Final answer:
The muscles responsible for protraction of the scapulothoracic (ST) joint include the serratus anterior and the pectoralis minor.
Step-by-step explanation:
The serratus anterior and the pectoralis minor are the muscles responsible for protracting the scapulothoracic joint by moving the scapula forward.
Protraction of the scapula occurs when the shoulder is moved forward, such as when pushing against something or throwing a ball.
The serratus anterior plays a significant role in this movement by pulling the scapula forward and around the rib cage.
The pectoralis minor assists in protracting the scapula by drawing it anteriorly and downward against the thoracic wall.