Trapezius Muscle

Actions of Trapezius Muscle:

Upper trapezius: elevation and upward rotation of the scapula
Middle trapezius: retraction of the scapula
Lower trapezius: depression and upward rotation of the scapula

Origin of Trapezius Muscle:

External occipital protuberance
Ligamentum nuchae
Spinous processes of C7 to T12

Insertion of Trapezius Muscle:

Upper trapezius: lateral clavicle and acromion
Middle trapezius: spine of the scapula
Lower trapezius: root of the spine of the scapula

Trapezius Muscle

The Trapezius is really a flat, triangular muscle, covering the upper as well as back part from the neck as well as shoulders. It arises in the external occipital protuberance and also the medial third from the superior nuchal line from the occipital bone, in the ligamentum nuchæ, the spinous procedure from the seventh cervical, and also the spinous processes of all the thoracic vertebræ, as well as in the corresponding portion from the supraspinal ligament. From this origin, the superior fibers proceed downward as well as lateralward, the inferior upward as well as lateralward, and also the middle horizontally; the superior fibers tend to be inserted into the posterior border from the lateral third from the clavicle; the middle fibers into the medial margin from the acromion, as well as into the superior lip from the posterior border from the spine from the scapula; the inferior fibers converge near the scapula, as well as end in an aponeurosis, which glides over the smooth triangular surface on the medial end from the spine, to be inserted into a tubercle at the apex of this smooth triangular surface. At its occipital origin, the Trapezius is connected towards the bone by a thin fibrous lamina, firmly adherent towards the skin. At the middle it’s connected towards the spinous processes by a broad semi-elliptical aponeurosis, which reaches in the sixth cervical towards the third thoracic vertebræ, as well as forms, with that from the opposite muscle, a tendinous ellipse. The rest from the muscle arises by numerous short tendinous fibers. The two Trapezius muscles together resemble a trapezium, or diamond-shaped quadrangle: two angles corresponding towards the shoulders; a third towards the occipital protuberance; and also the fourth towards the spinous procedure from the twelfth thoracic vertebra. (Henry Gray (1821–1865). Anatomy of the Human Body.)