Muscle · Shoulders

Rhomboid major

Musculus rhomboideus major

A flat sheet running diagonally down and out from the mid-back spine to the inner edge of the shoulder blade — the muscle that squeezes the shoulder blades together. It also tips the socket of the shoulder joint downward as it pulls, which is worth knowing: that is the opposite of what the arm needs in order to go overhead. It lies underneath the trapezius, so it is read through another muscle, and it is a classic site of the deep ache people point to between the spine and the shoulder blade after a long day at a desk.