Transverse Part of Trapezius Muscle

Origin

The transverse part of trapezius muscle originates from the:

- spinous processes of the seventh cervical and first to fourth thoracic vertebrae;

- adjacent supraspinous ligaments.

Insertion

The fibers of the transverse part of trapezius muscle travel laterally along the upper back. They converge to a tendon, which inserts onto the:

- posterior half of acromion of the scapula;

- lateral half of 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 cervical 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.

Actions & Testing

The transverse part of trapezius muscle retracts the pectoral (shoulder) 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).

References

Moore, K. L., Dalley, A. F. and Agur, A. M. R. (2009) Clinically Oriented Anatomy. Lippincott Williams & Wilkins.