The trapezius is a large, broad muscle on the back. It’s really more like three muscles as it can be divided into sections based on fiber direction and main actions. It’s typically divided into an upper, middle, and lower section. Trapezius is an important muscle to know as it can be relevant to one of the activities we all spend a lot of time doing: sitting in front of the computer! The common posture for computer users can shorten the upper trapezius and cause headaches and other symptoms.

Where is the trapezius muscle located?

Trapezius is a large muscle with many places of attachment. Sections of the trapezius muscle can even work in opposition to each other. To understand how that can happen, we need to see where trapezius attaches, so let’s take a look at the specific attachments for each section of the trapezius muscle.

What is the origin of the trapezius?

The upper section of trapezius originates on the base of the occiput, the ligamentum nuchae, and the spinous processes of vertebrae C1-C7.

The middle section of trapezius originates on the spinous processes of vertebrae C7-T3.

The lower section of trapezius originates on the spinous processes of vertebrae T4-T12.

What is the insertion of the trapezius?

The upper section of trapezius inserts on the lateral clavicle and the acromion process.

The middle section of trapezius inserts on the spine of the scapula.

The lower section of trapezius inserts on the root of the spine of the scapula.

What actions does the trapezius muscle do?

All three sections of the trapezius muscle contribute to upward rotation of the scapula. They can also help stabilize the scapula.

Each of the three sections of trapezius also contributes to another movement that the other sections of the muscle don’t do. The sections of trapezius can function independently of one another.

The upper section of trapezius elevates the scapula. It can also laterally flex the head to the same side if the shoulder is held in place.

The middle section of trapezius retracts or adducts the scapula.

The lower section of trapezius depresses the scapula.