The muscle primarily responsible for retracting the scapula is the rhomboid muscle group, which includes the rhomboid major and rhomboid minor. Additionally, the trapezius muscle, specifically the middle fibers, also plays a significant role in this movement.
The rhomboids originate from the spinous processes of the thoracic vertebrae and attach to the medial border of the scapula. When these muscles contract, they pull the scapulae toward the spine, facilitating retraction. This action is essential for proper posture and shoulder mobility.
The trapezius, particularly the middle section, assists in this movement by pulling the scapulae toward the midline during activities that involve pulling the shoulder blades together, such as rowing or certain weightlifting exercises.
In summary, both the rhomboids and the middle trapezius are crucial for the retraction of the scapula, allowing for a range of upper body movements and contributing to overall shoulder health.