. Its movement is involuntary.
• Smooth muscle: Is part of the walls of blood vessels, airways, and some guts. Almost always, this type of muscle movement is involuntary.

Structure of Striated Skeletal Muscle

Each muscle fiber is enveloped by a very thin connective tissue called the endomysium. Many fibers form a bundle that is wrapped in turn by a connective tissue called the perimysium. The many fascicles that make up a muscle are surrounded by a connective tissue called the epimysium. The union of all packaging extends into the muscle, forming the tendon, and this, in turn, is attached to the periosteum.

Classification According to Muscle Form

• Long muscles: They are in the extremities.
• Wide muscles: They tend to be flattened. They are located in the thorax and abdomen. They can be variable, flat, curved, or triangular.
• Short muscles: They are in the joints, where the movements are slightly extended.
• Ring muscles: They are around a hole. They are called orbicular.

How Muscles Produce Movement

Skeletal muscles produce movements by exerting force on tendons, which in turn pull the bones and other structures, such as the skin. Most cross a joint and are fixed in the bone that is formed. The muscle involved in a particular movement is called the agonist.

Muscle Fatigue

If muscle cells are stimulated repeatedly without adequate periods of rest, the force of contraction decreases, and fatigue occurs.

Motor Unit

For a muscle to contract and move a bone, it must first be stimulated by nerve impulses. Many muscle cells are stimulated by fibers of a nerve cell called a motor neuron.