The rhomboid major is a muscle located in the upper back that is used to connect the spine to the scapula. Its actions are to help secure the scapula as well as to pull it toward the spine. The muscle is also used to rotate the scapula downward. Due to its important role in stabilizing the scapula, if the rhomboid major is weak or isn’t providing the required support then it can lead to a condition known as scapular instability.
The origin of the rhomboid major is on the thoracic vertebrae. It also originates at the suprasinous ligament. From there it runs outward and downward before attaching to the scapula. The innervation of the muscle is via the scapular dorsal nerve.
As the name suggest, the rhomboid major is shaped like a diamond. There are two rhomboid muscles and the major is the larger and more powerful. The rhomboid major is a superficial muscle in the back and is located underneath a muscle known as the trapezius.
The main action of the rhomboid major is to support the scapula and hold it in position in relation to the ribcage. This is an important role and there are many negative consequences should this not occur correctly. Aside from support the muscle is also used to rotate the scapula in a downward direction, which it does with the help of other surrounding muscles.
The rhomboid minor is located above the major and is used to adduct the scapula. It also has the action of rotating the scapula laterally. The rhomboid minor has the same innervation as the major muscle although is much smaller.
The only reason that the scapula is held in position is due to the muscles that attach to it. The rhomboid muscles, for this reason, are essential in providing stability as the scapula is not attached to the body in any other way. When the rhomboid major is damaged or becomes weak, then instability in the region may occur, which can cause a number of different problems. For example, the scapula cannot move correctly when there is instability, which will cause pain along with a decreased range of motion.
There are several different possible treatments for scapula instability. The first is physical therapy, which can focus on helping the muscle to heal and promote increased strength. Surgery may also be required in some situations. Alternative treatments such as yoga may also be useful.