Trapezius muscle
The trapezius muscle is a large muscle in the
back that extends from the base of the
skull to the mid-back, attaching to the
scapula (shoulder blade),
clavicle (collarbone), and the length of the
spine. There is one trapezius on each side of the back.
The trapezius is a superficial
muscle that serves a number of important functions for movement. Daily use involves shrugging the shoulders and overhead movements. As a whole, it provides support to the
spine and neck and enables arm, neck and shoulder movement. It also serves to stabilize, raise, retract (bring together) and rotate the
scapulae. Another function of the trapezius is as a
breathing muscle. Though not as powerful as the
diaphragm for this use, it can help to open the upper chest area to allow a small amount of breathing room.
The three regions of the trapezius are the superior (upper), intermediate (middle) and inferior (lower) fibers. The superior region works to elevate the scapula, or shrugging the shoulders upward. The middle fibers raise, rotate and pull the
shoulder blades back and together. The lower region helps to arch the upper back, move the
shoulder blades, and enable
lateral raising and rowing movements.
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Origin
The trapezius has a complex origin along the back of the
vertebral column extending from the base of the
skull to the last
thoracic vertebra. It attaches at the
medial third of the
superior nuchal line, the
nuchal ligament, the
spinous processes of C7-T12 - the seventh
cervical vertebrae and all (T1-T12) the
thoracic vertebrae, and the
supraspinous ligament above C7-T12.
Insertion
The trapezius has a complex insertion at the back of the shoulder, where it attaches to the
scapula (shoulder blade) and the
clavicle (collar
bone). The upper fibers
insert at the
lateral third of
posterior border of the
clavicle. The lower fibers
insert at the
medial
acromion process and the superior lip of the
spine of scapula.
Word origin
The name trapezius comes from the trapezoidal shape made by the right and left triangular-shaped sides.