MICROANATOMY

Detailed explanation-1: -When one of them contracts, the bone is pulled in that direction and the other muscle of the pair relaxes. To move the bone in the opposite direction, the relaxed muscle contracts and the first one relaxes. Thus two muscles have to work together to move a bone.

Detailed explanation-2: -Muscles work in pairs, when one muscle shortens the opposite muscle lengthens e.g. the biceps shortens to bend the elbow at the same time its opposite muscle, the triceps, lengthens to allow the movement to occur. Good working between pairs of muscle allows for smooth controlled movement.

Detailed explanation-3: -When signaled by a motor neuron, a skeletal muscle fiber contracts as the thin filaments are pulled and then slide past the thick filaments within the fiber’s sarcomeres. This process is known as the sliding filament model of muscle contraction (Figure 10.10).

Detailed explanation-4: -Skeletal muscles usually work in pairs. When one muscle contracts the other relaxes and vice versa. Pairs of muscles that work like this are called antagonistic muscles. For example, the muscles in the upper forearm are the biceps and the triceps are antagonistic.

Detailed explanation-5: -Muscles that work like this are called antagonistic pairs. In an antagonistic muscle pair as one muscle contracts the other muscle relaxes or lengthens. The muscle that is contracting is called the agonist and the muscle that is relaxing or lengthening is called the antagonist.