[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) › Upper trapezius [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) # Upper trapezius The upper trapezius runs from the neck to the top of the shoulder; it shrugs the shoulder and helps rotate the shoulder blade upward. Official name: Trapezius, upper (descending) part [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=upper_limb&select=trapezius_upper&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The upper part of the large diamond-shaped muscle of the upper back and neck. ## What it does Shrugs the shoulder and helps rotate the shoulder blade upward. ## Key points - Its front edge is the back border of the posterior triangle of the neck; the accessory nerve (CN XI) crosses that triangle just under the skin and fascia to reach its deep surface - Resisted shoulder shrug is the bedside test of CN XI for this part; the sternocleidomastoid, the nerve's other muscle, is tested by turning the head against resistance - Starts the upward rotation of the [scapula](https://durgical.com/en/anatomy/scapula/) together with the [lower trapezius](https://durgical.com/en/anatomy/trapezius-lower-part/) and the [serratus anterior](https://durgical.com/en/anatomy/serratus-anterior/), the force couple that lets the arm go overhead ## Key facts **Origin** External occipital protuberance, superior nuchal line, [nuchal ligament](https://durgical.com/en/anatomy/nuchal-ligament/) **Insertion** Lateral third of the clavicle **Action** Elevates and upwardly rotates the scapula; extends and side-bends the neck **Nerve** Accessory nerve (CN XI); C3–C4 (proprioception) **Blood supply** Transverse cervical artery, [occipital artery](https://durgical.com/en/anatomy/occipital-artery/) ## Relations **Superficial** [Skin](https://durgical.com/en/anatomy/skin/) of the nape and top of the shoulder; the investing layer of deep [cervical fascia](https://durgical.com/en/anatomy/superficial-investing-cervical-fascia/) splits to enclose it **Deep** [Splenius](https://durgical.com/en/anatomy/splenius-capitis-muscle/) capitis, [semispinalis](https://durgical.com/en/anatomy/semispinalis-muscles/) capitis and [levator scapulae](https://durgical.com/en/anatomy/levator-scapulae/); the [accessory nerve](https://durgical.com/en/anatomy/accessory-nerve/) and the superficial branch of the transverse cervical artery run on its deep surface **In front** The posterior triangle of the neck, with the [sternocleidomastoid](https://durgical.com/en/anatomy/sternocleidomastoid-muscle/) as its front border; the triangle holds CN XI, the trunks of the [brachial plexus](https://durgical.com/en/anatomy/roots-of-brachial-plexus/) and the lymph nodes of the posterior neck **Below** The lateral third of the [clavicle](https://durgical.com/en/anatomy/clavicle/), where it inserts opposite the origin of the [front deltoid](https://durgical.com/en/anatomy/deltoid-anterior-part/); below the C7 level it continues as the [middle trapezius](https://durgical.com/en/anatomy/trapezius-middle-part/) ## How to find it With the person seated and the examiner behind, a shrug against downward pressure on both shoulders makes it stand out as the sloping ridge from the [base of the skull](https://durgical.com/en/anatomy/occipital-bone/) to the outer end of the clavicle. Comparing both sides shows a droop or loss of bulk. ## Examination - Resisted shrug: weakness or a lower, flatter shoulder on one side points to an accessory nerve (CN XI) lesion; normal head turning with a weak shrug places the lesion below the branch to the sternocleidomastoid, as in the posterior triangle ## On imaging Ultrasound and MRI show it as a thin sheet over the back of the neck and shoulder. After accessory nerve injury, often from surgery or a biopsy in the posterior triangle, CT or MRI shows the muscle thin and fatty compared with the other side. Ultrasound can follow the nerve in the posterior triangle; electromyography confirms denervation. ## Clinical notes - The accessory nerve can be cut during a lymph node biopsy or a neck dissection in the posterior triangle: the shoulder droops and aches, the arm cannot be raised fully to the side and the scapula wings laterally - Neck dissections that spare CN XI were developed to avoid this painful 'shoulder syndrome' - Scapular dyskinesis often shows an overactive upper trapezius (the shoulder hikes up as the arm rises) with weak lower trapezius and serratus anterior ## Anatomical variants - Rare: absence or underdevelopment of part of the muscle, and accessory slips ## Development The [trapezius](https://durgical.com/en/anatomy/trapezius-muscle/) and sternocleidomastoid grow from one premuscle mass in the occipital region, just behind the last pharyngeal arch; the accessory nerve enters it early and is carried down as the mass spreads to the shoulder girdle and [spine](https://durgical.com/en/anatomy/region/spine/). ## Related conditions - [Tension-type headache](https://durgical.com/en/conditions/tension-type-headache/) - [Acromioclavicular joint separation](https://durgical.com/en/conditions/acromioclavicular-joint-separation/) - [Winged scapula](https://durgical.com/en/conditions/winged-scapula/) ## Test yourself Think of the answer, then tap the question to see it. ## What nerve supplies the upper trapezius, and how is it tested at the bedside? The accessory nerve (CN XI); by a resisted shoulder shrug. ## Why is the accessory nerve at risk in the posterior triangle of the neck? It crosses the triangle just under the skin and fascia to reach the upper trapezius; a lymph node biopsy or neck dissection can cut it. ## A patient has a weak shrug but normal head turning against resistance. Where is the accessory nerve lesion? Below the branch to the sternocleidomastoid, as in the posterior triangle of the neck. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/descending-part-of-trapezius-muscle/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** pars descendens musculi trapezii TA2 2227 **Official Spanish (DeCS)** Porción descendente del músculo trapecio **English (TA2)** Trapezius, upper (descending) part ## Related - [Clavicle](https://durgical.com/en/anatomy/clavicle/) Sources: Terminologia Anatomica (TA2); [Anatomy, Back, Trapezius](https://www.ncbi.nlm.nih.gov/books/NBK518994/); Anatomy of the Human Body (20th ed.): Development of the Muscles (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain. ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/descending-part-of-trapezius-muscle/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/descending-part-of-trapezius-muscle/