Trapezius

The trapezius is a large superficial muscle which extends longitudinally from the occipital bone to the lower thoracic vertebrae, and laterally to the spine of the shoulder blade.

Anatomy of the Trapezius

The trapezius muscle is divided into 3 areas:

• Upper trapezius - supports the weight of the upper limb,
• Middle trapezius - retracts the scapulae, and
• Lower trapezius - medially rotates and depresses the scapulae.

The trapezius is innervated by the accessory nerve and the ventral rami of third and fourth cervical spinal nerves, which also supplies the sternocleidomastoid muscle.

It arises from the external occipital protuberance and the medial third of the superior nuchal line of the occipital bone, from the ligamentum nuchae, the spinous process of the seventh cervical, and the spinous processes of all the thoracic vertebrae, and from the corresponding portion of the supraspinal ligament.

From this origin:

The upper trapezius fibres proceed downward and laterally. They are inserted into the posterior border of the lateral third of the clavicle.

The lower trapezius fibres proceed upward and lateral ward. They converge near the scapula, and end in an aponeurosis, which glides over the smooth triangular surface on the medial end of the spine, to be inserted into a tubercle at the apex of this smooth triangular surface.

The middle trapezius fibres proceed horizontally. They are inserted into the medial margin of the acromion, and into the superior lip of the posterior border of the spine of the scapula.

At its occipital origin, the Trapezius is connected to the bone by a thin fibrous lamina, firmly adherent to the skin.

Functions of the Trapezius

The trapezius muscle has several functions:

• to move the shoulder blade in toward the spine,
• to rotate the shoulder blade so that the topmost part of the upper arm faces up,
• to move the shoulder blade up and down,
• to bring the head and neck in a backward direction,
• to rotate and side bend the neck, and
• to assist in breathing

You will use the trapezius muscles when shrugging shoulders and any overhead movements every day.

Some of the best exercises to strengthen the trapezius muscles include shrugs, reverse fly using a resistance band, lateral and forward neck flexion as well as neck rotation.

Common injuries to the trapezius muscles include tight muscles in the upper back and neck as well as postural kyphosis.

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