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Trapezius

Other Terms: Trapezius muscle, Musculus trapezius, Muscle trapèze

Muscle parts

Descending or superior part; Transverse or middle part; Ascending or inferior part

Latin name

Musculus trapezius

Latin muscle parts

Pars descendens; Pars transversa; Pars ascendens

Group

Branchial arch muscle – transition arch or Pectoral girdle muscle

Etymology

In English, this muscle’s name is the four-sided muscle. The term trapezius is derived from the Greek trapeza meaning a “four-legged table”, which arose from tetra meaning “four” and pesa for “foot.” The term trapezium took on the extended designation of a four-sided shape from the appearance of the table’s top. The trapezius is the only muscle in the body whose name arises from the combined left and right muscles. Individually the muscle has a triangular shape.

Origin

External occipital protuberance, nuchal ligament, and spinous processes of 7th cervical and all thoracic vertebrae

Insertion

Lateral third of the clavicle and the acromion and spine of the scapula

Action

Upward rotation of the glenoid cavity – when the head is fixed, the cranial fibers elevate the acromial end of the clavicle causing the glenoid cavity of the scapula to rotate upward (cranially). By pulling downward on the medial-most aspect of the scapular spine, the inferior fibers also rotate the glenoid cavity upward. Adduction (retraction) of the scapula – the middle fibers adduct (retract) the scapula. Depression of the scapula – the inferior fibers, directed downward, assist gravity in depressing the scapula from an elevated position. Extension of the head – when the pectoral girdle is fixed the superior fibers help extend the head. Working with the other scapular muscles, this muscle helps to stabilize the scapula and its associated glenoid cavity to improve the functional efficiency of the muscles working at the shoulder joint.

Nerve supply

Accessory nerve (Cranial nerve XI)

Blood supply

Superficial cervical artery or its variation the superficial branch of the transverse cervical artery; a branch of the suprascapular artery; and perforating branches from the posterior intercostals arteries. The cranial end of the muscle also receives branches from the occipital artery.

Latin

Musculus trapezius

French

Muscle trapèze

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