Also called rhomboid major and minor, muscle between the shoulder blades
The rhomboids are two flat muscles under the trapezius, between the spine and the inner edge of each shoulder blade: the smaller rhomboid minor at the base of the neck and the rhomboid major below it.
They squeeze the shoulder blades together and, with the serratus anterior, hold them flat against the ribs; pulling, throwing and overhead movements all lean on them.
Rows were part of a scapular programme proposed from EMG of eight shoulder-blade muscles including the rhomboids. No study has measured which exercises work it hardest; these load its actions.
Entrapment or injury of their nerve, sometimes in overhead sports, causes aching along the inner edge of the shoulder blade, odd shoulder movement and a subtle winging. It is often missed and is usually treated without surgery.
Anatomy and movement education, not a diagnosis or treatment plan. If you have pain that follows an injury, is severe or getting worse, or comes with numbness, weakness or swelling, get it assessed. Health disclaimer.