Skeletal muscle is one of the three types of muscles in the human body- the others being visceral and cardiac muscles. In this lesson, skeletal muscles, its definition, structure, properties, functions, and types are explained in an easy but detailed way.
Skeletal Muscle is a muscle tissue that is attached to the bones and is involved in the functioning of different parts of the body. These muscles are also called as voluntary muscles as they come under the control of the nervous system in the body.
Structure of a Skeletal Muscle
The structural of Skeletal Muscle is as shown below-
This muscle is attached to the bones by an elastic tissue or collagen fibers called tendons. These tendons are comprised of connective tissues. The skeletal muscles consist of a bundle of muscle fibers naming fascicule. These fascicules are cylindrical in shape as shown in the figure. These muscle fibers are surrounded by blood vessels and a number of layers of other tissues enclosing it.
Each muscle fiber is line by plasma membrane naming sarcolemma reticulum. It encloses a cytoplasm called as sarcoplasm which has the endoplasmic reticulum. The muscle fibers consist of myofibrils which have two important proteins naming actin and myosin in it. The fascicule is enclosed by perimysium and the endomysium is the connective tissue that encloses the muscle fibers.
Properties of Skeletal Muscle
- Skeletal Muscles are long, thin and multinuclear fibers that consist of a regular pattern of fine red and white lines with a unique appearance.
- There are also called as striped or striated muscles due to their appearance.
- These muscles are under the control of the nervous system. Hence they are called as ‘Voluntary muscles’.
- A human body has about 700 skeletal muscles in it.
- These muscles are involved in locomotion and also in the movement of different parts of the body.
Functions of Skeletal Muscles
- They maintain the body position and the posture.
- They support organs, soft tissues and also some of the internal tissues.
- They help in the opening and closing of the urinary tract.
- They maintain the body temperature and also store nutrients in it.
- The Epimysium separates the muscles from the tissues and the organs.
- These muscles are mainly involved in the movement of different body parts such as hands, legs and etc.
Types of Skeletal Muscles
There are two types of skeletal muscles named as red and white muscles-
- Red Muscles
Red muscles are due to the red pigment called as myoglobin which is in high amounts in the human body. These muscles are smaller in diameter and have a large number of mitochondria in it. The myoglobin stores the oxygen which is used by the mitochondria for the synthesis of ATP. Red muscles have a large number of blood capillaries in it.
- White Muscles
Unlike the red muscles, the white muscles are bigger in diameter and have a small amount of myoglobin in it. They also have less number of mitochondria in it.
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