Category: Biology Second Paper Lecture Sheet

Muscles and bones are connected to each other by tendons. Hence the movement of any organ depends on the rhythmic activity of the musculoskeletal system. Bone and muscle coordination in the knee joint is described below.
1. Flexor Muscles: Hamstring muscles and gastrocnemius muscles are required to bend the knee joint backwards. The hamstring muscle consists of three muscles. Biceps femoris, semimembranosus and semitendinosus. These muscles arise from the ischium of the pelvis and attach to the tibia. Their contraction brings the femur and tibia closer together and creates a fold in the knee joint.
2. Extensor muscle: The gastrocnemius muscle is the main muscle of the ball of the foot or ankle. It arises from the condyle of the femur and is attached to the calcaneus or ankle bone by the Achilles tendon. Their contraction brings the femur and tibia closer together and the knee joint bends backwards.
Intermittent contraction of muscle in normal or resting state is called muscle tension. Muscles are attached to bones by tendons. Each organ requires two types of muscles to move. These two muscles together are called antagonistic muscles. During limb movement, one muscle contracts and the other muscle stretches. That is, when one muscle is shortened, the opposite muscle is lengthened. Two types of muscles are attached to the humerus of the arm. Biceps muscle and triceps muscle. When raising the arm, the biceps muscle contracts and the triceps muscle stretches. At this time, no shock is felt in the muscles. Again, the biceps muscle expands and the triceps muscle contracts when the arm is lowered. Even at this time, the muscles do not need any push. Only the muscles are tense.
Muscle contains actin and myosin proteins. These proteins extend from one end of the muscle to the other and can stretch the muscle. This means that the muscles are only stretched, but not pushed.

Tonocity is the intermittent contraction of muscle in normal or resting state. Muscles are attached to bones by tendons. Each organ requires two types of muscles to move. These two muscles together are called antagonistic muscles. During limb movement, one muscle contracts and the other muscle stretches. That is, when one muscle is shortened, the opposite muscle is lengthened. Two types of muscles are attached to the humerus of the arm. Biceps muscle and triceps muscle. When raising the arm, the biceps muscle contracts and the triceps muscle stretches. At this time, no shock is felt in the muscles. Again, the biceps muscle expands and the triceps muscle contracts when the arm is lowered. At this time, the muscles do not feel any pressure. Only the muscles are tense.
Muscle contains actin and myosin proteins. These proteins extend from one end of the muscle to the other and can stretch the muscle. This means that the muscles are only stretched, but not pushed.

Tonicity is the characteristic of muscle tension or contraction. There are two types of muscle tension. namely-
1. High muscle tension: If there is excess tension in the muscles during normal rest, it is called high muscle tension
2. Low muscle tension: If the muscle tension is less than required in a normal resting state, it is called low muscle tension

Muscles that extend a body part backwards are called retractor muscles.

The muscle that extends a part of the body forward is called a protractor muscle.

The muscle that rotates any part of the body around or right-left is called rotator muscle. Rotation is the process of turning a part of the rotator cuff around or left and right. For example, the pronator muscle causes lateral rotation and the supinator muscle causes lateral rotation. The piriformis muscle helps rotate the femur.

The muscle that raises any part of the body is called levator muscle. The process of raising a limb of the levator muscle is called levitation. For example, the masseter muscle raises the jaw. Gastrocnemius muscle of knee, soleus muscle of foot etc.

The muscle that lowers any part of the body is called depressor muscle. The process by which a depressor muscle moves down a limb is called depression. For example, the mandibula muscle lowers the jaw.

The muscle that moves a part of the body away is called abductor muscle. Abduction is the movement of a part of the abductor muscle away. For example, the deltoid muscle moves an organ away.

The muscle that pulls any part of the body closer is called adductor muscle. The process of pulling an adductor muscle to a limb is called adduction. For example, the latissimus muscle pulls an organ closer.