The term CHEST MUSCLES, FOR SHORT refers to the muscles located in the chest area. These muscles include the PECS (4 letters), PEC (3 letters), LATS (4 letters), DELTS (5 letters) and ABS (3 letters). The PECS are the pectoralis major and minor muscles, which are responsible for shoulder movement and chest expansion. The PEC is the pectoralis muscle, which is responsible for shoulder movement and chest expansion. The LATS are the latissimus dorsi muscles, which are responsible for shoulder movement and back extension. The DELTS are the deltoid muscles, which are responsible for shoulder movement and arm abduction. Finally, the ABS are the abdominal muscles, which are responsible for trunk flexion and stabilization.