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Attachments, innervation and functions of the trapezius muscle.
Hello, everyone! It’s Matt from Kenhub, and in this tutorial, we will discuss the trapezius muscle.
The trapezius muscle is a triangular, flat muscle of the shoulder girdle.
It is supplied by the accessory nerve and the cervical plexus. Each of this pair of symmetrical muscles differentiates into three parts.
The descending or superior part runs from the occipital bone and nuchal ligament to the lateral third of the clavicle. The transverse or middle part originates from the spinal processes of the first to fourth thoracic vertebrae and inserts at the acromion. And the ascending or inferior part extends from the spinal processes of the fifth to twelfth thoracic vertebrae to the scapular spine.
The trapezius stabilizes and secures the shoulder blade at the thorax and fulfills numerous tasks. It moves the shoulder blade medially and rotates it outward. In addition, the descending part causes elevation of the scapula while the ascending part depresses this bone.
Furthermore, a unilateral contraction bends the head to the ipsilateral side, known as lateral flexion, whereas a bilateral contraction raises the head and the cervical vertebral column, known as dorsal flexion.