Trapezius Muscle Anatomy aka "The Traps"
Anatomy of the Upper Back Muscles

The trapezius muscle is also known as the "Traps" muscle. This page has a brief discussion of the trapezius anatomy.

The Trapezius is a broad kite shaped muscle that runs from the base of the head down the tips of the vertebrae. The Trapezius is one muscle, but it has 3 distinct parts: upper, middle, and lower.

Origination/ Starting Postion:

The origin of the trapezius is the base of the skull at the medial third of the superior nuchal line and the external occipital protuberance.

It also originates from the ligamentum nuchae(a thick ligament that goes over the tips of the cervical vertebrae) and the spinous processes of the thoracic vertebrae.

Insertion/ Ending Position:

The upprer traps inserts on the lateral thrid of the clavicle. the middle traps inserts on the acromion process (outer top portion) of the scapula, and the lower traps inserts on the spine of the scapula.

Actions:

The upper traps work to elevate the scapula (shrug the shoulders upwards).

The middle fibers of the traps retract the shoulder blades (pull the shoulder blades back and together).

The lower fibers of the traps depress the scapula.

A special motion of the trapezius is upwards rotation. When the upper traps and the lower traps work together, they will turn the scapula upwards.

Upward rotation is especially important during over head activities.

Nerve Supply:

The trapezius is innervated partially by Cranial Nerve XI, which is the Spinal Accessory Nerve, and the traps are also innervated by the nerve roots of C3 and C4.

Exercises for the Trapezius Muscle

The trapezius will work during every arm exercise. It will either move the scapula or stabilize the scapula.

The upper trapezius will work really hard during exercises like barbell shrugs.

The middle traps work with the rhomboids to pull the shoulder blades back together during exercises like seated rows or reverse shoulder flyes.

The middle traps will also work during exercises like pull ups and the lat pull down machine.

The lower traps will work to pull the shoulder blade downwards on exercises like pull ups or the lat pull down.

During chest exercises the trapezius as a whole will help to stabilize the scapula, and during shoulder exercises, like lateral raises or the military press, the trapezius will work to rotate the scapula upwards.

It's okay to work the trapezius in isolation, with various types of shrugs or pinching motions for the shoulder blades, and a strong trapezius means a more stable shoulder joint.

Mix up your exercises and don't forget to work your traps.

Yours in health,
Dr. Charles PT/PT

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