trapezius

noun

tra·​pe·​zi·​us trə-ˈpē-zē-əs 

tra-

plural trapezii trə-ˈpē-zē-ˌī 

tra-

also trapeziuses

: a large flat triangular superficial muscle of each side of the upper back

Examples of trapezius in a Sentence

Recent Examples on the Web

His second spot was noticed a year later on his back, in the area of his left upper trapezius muscle. —Alyssa Goldberg, USA Today, 12 May 2025

The trapezius, deltoid, tricep, and bicep muscles were poppin’, and so was her smile. —Victoria Uwumarogie, Essence, 2 Apr. 2025

When the deep stabilizing muscles of the shoulder, such as the lower trapezius, serratus anterior and rotator cuff, aren’t firing properly, larger muscles such as the upper trapezius (located at the side of the neck and top of the back) and pectoralis major (upper chest) tend to take over. —Dana Santas, CNN, 12 Mar. 2025

The latissimus dorsi and lower trapezius also aid in maintaining good posture. —Katrina Carter, Verywell Health, 13 Feb. 2025

Word History

Etymology

New Latin, from trapezium; from the pair on the back forming together the figure of a trapezium

First Known Use

circa 1704, in the meaning defined above

Medical Definition

trapezius

noun

tra·​pe·​zi·​us trə-ˈpē-zē-əs, tra- 

plural trapezii -zē-ˌī  also trapeziuses

: a large flat triangular superficial muscle of each side of the upper back that arises from the occipital bone, the ligamentum nuchae, and the spinous processes of the last cervical and all the thoracic vertebrae, is inserted into the outer part of the clavicle, the acromion, and the spine of the scapula, and serves chiefly to rotate the scapula so as to present the glenoid cavity upward