Ourieff Jared, Scheckel Brent, Agarwal Amit
Arizona College of Osteopathic Medicine
University of Tennessee
The trapezius muscle is a large superficial back muscle that resembles a trapezoid. It extends from the external protuberance of the occipital bone to the lower thoracic vertebrae and laterally to the spine of the scapula. The trapezius has upper, middle, and lower groups of fibers. The ventral rami of C3 and C4 innervate the sensory functions of the trapezius. The spinal accessory nerve (cranial nerve XI) innervates the motor function of the trapezius. The function of the trapezius is to stabilize and move the scapula. The upper fibers can elevate and upwardly rotate the scapula and extend the neck. The middle fibers adduct (medially retract) the scapula. The lower fibers depress and assist the upper fibers in the upward rotation of the scapula. These motions allow for the scapula to rotate against the levator scapulae and the rhomboid muscles. This rotation, in conjunction with the deltoid muscle, is essential for throwing objects.
斜方肌是一块位于背部浅层的大肌肉，形似梯形。它从枕骨的外部隆起延伸至下胸椎，并向外侧延伸至肩胛骨的脊柱缘。斜方肌有上、中、下三组肌纤维。颈3和颈4的腹侧支支配斜方肌的感觉功能。副神经（颅神经XI）支配斜方肌的运动功能。斜方肌的功能是稳定和移动肩胛骨。上部肌纤维可上提并向上旋转肩胛骨，还能伸展颈部。中部肌纤维使肩胛骨内收（向内侧回缩）。下部肌纤维下压肩胛骨，并协助上部肌纤维向上旋转肩胛骨。这些动作使肩胛骨能够相对于肩胛提肌和菱形肌进行旋转。这种旋转与三角肌协同作用，对于投掷物体至关重要。
