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Trapezius muscle
Last reviewed: 20.11.2021
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The trapezius muscle (M. Trapezius) is flat, triangular in shape, with a wide base facing the posterior middle line. The muscle occupies the upper back and the back region of the neck. It begins with short tendon bundles from the outer occipital protrusion, the medial third of the superior occipital line of the occipital bone, from the nuchal ligament, the spinous islets of the 7th cervical and all the thoracic vertebrae and from the bony ligament. From the places of origin, the muscle bundles are guided, significantly converging, laterally and are attached to the bones of the shoulder girdle. The upper muscle bundles pass downward and laterally, attach to the posterior surface of the outer third of the clavicle. The middle tufts are oriented horizontally to the outside and are attached to the acromion and blade awn. The lower fascicles of the muscle follow upward and laterally, pass into the tendon plate, which is attached to the scapular awn. The tendonous origin of the trapezius muscle is more pronounced at the level of the lower border of the neck, where the muscle has the greatest width. At the level of the spinous process of the VII cervical vertebra, the muscles of both sides form a well-pronounced tendon pad, which is found in the form of an impression in a living person.
The trapezius muscle is superficially all over, its upper lateral margin forms the posterior side of the lateral (lateral) triangle of the neck. The lower edge of the trapezius muscle covers the upper part of the latissimus muscle of the back and the medial edge of the scapula, forms the medial border of the so-called auscultation triangle. The lower border of this triangle runs along the upper edge of the latissimus muscle of the back, and the lateral line runs along the lower edge of the large diamond-shaped muscle (the size of the triangle increases with the arm bent forward in the shoulder joint when the scapula is displaced laterally and anteriorly).
Function: with simultaneous reduction of all parts of the trapezius muscle with a fixed spine, the scapula approaches the spine. The upper muscle tufts lift the scapula. The upper and lower muscle bundles, with a simultaneous contraction, rotate the scapula around the sagittal axis: the lower angle of the scapula is shifted forward and laterally, and the lateral angle is upward and medially. With a strengthened scapula and a contraction on both sides, the trapezius muscles unbend the cervical spine and tilt the head back. With one-sided contraction, the muscle turns the person in the opposite direction.
Innervation: additional nerve, cervical plexus (CIII-CIV).
Blood supply: transverse artery of the neck, suprascapular, occipital artery, posterior intercostal arteries.