Muscles That Are Prime Movers

The human body is made up of hundreds of muscles that must work together to allow for body movements. Although many of the body's muscles are small, and work in accordance with other muscles for proper movement, there are large muscles, within the body, that are primarily responsible for certain body movements. These major muscles are considered prime movers because they are the primary muscles involved in the activation of many of the major joints within the body.

The latissimus dorsi, more commonly referred to as the back muscles, is made up of two large muscles on the right and left posterior side of the upper body. The function of this muscle group is to allow for extension of the shoulder joint. In other words, by allowing for extension of the shoulder joint, adduction of the arm is possible. Generally, this muscle group is responsible for most of the pulling actions of the upper body.

The pectoral muscles, more commonly known as the chest muscle group, is made up of an upper and lower muscle group. It is located on the left and right side of the anterior side of the upper body. The primary function of this muscle group is the abduction of the arms and flexion of the shoulder joint. Ultimately, this muscle group is responsible for most of the pushing actions of the upper body.

The quadriceps is a muscle group located on the anterior, or front, of the upper thigh. It is made up of four separate muscles that must work together to allow for the extension of the knee joint. In other words, these muscles allow for the extension, or raising, of the lower leg.

The hamstrings muscle group is made up of three separate muscles. It is located on the posterior side, or back, of the upper thigh. The primary function of this muscle group is to allow for flexion of the knee joint. In other words, this muscle group allows for the bending of the knee and the lowering of the lower leg.

The deltoids, or shoulders, muscle group, is made up of three separate parts--the anterior, or front shoulder, the medial, or middle shoulder, and posterior, or back shoulder. These muscles work along with the muscles of the chest and the back, to allow for abduction and adduction of the arms and the extension and flexion of the shoulder joint. These muscles also act in accordance with the chest muscles to allow for pushing movements overhead.

The biceps and triceps are muscles that are located on the front and back of the upper arm. The biceps is made up of two separate muscle while the triceps is made up of three separate muscles. The primary responsibility of these muscles is the flexion and extension of the elbow joint, or movement of the lower arm. Ultimately, the biceps muscle group is responsible for the flexion of the elbow joint while the triceps muscle group is responsible for the extension of the elbow.