Quick Facts
Origin: Spinous processes of T2-T5 vertebrae.
Insertion: Medial border of scapula inferior to spine of scapula.
Action: Retracts and downwardly rotates pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints.
Innervation: Dorsal scapular nerve (C4-C5).
Arterial Supply: Dorsal scapular artery, dorsal branches of upper posterior intercostal arteries.
Origin
The rhomboid major muscle originates from the:
- spinous processes of the second to fifth thoracic vertebrae;
- adjacent supraspinous ligaments.
Insertion
The fibers of the rhomboid major muscle travel inferolaterally and insert, via a broad tendon, onto the portion of the medial border of the scapula that lies inferior to the spine of the scapula.
Key Features & Anatomical Relations
The rhomboid major muscle is an extrinsic muscle of the back and is found in the upper back region. It is a thin, quadrilateral type of skeletal muscle.
It is located:
- posterior (superficial) to the erector spinae, splenius colli and serratus posterior superior muscles, and the dorsal scapular nerve;
- anterior (deep) to the trapezius muscle and the accessory nerve;
- medial to the scapula and infraspinatus muscle;
- inferior to the rhomboid minor muscle.
Actions & Testing
The rhomboid major muscle is involved in multiple actions:
- retracts the pectoral (shoulder) girdle at the acromioclavicular and sternoclavicular joints;
- downwardly rotates the pectoral girdle at the acromioclavicular and sternoclavicular joints;
- helps stabilize the scapula against the thoracic wall.
The rhomboid major muscle can be tested by holding the hand on the posterior aspect of the hip, then pushing the elbow backwards against resistance, during which the muscle can be palpated (Moore, Dalley and Agur, 2009).
References
Moore, K. L., Dalley, A. F. and Agur, A. M. R. (2009) Clinically Oriented Anatomy. Lippincott Williams & Wilkins.
