Rhomboid major muscle
From Wikipedia, the free encyclopedia
| Rhomboid major | |
|---|---|
 |
|
| Muscles connecting the upper extremity to the vertebral column. (Rhomboideus major visible at upper center right, near shoulder.) | |
| Latin | musculus rhomboideus major |
| Gray's | subject #121 434 |
| Origin | spinous processes of the T2 to T5 vertebrae |
| Insertion | medial border of the scapula, inferior to the insertion of rhomboid minor muscle |
| Artery | dorsal scapular artery |
| Nerve | dorsal scapular nerve (C4 and C5) |
| Actions | Retracts the scapula and rotates it to depress the glenoid cavity. It also fixes the scapula to the thoracic wall. |
| Antagonist | Serratus anterior muscle |
The rhomboid major is a muscle on the back that connects the scapula with the vertebrae of the spinal column.
Contents |
[edit] Structure
The rhomboid major arises from the spinous processes of the thoracic vertebrae T2 to T5 as well as the supraspinous ligament. It inserts on the medial border of the scapula, from about the level of the scapular spine to the scapula's inferior angle.
The rhomboid major is considered a superficial back muscle. It is deep to the trapezius, and is located directly inferior to the rhomboid minor. As the word rhomboid suggests, the rhomboid major is diamond-shaped. The major in its name indicates that it is the larger of the two rhomboids.
[edit] Innervation
The rhomboid major, like the rhomboid minor, is innervated by the ventral primary ramus via the dorsal scapular nerve (C5).
[edit] Actions
The rhomboid major helps to hold the scapula (and thus the upper limb) onto the ribcage. It also acts to retract the scapula, pulling it towards the vertebral column, and downwardly rotates the scapula with respect to the glenohumeral joint. It works collectively with the levator scapulae to elevate the medial border of the scapula.
[edit] Pathology for Scapular Instability
The muscles attached to the scapular are the only means of providing scapular stability, because the scapular is not directly attached to the torso. The scapula hangs between the clavicle and the upper arm. The rhomboideus major attaches the medial border of scapula to the spine. If the rhomboideus major is torn, wasted, or unable to contract, scapular instability may result.
The implications of scapular instability caused by the rhomboideus major include scapular winging during scapular protraction, excessive lateral rotation and depression of the scapula, as the antagonistic action of the rhomboideus major is absent. With scapular instability, movement in the upper extremity is limited as the scapula cannot guide the desired movement of the arm and shoulders. Pain, discomfort, and limited range of motion of the shoulder are possible implications scapular instability.
Treatment for scapular instability may include surgery followed by physical therapy. Physical therapy may consist of stretching and endurance exercises of the shoulder. Pilates and yoga have been also suggested as potential treatment and prevention of scapular instability.
[edit] Additional images
 Left scapula. Dorsal surface. |
 The scapular and circumflex arteries. |
 Surface anatomy of the back. |
[edit] See also
[edit] External links
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.
