Complex sentence: Pectoralis minor works in conjunction with the levator scapulae muscles and rhomboid muscle to downwardly rotate the scapulae, while the serratus anterior pulls forward to rotate the scapula downward and stabilize the shoulder during descent.
Split into simpler sentences: Pectoralis minor works in conjunction with the levator scapulae muscles and rhomboid muscle to downwardly rotate the scapulae. The serratus anterior pulls forward to rotate the scapula downward and stabilize the shoulder during descent.