TRAPEZIUS MUSCLE: CHARACTERISTICS, FUNCTIONS, SYNDROMES, DISORDERS - ANATOMY AND PHYSIOLOGY - 2025

The trapezius is a large, flat, superficial muscle located on the back of the neck and rib cage. The name of the trapezius muscle comes from the Latin musculus trapezius. It is triangular in shape and its fibers are divided into three parts, upper descending, middle and lower ascending.

Each section participates in a different movement. If you look at both trapezoids from behind, you can see that between the two they form the configuration of a diamond.

Mikael Häggström.When using this image in external works, it may be cited as: Häggström, Mikael (2014). "Medical gallery of Mikael Häggström 2014". WikiJournal of Medicine 1 (2). Graphic representation of the trapezius muscle. Source: DOI: 10.15347 / wjm / 2014.008. ISSN 2002-4436. Public Domain.orBy Mikael Häggström, used with permission.. Edited image.

The muscle originates from the occipital scale and the first spinous processes of the cervical and thoracic vertebrae, with insertion points on the scapula, the acromion, and the clavicle.

According to the insertion sites that this muscle has, it contributes to maintaining the balance of the shoulder girdle and the cervical spine. It is innervated by the accessory nerve, branches of the second, third, and fourth cervical nerves, as well as the trapezius nerve.

characteristics

The trapezius is a flat and superficial muscle, in fact it is the most superficial of all the muscles in the area. It is a pair muscle, that is, there is a left and a right trapezius, located symmetrically.

Faces

This muscle is located between the neck and the back, and is triangular in shape. Two faces are distinguished: a superficial and a deep one.

The superficial one covers the back of the trunk in its upper part. The deep face covers the following muscles: the levator scapulae muscle, the splenium, the semispinatus of the head, the spinous, the longis, the iliocostalis and the beginning of the latissimus dorsi muscle.

While, laterally and deeply, it borders the suprascapular region, supraspinatus fossa and superior and medial portion of the infraspinatus region.

Borders

Three borders can also be distinguished: anterior, medial and inferior.

The anterior border is quite thick and covers the upper and posterior part of the clavicle. This edge is important for shaping the shoulder, as it helps to lift the integuments in the area. The medial border is the meeting point with its counterpart, located on the opposite side.

Surgery and other uses

Because it is a large muscle, it has been used successfully for muscle reconstruction surgeries in defects at the neck and head. The technique is called the vertical trapezius muscle-skin flap.

Mayer's technique has also been used to transfer the trapezius to the humerus, especially in patients with shoulder palsy due to brachial plexus injury.

Origin

The fibers of this muscle come from the occipital scale, the ligament of the neck and the spinous processes of the cervical and thoracic vertebrae, specifically from the C7 to T12 vertebra.

The upper fibers originate from the upper and medial part of the nape (nuchal ligament).

Meanwhile, the middle fibers leave the spinous processes of the C7 to T3 vertebrae, linked to their respective interspinous ligaments.

Whereas, the origin of the inferior fibers continues in the following spinous processes and interspinous ligaments, that is, from the T4 to T12 vertebrae.

Insertion

The muscular fascicles are directed towards three structures that are: the spine of the scapula, the acromion and the clavicle.

The muscle fibers of the upper part of the trapezius are arranged in a descending and oblique direction, and are attached to the posterior and superior border of the clavicle.

For their part, the fibers of the middle portion are arranged transversely and insert into the acromion and the upper lip of the spine of the shoulder blade.

Meanwhile, the fibers of the lower portion form a triangle with their fascicles arranged ascending, and cover the medial portion of the spine of the scapula.

Innervation

It is innervated by the external branch of the accessory cranial nerve or also called the accessory spinal nerve. This nerve supplies the trapezius and also the sternocleidomastoid muscle.

The accessory nerve corresponds to the XI cranial nerve. Its function is purely motor and damage to this nerve will cause severe limitation to shrug the shoulders and difficulty in moving the head.

The trapezius muscle also receives innervation from the cervical plexus in its upper part, specifically it welcomes posterior branches of the cervical nerves (C2, C3 and C4), which anastomoses with the accessory nerve. The latter have a sensitive and proprioceptive function.

