The term 'chest muscles' refers to three different muscles: PECS (4 letters), Pectorals (9 letters), and ABS (3 letters). The Pectoralis Major, commonly known as the Pecs, is a large fan-shaped muscle located in the chest. It is responsible for adduction, flexion, and internal rotation of the shoulder joint. The Pectoralis Minor is a thin, triangular muscle located beneath the Pectoralis Major. It is responsible for protraction and depression of the shoulder joint. The Rectus Abdominis, commonly known as the Abs, is a long, flat muscle located in the abdomen. It is responsible for flexion of the spine and trunk. All three of these muscles are important for maintaining proper posture and stability of the chest and torso.