Quick Facts
Origin: Spinous processes of T5-T12 vertebrae.
Insertion: Medial end of spine of scapula.
Action: Depresses, retracts, and upwardly rotates the pectoral (shoulder) girdle at acromioclavicular and sternoclavicular joints.
Innervation: Accessory nerve, anterior rami of third and fourth cervical nerves.
Arterial Supply: Dorsal scapular artery.
Related parts of the anatomy
Origin
The ascending part of trapezius muscle originates from the:
- spinous processes of the fifth to twelfth thoracic vertebrae;
- adjacent supraspinous ligaments.
Insertion
The fibers of the ascending part of trapezius muscle travel superolaterally along the upper back. They converge to a tendon, which inserts onto the medial half of the spine of the scapula.
Key Features & Anatomical Relations
Overall, the trapezius muscle is an extrinsic muscle of the back and is found in the posterior neck and upper back regions. It is a large, flat, triangular skeletal muscle that is composed of three parts:
- a descending part, which is the superior portion;
- a transverse part, which is the middle portion;
- an ascending part, which is the inferior portion.
The trapezius muscle is located:
- superficial to the semispinalis, spinotransversales, levator scapulae, rhomboid major, rhomboid minor, supraspinatus, and latissimus dorsi muscles;
- medial to the deltoid and infraspinatus muscles.
With regard to the ascending part of trapezius muscle specifically, it contributes to the formation of the triangle of auscultation, where the ascending part of trapezius muscle forms its superomedial boundary.
Actions & Testing
With regard to the ascending part of trapezius muscle specifically, it is involved in multiple actions:
- depresses the pectoral (shoulder) girdle at the acromioclavicular and sternoclavicular joints;
- retracts the pectoral girdle at the acromioclavicular and sternoclavicular joints;
- upwardly rotates the pectoral girdle at the acromioclavicular and sternoclavicular joints.
Overall, the trapezius muscle can be tested by elevating the pectoral girdle (i.e., shrugging the shoulders) against resistance, during which the muscle can be seen and palpated (Moore, Dalley and Agur, 2009).
List of Clinical Correlates
- Contributes to the formation of the triangle of auscultation
References
Moore, K. L., Dalley, A. F. and Agur, A. M. R. (2009) Clinically Oriented Anatomy. Lippincott Williams & Wilkins.