Whereas, it is deeply innervated by the nerve that bears its name "trapezius nerve." The trapezius nerve is a terminal branch of the accessory nerve, which inserts deep into the lower part of the muscle.

Irrigation

The superficial descending branch of the transverse cervical artery supplies the medial and lateral trapezius. Whereas, the deep branch of the same artery (dorsal artery of the scapula) also supplies the trapezius.

Likewise, it receives a small blood supply from the collateral branch of the suprascapular artery and from the dorsal branch of the posterior intercostal arteries (first branch).

Features

The bilateral function of the trapezius muscles is to stretch the vertebral column at the cervical and thoracic level. Both muscles are agonists.

However, muscle function can be studied according to its divisions and characteristics of its fibers. In this sense, it can be said that the contraction of the upper, middle and lower part of the muscle produce different movements.

Superior fibers

The superior fibers elevate the clavicle and indirectly also produce the elevation of the scapula, an action that occurs when the clavicle is turned over the sternoclavicular joint. It also allows the head to be moved on the same side of the muscle and rotated to the opposite side.

On the other hand, the superior fibers participate in the upward rotation of the glenoid cavity, complementing the function of the serratus anterior and the levator scapulae.

It should be noted that in the ascending rotation of the glenoid cavity the middle and inferior fibers also collaborate. These support the deltoid tuber during this action.

Medium fibers

The middle fibers participate in the elevation of the scapula together with the superior fibers, being the most active during the adduction movement (scapular movement in a medial direction), although in reality this movement activates the entire muscle in general.

The middle fibers, together with the lower fibers, serve as stabilizers of the position of the scapula, while the upper fibers, together with other muscles, rotate the glenoid fossa upward.

Lower fibers

For their part, the inferior fibers participate in the scapular depression and in the downward rotation of the glenoid cavity.

Upper, intermediate and lower fibers of the trapezius muscle. Source: Anatomography. Edited image.

Syndromes

Myofascial trigger points

The trapezius is frequently the target of contractures that produce myofascial trigger points. These are often the cause of transient or cervicogenic headaches.

Trigger points can be caused by trauma or weight or pressure overload.

Example of trauma: whiplash syndrome after a car accident.

Example of overload: carrying extremely heavy bags slung over your shoulder.

The trigger points of the upper part of the trapezius can radiate the pain upwards, that is, towards the neck, and can reach the mastoid process, causing tension neck pain (neck pain).

If other muscles such as the splenium or the levator scapulae are affected, a stiff neck can occur. In severe cases, the pain can radiate down the jaw, lower molars, and up to the temple.

Patients with trigger points in the middle of the muscle report superficial burning at the level of processes C7 to T3 and, occasionally, have chills with piloerection (goose bumps) in the lateral area of ​​the arm.

Pain towards the shoulder is also frequent, especially at the acromion level. Trigger points are caused by keeping your arms raised for a long time.

Trigger points in the lower area of ​​the muscle produce pain at various levels: suprascapular area, interscapular area, acromial area and cervical area. Its presence does not significantly affect the movement of the neck.

Tendinopathies

Muscle tendon involvement and inflammation. Example: torticollis (impediment to rotate the neck), which is produced by the tear of the muscle or its ligaments.

References

1. Simons D, Travell J, Simons L. (2007). Pain and myosfacial dysfunction, the trigger point manual. Volume 1. 2nd edition, Editorial Panamericana. Spain. Available at: books.google.
2. "Trapezius muscle" Wikipedia, The Free Encyclopedia. 15 Aug 2019, 03:45 UTC. 15 Sep 2019, 04:56 en.wikipedia.org
3. Saldaña E. (2015). Manual of human anatomy. Available at: oncouasd.files.wordpress
4. Gallego-Gónima S, Herrera-Montoya J, Ruiz-Cuervo A, Cárdenas-Castellanos Y. Clinical experience with the vertical muscle-cutaneous trapezius flap in head and neck reconstruction. Cir. plast. iberolatinoam. 2014; 40 (1): 63-72. Available in: scielo
5. Monreal-González R, Díaz-Ramos H, León-Santana P, Paredes-González L. Trapezius transfer in brachial plexus paralysis. Rev Cubana Ortop Traumatol. 2007; 21 (1). Available in: scielo