Deltoid muscle is found on the uppermost part of the arm. It covers the top of the shoulder joint. It resembles an equilateral triangle in shape. This muscle helps in the movement and rotation of the neck and mainly it provides stability to the shoulder blade. It helps in the lifting and twisting of the arm. The pectorals are located on the chest. There are two types of pectoral muscles: the pectoralis major and the pectoralis minor.
They create the bulk of the chest and are known as pecs. They extend from the shoulder to the breast bone. The contractions of the pectoralis major pull the upper arm bone and result in the lateral, vertical or rotational motion. The pectoralis minor muscle is located below the pectoralis major muscle. The pectorals control the movement of the arm and also help the chest muscles during deep breathing.
