Arrangement of Skeletal Muscles | Movement of Bone

Skeletal muscles are one of the most important muscles present in the body, which are attached to bones through tendons and ligaments. They are specifically linked to movement. Skeletal muscle has three parts;

1. Origin 
2. Insertion 
3. Belly 

Origin 

Skeletal muscles are attached to bones or sometimes to other muscles at two or more positions. If the attachment site of muscles is immovable or it is the end of the muscle that remains fixed during the contraction of muscles. 

Insertion 

As muscle attaches to bone or other muscles if it attaches to the moveable bone, which shows movement during any action. that moveable end is called the insertion point.

Belly

It is the thick part between origin and insertion. It consists of a group of skeletal muscle fibers It shows contraction and causes movement.

Connective tissue 

Connective tissues bind the muscles with other tissue. They hold the various organs together. it helps to maintain body form. Connective tissue fibrils have two specialized kinds,

• Ligament
• tendon 

Ligament 

The fibrous connective tissue that attaches bone to another bone is called a ligament. They are slightly elastic. Ligaments help to hold body structures and to keep them in a stable position. 

Tendon 

The connective tissues that serve to attach bones to muscles are called tendons. They are tough and flexible.

Movement of bone 

The majority of muscle tissues in our body are made up of skeletal muscle. muscles, ligaments, tendons, and bones work collectively to make a movement. Here is the procedure of bone movement in short steps.

1. The skeletal muscles pull on the tendon. 
2. The Tendon then pulls the bones to move. The tendon attaches the muscle to the bones. (Two bones form joints. The first bone articulates with the second bone.)
3. At joints, the muscles are attached to the first bone. These muscles pass across a joint and are attached to the other bones of the joint. This muscle contracts and this contraction moves one bone towards or away from the other bone. 

There are 650 muscles in the human body. Most of these muscles are present in pairs. These muscles work against each other by contraction etc joint.

The relationship in which two muscles work against each other is called antagonistic. 

Antagonistic movement means a pair of muscles work in a way that if one muscle moves, the other one will go in the opposite direction. If one muscle contracts, the other one relaxes.

Arrangement of muscle in elbow joint 

The moment of the elbow joint is the best example of muscle contraction. The contraction in elbow joints takes place by the biceps and triceps muscles. The biceps bends the arm at the elbow joint, and the triceps straightens it. 

These muscles have the following arrangement in the elbow joint:

Biceps Brachii:

 The biceps brachii muscle arises from the scapula by two heads. It is inserted into the medial surface of the radius bone. The other two muscles lie below the biceps brachii. The two muscles are Brachialis and Brachioradialis. 

Brachialis 

The Brachialis is inserted in the Ulna. 

Brachioradialis

It is inserted into the radius of the bone. 

Triceps Brachii

It arises from the humor and is inserted into the ulna. 

Mechanism of Contraction in Elbow join 

The bicep and tricep muscles are arranged antagonistically. In the antagonistic arrangement, one muscle reverses the effect of the other. But these must muscle do not contract simultaneously. 

Bending of Arm

The contraction of the biceps, brachialis, and brachiradilis muscles lift radius and ulna. thus they bend the arm at the elbow.

Straightening of Arm

The contraction of the triceps straightens the arm.

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