Proximal attachments: External Occipital Protuberance, Nuchal Ligament, Spinous Process, and Supraspinous ligament of T1-T12

Distal attachment: Scapular Spine, Acromion, and lateral 3rd of the Clavicle

Actions:

The trapezius is a major mover of the scapula, it can perform scapular elevation, upward rotation, retraction and depression. It can assist in extension and lateral flexion of the head and neck. 

Some modern-day examples of the action of the trapezius include shrugging up and down and the movement of the scapula when you go to reach overhead.

Unique Features:

The trapezius is such a large fan-shaped muscle that most sources separate it into three regions that can act individually:

• Upper Fibers: Attaching from the skull and nuchal ligament down and out to the lateral clavicle and acromion of the scapula. This region is responsible for upward rotation, elevation, extension, and lateral flexion of the head and neck
• Middle Fibers: Attaching from C7-T1 Spinous processes out to the spine of the scapula. This region is responsible for the retraction of the scapula
• Lower Fibers: Attaching from T4-T12 Spinous processes out the lower portion of the scapular spine. This area produces Scapular Depression and Upward rotation

The trapezius is a common complaint site due to its tendency to be overworked in our modern lifestyle of sitting, phone scrolling, and computer work. Symptoms include shoulder and neck discomfort, headaches, and excessive hypertonicity in the upper and middle fibers paired with underdeveloped and weak lower fibers.

Trigger Point and Pain Referral Patterns:

The pain referral pattern is relatively local to the trapezius but sometimes can lead to discomfort up towards the temples and into the temporalis muscle.

Images sources from Biodigitalhuman @ human.biodigital.com