The rhomboid muscle is a skeletal muscle located in the upper back and connects the spine with the scapula, or shoulder blade. The rhomboid muscle is so named due to its rhomboid, or diamond-like, shape. There are two types of rhomboid muscle, the rhomboid major and rhomboid minor, which contract and relax to move the shoulder blades.
Skeletal muscle is one of three categories of muscle found in the body, along with cardiac and smooth muscle. Skeletal muscle is marked by striations, or parallel lines, caused by the ordered bundles of long muscle fibers. This type of muscle, unlike cardiac and smooth muscle, connects to bones and is, for the most part, under voluntary control.
The rhomboid major connects along the bottom part of the inner scapula on one end and articulates with the second through the fifth thoracic vertebrae on the other end. These vertebrae are the top set of bones in the part spine which connects with the ribcage. Each body ought to have two rhomboid major muscles, one for each side of the spine, that sit beneath, or deep, to the large trapezius muscles.
The rhomboid minor muscle also sits deep to the trapezius muscle and slightly separated and superior to the rhomboid major. Along the spine, it connects with the nuchal ligament, the 7th cervical vertebrae, or the bottommost bone in the spine of the neck, and the 1st thoracic vertebrae, or the topmost bone of the thorax. On its other end, the rhomboid minor connects with the upper portion of the vertebral border of the scapula. The vertebral border of the scapula is also called the medial border or medial margin and refers to the long, innermost side of the scapula closest to the spine.
Chronic stress, overuse of the shoulder, overhead exercise, or hunching may cause a muscle strain or spasm in the rhomboid muscle. A strain is characterized by pain or discomfort between the spine and scapula, particularly when moving or on the intake of breath. This is caused when the fibers of the rhomboid muscle are over-stretched or torn. A spasm, or an involuntary twitch of the muscle, may coincide with other symptoms of tenderness, tightness, or a knot in the muscle.
To prevent a strain or spasm in the rhomboid muscle, a person should warm up the back with light exercise and stretching before engaging in strenuous activities. One particularly effective stretch involves sitting with the feet out directly in front, bending the left knee, and crossing the left leg over the right. Then twist the back and cross the left arm to grab the left ankle, thus spreading the shoulder blades apart and stretching the left rhomboids. This may be repeated on the right side. To try a simpler stretch, cross the left arm over the body and hug it to the chest with the right arm, then repeat with the other arm.