Final answer:
The pectoralis major is a muscle that covers much of the superior thorax and is located in the anterior thorax. Its primary functions are to flex, adduct, and medially rotate the arm at the shoulder joint.
Step-by-step explanation:
The pectoralis major is a thick, fan-shaped muscle that covers much of the superior thorax in the body.
It is located in the anterior thorax and is one of the main muscles that move the arm. Its primary functions are to flex, adduct, and medially rotate the arm at the shoulder joint.