The Trapezius is part of the group of muscles which elevate and retract the shoulder girdle. It is divided into parts; upper, middle and lower.

Part 1: Upper fibres of the cervical vertebrae. This is the weakest part of the muscle and only provides minor elevation of the clavicle

  • Part 2: The area commonly known as upper trapz. This is a strong elevator, rotator and retractor of the scapula
  • Part 3: The mid-portion of the Trapzius. These fibers are mainly responsible for scapula retraction
  • Part 4: The lower fibers of Trapezius. This part of the muscle assists in retraction and rotation.

When all parts of the muscle work together they have the effect of simultaneously elevating and retracting the scapula. The Trapezius is used most commonly to fix the scapula to allow the Deltoid to move the Humerus.

Origin

  • Base of skull
  • Ligaments cervical (upper) spine
  • Spinous processes of Cervical 7 to Thoracic 12 vertebrae

Insertion

  • Posterior outer 1/3 of the clavicle
  • Acromion process
  • Spine of the scapula

Actions

  • Elevate the Scapula
  • Retract the Scapula
  • Upward rotation of the scapula

Which nerve supplies the muscle?

  • Cranial nerve

Daily uses

  • Shrugging the shoulders
  • Overhead movements or the arm

Shoulder Girdle Muscles:

More Human Muscles: