Editing Trapezius (section)

==Structure==

[[File:Trapezius animation small2.gif|thumb|left|Position of trapezius and its parts:{{legend|orange|Superior fibers of the trapezius}}{{legend|red|Middle fibers of the trapezius}}{{legend|maroon|Inferior fibers of the trapezius}}]]
The ''superior'' or ''upper'' (or descending) fibers of the trapezius originate from the [[spinous process]] of C7, the [[external occipital protuberance]], the medial third of the [[superior nuchal line]] of the [[occipital bone]] (both in the back of the head), and the [[ligamentum nuchae]]. From this origin, they proceed downward and laterally to be inserted into the posterior border of the lateral third of the [[clavicle]].

The middle fibers, or transverse of the trapezius arise from the [[spinous process]] of the seventh cervical (both in the back of the neck), and the spinous processes of the first, second, and third [[thoracic vertebrae]].  They are inserted into the medial margin of the [[acromion]], and into the superior lip of the posterior border of the [[spine of the scapula]].

The ''inferior'' or ''lower'' (or ascending) fibers of the trapezius arise from the spinous processes of the remaining thoracic vertebrae (T4–T12). From this origin, they proceed upward and laterally to converge near the scapula and end in an [[aponeurosis]], which glides over the smooth triangular surface on the medial end of the spine, to be inserted into a tubercle at the apex of this smooth triangular surface.

At its occipital origin, the trapezius is connected to the bone by a thin fibrous lamina, firmly adherent to the skin. The superficial and deep [[epimysia]] are continuous with an investing deep fascia that encircles the neck and also contains both [[sternocleidomastoid]] muscles.

At the middle, the muscle is connected to the spinous processes by a broad semi-elliptical [[aponeurosis]], which reaches from the sixth cervical to the third thoracic vertebræ and forms, with that of the opposite muscle, a tendinous ellipse. The rest of the muscle arises by numerous short tendinous fibers.

It is possible to feel the muscles of the superior trapezius as they become active by holding a weight in one hand in front of the body and, with the other hand, touching the area between the shoulder and the neck.{{citation needed|date=October 2017}}

<gallery caption="Images of the trapezius and the bones to which it attaches, with muscular attachments shown in red">
File:Muscle trapèze.png|Trapezius muscle
File:Gray129.png|[[Occipital bone]]
File:Gray200.png|Left [[clavicle]]. Superior surface.
File:Gray203.png|Left [[scapula]]. Posterior surface.
</gallery>

===Innervation===
Motor function is supplied by the [[accessory nerve]].<ref name=":0">{{Citation|last=Bakkum|first=Barclay W.|title=Chapter 4 - Muscles That Influence the Spine|date=2014-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780323079549000049|work=Clinical Anatomy of the Spine, Spinal Cord, and Ans (Third Edition)|pages=98–134|editor-last=Cramer|editor-first=Gregory D.|place=Saint Louis|publisher=Mosby|language=en|isbn=978-0-323-07954-9|access-date=2021-01-08|last2=Cramer|first2=Gregory D.|editor2-last=Darby|editor2-first=Susan A.}}</ref> Sensation, including pain and the sense of joint position ([[proprioception]]), travel via the [[ventral rami]] of the [[Cervical spinal nerve 3|third (C3)]] and [[Cervical spinal nerve 4|fourth (C4)]] cervical [[Spinal nerve|spinal nerves]].<ref name=":0" /> Since it is a muscle of the upper limb, the trapezius is not innervated by [[dorsal rami]], despite being placed superficially in the back.