Trapezius muscle

Dr Craig Hacking et al.

The trapezius muscle is a large, broad superficial muscle of the posterior neck and back. It gains its name from its diamond shape. Along with sternocleidomastoid muscle, it is invested by the superficial layer of the deep cervical fascia, which splits around it. 

  • origin: superior nuchal line, inion, nuchal ligament and spinous processes of C7-T12 vertebrae 
  • insertion: clavicle and scapula
  • innervation: accessory nerve (CN XI)
  • action: complex movements of the scapula and neck
Origin 

It has many origins due to its large size:

  • medial third of superior nuchal line
  • inion and external occipital protuberance
  • nuchal ligament
  • spinous processes of C7-T12 vertebrae and the corresponding supraspinous ligaments
Insertion
  • clavicle: lateral third
  • scapula: acromion and spine 
Relations
  • all fibres: retract the scapula medially
  • upper fibres only: elevate and rotate scapula up to aid in shoulder abduction
  • middle fibres only: retract scapula
  • lower fibres only: depress and rotate scapula down
  • upper and lower fibres together: rotate spinous process of scapula superiorly
  • with the shoulders fixed:
    • bilateral contraction extends neck
    • unilateral contraction produces ipsilateral flexion
Upper limb anatomy
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Article information

rID: 41023
Section: Anatomy
Tag: refs
Synonyms or Alternate Spellings:

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