Editing Trapezius

{{Short description|Muscle between the lower spine and the shoulder blade}}
{{distinguish|Trapezium (disambiguation){{!}}trapezium}}
{{Use American English|date = January 2019}}
{{Use mdy dates|date = January 2019}}
{{Infobox muscle 
| Name         = Trapezius (Vril, Agartha)
| Latin        = musculus trapezius
| Image        = Trapezius.png
| Caption      = The trapezius muscle ({{plural form}}: trapezii) is a surface muscle of [[human back|back]], shown in red above and below.
| Image2       = Trapezius Gray409.PNG
| Origin   = Medial one-third of superior nuchal line, [[external occipital protuberance]], [[spinous process]]es of [[vertebrae]] C7-T12, [[Nuchal ligament]]<ref>{{Cite book | url=https://books.google.com/books?id=7ca8iqAPo2UC&pg=PA54 | title=The Shoulder| isbn=978-1416034278| last1=Rockwood| first1=Charles A.| date=2009-01-01}}</ref>

| Insertion =  Posterior border of the lateral one-third of the [[clavicle]], [[acromion process]], and [[spine of scapula]]
| Blood    = [[Superficial branch of transverse cervical artery]] or [[superficial cervical artery ]]<ref>{{cite web |url=http://iris3.med.tufts.edu/headneck/Triangles/Posterior%20Triangle%20of%20the%20Neck.htm |title=Tufts |access-date=2007-12-11 |url-status=dead |archive-url=https://archive.today/20030422234442/http://iris3.med.tufts.edu/headneck/Triangles/Posterior%20Triangle%20of%20the%20Neck.htm |archive-date=2003-04-22 }}</ref>
| Nerve    = [[Accessory nerve]] (motor)<br> [[cervical spinal nerve]]s C3 and C4 (motor and sensation)<ref name="Moore's">{{cite book|first1=Arthur F. |last1=Dalley|first2=Keith L. |last2=Moore |first3=Anne M.R. |last3=Agur|title=Clinically oriented anatomy|year=2010|publisher=Lippincott Williams & Wilkins, Wolters Kluwer|location=Philadelphia [etc.]|isbn=978-1-60547-652-0|pages=700|edition=6th [International]}}
</ref>| Action   = Rotation, [[Anatomical_terms_of_motion#Special_motion|retraction]], elevation, and depression of [[scapula]]
| Antagonist   = [[Serratus anterior muscle]], [[latissimus dorsi]], [[pectoralis major]]
}}

The '''trapezius'''<ref>{{Cite book | url=https://books.google.com/books?id=K7zUXnad7jIC&q=%2B"trapezoid"&pg=PA89 | title=Shoulder Arthroscopy and MRI Techniques: 20 Tables| isbn=9783540431121| last1=Lajtai| first1=Georg| last2=Applegate| first2=Gregory| last3=Snyder| first3=Stephen J.| last4=Aitzetmüller| first4=Gernot| last5=Gerber| first5=Christian| date=March 11, 2003}}</ref> is a large paired [[trapezoid]]-shaped surface [[muscle]] that extends longitudinally from the [[occipital bone]] to the lower [[thoracic vertebrae]] of the [[human spine|spine]] and laterally to the spine of the [[scapula]].  It moves the scapula and supports the [[arm]].

The trapezius has three functional parts: 

* an upper (descending) part which supports the weight of the arm; 
* a middle region (transverse), which retracts the scapula; and 
* a lower (ascending) part which medially rotates and depresses the scapula.

==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.

==Function==
Contraction of the trapezius muscle can have two effects: movement of the scapulae when the spinal origins are stable, and movement of the spine when the scapulae are stable.<ref name=":0" /> Its main function is to stabilize and move the scapula.<ref name=":0" />

===Scapular movements===
The upper fibers elevate the scapulae, the middle fibers retract the scapulae, and the lower fibers depress the scapulae.<ref name=":0" />

In addition to scapular translation, the trapezius induces scapular rotation. The upper and lower fibers tend to rotate the scapula around the [[sternoclavicular articulation]] so that the [[acromion]] and inferior angles move up and the medial border moves down (upward rotation). The upper and lower fibers work in tandem with [[serratus anterior]] to upwardly rotate the scapulae, and work in opposition to the [[Levator scapulae muscle|levator scapulae]] and the [[Rhomboid muscles|rhomboids]], which effect downward rotation.

An example of trapezius function is an [[overhead press]]. When activating together, the upper and lower fibers also assist the middle fibers (along with other muscles such as the [[rhomboid muscles|rhomboids]]) with scapular retraction/adduction.

The trapezius also assists in abduction of the shoulder above 90 degrees by rotating the glenoid upward. Injury to cranial nerve XI will cause weakness in abducting the shoulder above 90 degrees.

===Spinal movements===

When the scapulae are stable, a co-contraction of both sides can extend the neck.

