What muscle group is described as flat, triangular muscles running from the upper back to the back of the neck?

The trapezius muscle group is a large, flat, and triangular muscle located in the upper back and neck region. It plays a significant role in various movements of the shoulder and neck, including the elevation, retraction, and rotation of the scapula. This muscle extends from the base of the skull down to the middle of the back, covering much of the upper back and sides of the neck. Its broad shape allows it to connect to several key areas, enabling a wide range of movement and support for the head and shoulders. The unique anatomical positioning and shape of the trapezius make it distinct from other muscle groups, like the deltoids, which are more rounded and located over the shoulder, the latissimus dorsi, which is a large muscle on the lower back, or the sternocleidomastoid, which runs down the side of the neck. Understanding the trapezius's structure and function is essential for comprehending its role in overall posture and movement.