Trapezius Muscle Anatomy and Function

A Long Triangular Muscle Located in the Upper Back

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The trapezius is a large muscle in your back. It starts at the back of your head and neck, extends across your shoulders, and down the middle of your back, forming a trapezoid.

Also known as traps, the trapezius muscles play an important role in posture. They move the shoulders, lift arms out to the side, and protect the neck and spine. You use them when you shrug or pull your shoulders back.

This article explains the anatomy and function of the trapezius muscles. It also discusses conditions that affect the trapezius and how they are treated.


The trapezius muscle is divided into 3 areas:

  1. Upper trapezius
  2. Middle trapezius
  3. Lower trapezius

Each area has a different use. The upper trapezius arises from your occipital bone in the back of your skull and the nuchal line in the back of your neck. The muscle also has attachments to the spinous processes of cervical level one through six via the ligamentum nuchae. Attachments of the lower fibers of the trapezius arise from the spinous processes of cervical seven through thoracic level 12.

The muscular fibers of the triangular-shaped traps travel to insert on the spine of the scapula and the acromion of the scapula. They also attach to the outer one-third of the clavicle or collar bone.

Nerve innervation to the trapezius muscle is interesting, as it is served by a cranial nerve. This nerve called the spinal accessory nerve, or cranial nerve XI, arises from your brain stem and travels from your skull down to the trapezius muscle, providing motor input.

Physiotherapist, chiropractor putting on pink kinesio tape on woman patient. Pink: cervical, trapezius, supraspinatus, blue: high dorsal paravertebral
Sunlight19 / Getty Images


The trapezius muscle acts as both a posture stabilizer and a movement muscle.

Common actions you may recognize in which the trapezius is involved include shrugging your shoulders, tilting, turning and extending your neck and keeping your shoulder blades down your back.

Upper Trapezius

The upper trapezius, the part that goes across the tops of your shoulders, can elevate or bring up your shoulder girdle. It also helps extend, tilt, and rotate your neck, which has the effect of bringing your head back, to the side, and turning it. The rotation function takes the head into the opposite side to which this neck and shoulder muscle is located.

While the elevation of the shoulders is the official action of the upper trapezius muscle, this is not always a good thing. If you work at a desk, or your job involves a lot of driving, you likely know this firsthand.

When the shoulder girdle is pulled up in a constant and chronic way, it leads to misalignment that can make the upper traps chronically tight. The result may well be a pain, limited movement and a loss of neck flexibility.

Together with the lower traps, the upper trapezius also helps rotate your shoulder blade upward. This movement occurs when you lift your arm up to the side, providing your shoulders, neck, and upper back are in good alignment and your muscles are flexible.

Middle Trapezius

The middle trapezius helps bring the shoulder blades back, toward the spine. Again, if you sit at a desk or drive all day, this may prove a handy move for preventing or managing excessive kyphotic posture in that area. The middle trapezius also helps stabilize the shoulder during certain arm movements. 

Lower Trapezius

And finally, the lower trapezius muscle is tasked with the upper and mid-spine stabilizing action of bringing the shoulder girdle down. This is the opposite action to that of the upper trapezius. 

The trapezius is an accessory breathing muscle. This means that it helps open up a small amount of breathing room in the upper chest area. 

But instead of relying on this muscle for breath support, consider developing the capacity of your most primary and powerful breathing muscle—the diaphragm.

Associated Conditions

Problems with the trapezius are rare but may occur. Any injury to the spinal accessory nerve (cranial nerve XI) can cause weakness or paralysis of the trapezius muscle.

This would cause you difficulty in shrugging your shoulder or lifting your arm up properly. Your shoulder may also sag down on one side.

Muscle spasms and pain may also affect the traps. For all but the most vigilant of us, living and working in the 21st century can bring about a serious deficit in movement. While this has its conveniences, you should be aware of the drawbacks.

For one, muscles that remain inactive for most of the day are much more likely to go into spasm and give you pain. And the trapezius muscles may be just the muscles that do this. You can check this for yourself using simple observation.

Ask Yourself

  • How well can I move my shoulders up, and especially, down?
  • Do I have pain or uncomfortable sensations at the top of either shoulder or both? 

If your shoulder movement is limited and/or there's a pain in the area, one or both of your upper trapezius muscles may be in spasm. Fortunately, solutions exist that for the most part are non-medical and easy to implement.


Tight upper trapezius muscles often respond well to massage therapy. And because they are located such that you can reach your own, you might consider trying a self-massage technique.

The upper trapezius muscle, along with other shoulder muscles, such as the infraspinatus, tends to be fertile ground for the development of painful myofascial trigger points. A massage therapist skilled in the art of myofascial release may be able to help you though.

Also, a 2018 study published in the Journal of Sports Rehabilitation suggests that dry needling, a form of acupuncture, may also help alleviate the pain and related symptoms perpetuated by trigger points.

A Word From Verywell

Exercises for the trapezius can help them perform their job appropriately. Things like shoulder shrugs and scapular stabilization exercises may be done to keep your traps working properly. Checking in with your healthcare provider or physical therapist before starting trapezius exercises is recommended.

Frequently Asked Questions

  • Are there trapezius muscle exercises?

    Yes, basic exercises like push-ups, pull-ups, and shrugs strengthen the trapezius muscle. Also, self-massage techniques can be performed to relax the trapezius muscle if it feels tight. Be sure to read up on proper technique when performing any exercise.

  • What is trapezius muscle strain?

    When the trapezius muscle is stretched too far, this is known as trapezius muscle strain. In some cases, the muscle can tear. Most minor strains and tears will heal with time and rest, but if the tear is severe, the muscle may require surgery to effectively heal.

  • What is trapezius innervation?

    Innervation is the supply of nerves to a body part. In the case of the trapezius muscle, it is innervated by the spinal accessory nerve, or cranial nerve XI. This nerve extends from the skull to the trapezius muscle and controls the muscle's movement.

  • How do you relieve trapezius pain?

    Mild trapezius pain can often be resolved using ice, moist heat, over-the-counter pain relievers, and stretching. Ongoing trapezius pain typically responds well to massage therapy or acupuncture. Physical therapy can also help ease trapezius pain.

  • How do you loosen a tight trapezius muscle?

    Tight trapezius muscles can be loosened with stretching, massage, and dry-needling.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Ourieff J, Agarwal A. Anatomy, Back, Trapezius. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.

  2. Terson de paleville DG, Mckay WB, Folz RJ, Ovechkin AV. Respiratory motor control disrupted by spinal cord injury: mechanisms, evaluation, and restoration. Transl Stroke Res. 2011;2(4):463-73. doi:10.1007/s12975-011-0114-0

  3. Kamali F, Sinaei E, Morovati M. Comparison of Upper Trapezius and Infraspinatus Myofascial Trigger Point Therapy by Dry Needling in Overhead Athletes With Unilateral Shoulder Impingement Syndrome. J Sport Rehabil. 2019;28(3):243-249. doi:10.1123/jsr.2017-0207

  4. Cleveland Clinic. Trapezius muscle.

  5. Ourieff J, Scheckel B, Agarwal A. Anatomy, back, trapezius. StatPearls.

Additional Reading

By Anne Asher, CPT
Anne Asher, ACE-certified personal trainer, health coach, and orthopedic exercise specialist, is a back and neck pain expert.