Arrangement of Skeletal Muscle | Movement Skeleton |

ARRANGEMENT OF SKELETAL MUSCLE FOR THE MOVEMENT SKELETON

Skeletal muscle has these parts:

1. Origin:

it is the end of the muscle that remains fixed during the contraction of muscles.

2. Insertion:

It is the end of the muscle that moves the bone.

3. Belly:

It is a thick part between origin and insertion. It shows contraction.

4. Connective tissue:

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

➤ Ligaments attach bone to bone and are slightly elastic.

➤ Tendons attach muscles to bones and are non-elastic.

MOVEMENT OF BONES

The majority of muscle tissues in our body are made up of skeletal muscle. The skeletal muscles pull on the tendons. The tendons then pull on bones produce movements. The tendon attaches the muscle with the bones. Two bones form joints. The first bone articulates with the second bone at joints. The muscles are attached to the first bone. These muscle passes across a joint and is attached to the other bones of the joints. This muscle contracts. 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 at joint. The relationship in which two muscles work against each other is called antagonistic.

The arrangement of muscles in elbow joints:

The movement of the elbow joint is the best example of muscle contraction. The contraction in elbow joints take place by biceps and triceps muscle The biceps bend the arm at the elbow joint, and triceps straightens it. These muscles have a following arrangement in the elbow joint:

1. Biceps brachii:

The biceps brachii muscle arises from 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.

2. Brachialis:

The brachialis is inserted in the ulna

3. Brachioradialis:

The brachioradialis ie inserted in the radius.

4. Triceps brachii:

It arises from the humorous and inserted into the ulna.

Mechanism of contraction in elbow joint:

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

➤ Bending of arm:

The contraction of the bicep, brachialis, and brachioradialis muscles lift

radius and ulna. Thus they bend the arm at the elbow.

➤ Straightening of arm:

The contraction of triceps straightens the arm at the elbow.