Question

Why do we need two muscles together to move a bone?

Answer 1

Hint:Muscles move body parts by getting a contract and then relax that is back to position. Muscles can pull bones however; they cannot push them back to the previous position, to do so they work in pairs of flexors and extensors.

Complete answer:A skeletal muscle typically works across a joint. It's connected to each bone on either facet of the joint by strong cords referred to as tendons. A tendon is made up of dense regular connective tissue that connects a muscle to a bone. Tendons are almost like ligaments, except that ligaments connect bone to bone. Once muscles contract, they get shorter. By contracting, muscles pull on bones and permit the body to move.
To move bones in opposite directions, pairs of muscles should also work in opposition. Every combined muscle works oppositely to move bones at the joints of the body. The muscle that contracts to cause a joint to bend is called the flexor muscle. The muscle that contracts to cause the joint to straighten is termed the extensor muscle. Once one muscle is contracted, the opposite muscle from the combine is usually elongated.
For example, the biceps and triceps muscles work along to permit you to bend and straighten your elbow. Once you wish to bend your elbow, your biceps muscle contracts and at a similar time, the triceps muscle relaxes. The biceps are that the flexor muscle, and therefore the triceps is that the extensor muscle of your elbow joint. Alternative muscles that work along with the area unit the musculus quadriceps femoris and hamstrings used to bend and straighten the knee, and therefore the pectorals and musculus trapezius used to move the arms and shoulders forward and backward.

Note:The quadriceps femoris muscle, also known as the quad muscle, is the strongest. It is located in the anterior portion of the thigh.
The trapezius muscle is a large, triangular, paired muscle located on the posterior of the neck and thorax. Together, this pair forms a trapezoid shape hence, named trapezius.