Rhomboid major muscle
It is one of the muscles in the axioscalpular muscle group and works in conjunction with the rhomboid minor, levator scapulae, and serratus anterior muscles to aid in the movement of the shoulder blades. The rhomboid major muscle acts to secure the scapula to the rib cage and aids in the rotation and lifting of the scapulae and shoulders. The development of this muscle helps to maintain good posture.
The rhomboid major is innervated by the dorsal scapular nerve (C5).
The rhomboid major gets its name from the rhombus, a four-sided shape with which it shares a similar shape. The major part of the name distinguishes it from the rhomboid minor muscle, which sits behind it.