The rhomboid muscle is a pair of muscles located in the upper back, connecting the spine to the shoulder blades. There are two rhomboid muscles: the rhomboid major and the rhomboid minor. Their primary function is to retract the scapulae, pulling the shoulder blades together and stabilizing them during arm movements. These muscles play a crucial role in maintaining good posture and supporting various upper body activities, such as lifting and pulling. Strengthening the rhomboids can help prevent shoulder injuries and improve overall upper body strength, making them important for athletes and active individuals.