Rhomboid major muscle

The rhomboid major muscle is a muscle in the back that connects the spine of the upper back to the scapula (shoulder blade). When contracted, the rhomboid major retracts the scapula.

Origin
The rhomboid major originates from the T2 to T5 thoracic vertebrae and the supraspinous ligament above these vertebrae.

Insertion
The rhomboid major inserts on the scapula, at the lower half of the posterior medial border at the base of the scapular spine.

Action
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.

Innervation
The rhomboid major is innervated by the dorsal scapular nerve (C5).

Blood supply
The main blood supply to this muscle is the dorsal scapular artery and it is innervated by the dorsal scapular nerve.

Word origin
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.