Trapezius muscle

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This article is about the human skeletal muscle. For the trapezius muscles found in cats, see trapezius muscles (cat).

Trapezius
Image:Trapezius.png
Trapezius.
Image:Gray409.png
Muscles connecting the upper extremity to the vertebral column. (Trapezius visible at upper right.)
Latin	musculus trapezius
Gray's	subject #121 432
Origin:	arises, down the midline, from the external occipital protuberance, the nuchal ligament, the medial part of the superior nuchal line, and the spinous processes of the vertebrae C7-T12
Insertion:	at the shoulders, into the lateral third of the clavicle, the acromion process, and into the spine of the scapula
Blood:
Nerve:	major nerve supply is the cranial nerve XI. Cervical nerves C3 and C4 receive information about pain in this muscle
Action:
Dorlands/Elsevier	m_22/12551283

In human anatomy, the trapezius is a large superficial muscle on a person's back.

1 Actions
2 Nomenclature
3 Exercise
4 Anatomical details
5 Variations
6 Additional images
7 External links

[edit] Actions

Because the fibers run in different directions, it has a variety of actions, including:

scapular elevation (shrugging up),
scapular adduction (drawing the shoulder blades together)
scapular depression (pulling the shoulder blades down)

Different fibers control different actions:

The superior (upper) fibers elevate the scapula.
the middle fibers retract it.
The inferior (lower) fibers depress it.
When the superior and inferior fibers act together they superiorly (upwardly) rotate the scapula.

[edit] Nomenclature

Trapezius gets its name from its trapezium-like shape; the corners being the neck, the two shoulders, and the thoracic vertebra, T12.

The word "Spinotrapezius", when applied to humans, refers to the trapezius, although it not commonly used in modern texts. In other mammals, it refers to a portion of the analogous muscle, it gives you a sort of a Arch on/near your neck. See trapezius muscles (cat) for more details.

[edit] Exercise

The trapezius can be developed by elevating the shoulders. Common exercises for this movement are shoulder shrugs and upright rows.

A person can feel the muscles of the trapezius become active by holding a weight in front of them in one hand, and with the other, touching the area between the shoulder and the neck.

[edit] Anatomical details

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 vertebræ, and from the corresponding portion of the supraspinal ligament.

From this origin:

the superior fibers proceed downward and lateralward. They are inserted into the posterior border of the lateral third of the clavicle.
the inferior fibers proceed upward and lateralward. 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 fibers 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.

At the middle it is connected to the spinous processes by a broad semi-elliptical aponeurosis, which reaches from the sixth cervical to the third thoracic vertebræ, and forms, with that of the opposite muscle, a tendinous ellipse.

The rest of the muscle arises by numerous short tendinous fibers.

The two Trapezius muscles together resemble a trapezium, or diamond-shaped quadrangle: two angles corresponding to the shoulders; a third to the occipital protuberance; and the fourth to the spinous process of the twelfth thoracic vertebra.

[edit] Variations

The attachments to the dorsal vertebrae are often reduced and the lower ones are often wanting; the occipital attachment is often wanting; separation between cervical and dorsal portions is frequent.

Extensive deficiencies and complete absence occur.

The clavicular insertion of this muscle varies in extent; it sometimes reaches as far as the middle of the clavicle, and occasionally may blend with the posterior edge of the Sternocleidomastoideus, or overlap it.

[edit] Additional images

Muscles of head and neck.	Left clavicle. Superior surface.	Section of the neck at about the level of the sixth cervical vertebra.	Surface anatomy of the back.
The left side of the thorax.

[edit] External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.