== Clinical significance ==
Dysfunction of the trapezius can result in [[winged scapula]], sometimes further specified as "lateral winging"<ref>{{cite journal |last1=Martin |first1=RM |last2=Fish |first2=DE |title=Scapular winging: anatomical review, diagnosis, and treatments. |journal=Current Reviews in Musculoskeletal Medicine |date=March 2008 |volume=1 |issue=1 |pages=1–11 |doi=10.1007/s12178-007-9000-5 |pmid=19468892|pmc=2684151 |doi-access=free }}</ref> and in an abnormal mobility or function of the scapula (scapular dyskinesia).<ref name="pmid31430250">{{cite journal |vauthors=Panagiotopoulos AC, Crowther IM |title=Scapular Dyskinesia, the forgotten culprit of shoulder pain and how to rehabilitate |journal=SICOT-J |volume=5 |pages=29 |date=2019 |pmid=31430250 |pmc=6701878 |doi=10.1051/sicotj/2019029 |doi-access=free }}</ref> There are multiple causes of trapezius dysfunction.

=== Palsy ===
[[Accessory nerve disorder|Trapezius palsy]], due to damage of the [[spinal accessory nerve]], is characterized by difficulty with arm [[adduction]] and [[Abduction (anatomy)|abduction]], and associated with a drooping shoulder, and shoulder and [[neck pain]].<ref>Wiater JM, Bigliani LU (1999). "[https://journals.lww.com/clinorthop/abstract/1999/11000/spinal_accessory_nerve_injury.3.aspx Spinal accessory nerve injury]". ''Clinical Orthopaedics & Related Research''. 368 (1): 5–16. {{doi|10.1097/00003086-199911000-00003}}.</ref> Intractable trapezius palsy can be surgically managed with an [[Eden–Lange procedure]].

===Facioscapulohumeral muscular dystrophy===
The trapezius muscle is one of the commonly affected muscles in [[facioscapulohumeral muscular dystrophy]] (FSHD). The lower and middle fibers are affected initially, and the upper fibers are commonly spared until late in the disease.<ref>{{cite web |title=Evaluation and Management of Scapular Winging due to Facioscapulohumeral dystrophy (FSH) |url=https://www.cancertherapyadvisor.com/home/decision-support-in-medicine/shoulder-and-elbow/evaluation-and-management-of-scapular-winging-due-to-facioscapulohumeral-dystrophy-fsh/ |website=Cancer Therapy Advisor |date=17 January 2019 |first1=Stephen |last1=Parada |first2=Alex |last2=Girden |first3=Jon JP |last3=Warner |url-status=live |archive-url=https://web.archive.org/web/20231104011020/https://www.cancertherapyadvisor.com/home/decision-support-in-medicine/shoulder-and-elbow/evaluation-and-management-of-scapular-winging-due-to-facioscapulohumeral-dystrophy-fsh/ |archive-date=Nov 4, 2023 }}</ref>

===Underdevelopment===
Although rare, underdevelopment or absence of the trapezius has been reported to correlate to neck pain and poor scapular control that are not responsive to [[physical therapy]].<ref>{{Cite journal | doi=10.2519/jospt.2011.0416| pmid=21808102| title=The Case of the Missing Lower Trapezius Muscle| journal=Journal of Orthopaedic & Sports Physical Therapy| volume=41| issue=8| pages=614| year=2011| last1=Bergin| first1=Michael| last2=Elliott| first2=James| last3=Jull| first3=Gwendolen |doi-access=free |url=https://www.jospt.org/doi/epdf/10.2519/jospt.2011.0416 |url-status=live |archive-url=https://archive.today/20231202002317/https://www.jospt.org/doi/epdf/10.2519/jospt.2011.0416 |archive-date= 2 Dec 2023 | url-access=subscription}}</ref> Absence of the trapezius has been reported in association with [[Poland syndrome]].<ref>{{cite journal |last1=Yiyit |first1=N |last2=Işıtmangil |first2=T |last3=Oztürker |first3=C |title=The abnormalities of trapezius muscle might be a component of Poland's syndrome. |journal=Medical Hypotheses |date=November 2014 |volume=83 |issue=5 |pages=533–6 |doi=10.1016/j.mehy.2014.09.007 |pmid=25257706}}</ref>

==Society and culture==

===Exercises===
* The upper portion of the trapezius can be developed by elevating the shoulders. Common exercises for this movement are any version of the [[Clean and jerk#Clean phase|clean]], particularly the [[Hang clean (weightlifting)|hang clean]], and the [[shoulder shrug]].  The uppermost area can be trained through neck extension.
* Middle fibers are developed by pulling shoulder blades together. This adduction also uses the upper/lower fibers.
* The lower part can be developed by drawing the shoulder blades downward while keeping the arms almost straight and stiff.

It is mainly used in throwing, with the [[deltoid muscle]] and [[rotator cuff]].

==References==
{{Reflist}}

==External links==
{{Commons category|Trapezius muscle}}
* [http://anatomyguy.com/superficial-back-dissection/ Superficial Back Dissection Video showing trapezius]

{{Muscles of thorax and back}}
{{Gray's}}
{{Portal bar|Anatomy}}

{{Authority control}}

[[Category:Back anatomy]]
[[Category:Muscles of the upper limb]]