Rhomboid major muscle
A skeletal muscle on the back that connects the shoulder blade (scapula) with the vertebrae of the spinal column. It acts together with the rhomboid minor (a similar but slightly smaller muscle) to keep the scapula pressed against thoracic wall and to pull the shoulder blades together (a process called scapular retraction). The rhomboid major helps to hold the scapula (and thus the upper limb) onto the ribcage. Other muscles that perform this function include the serratus anterior and pectoralis minor.