Trapezius

Trapezius - also known as our 'traps' - can be divided into 3 sections based on the muscle fiber direction. Upper, Middle, and Lower (fibers)

image on left c/o wikipedia

Muscle Attachments Points:

(there are lots for this one!)

Origin: 
a) external occipital protuberance 
 (bony bump on the back of your head)

b) the medial 1/2 of the superior nuchal line and the nuchal ligament 
 (back of head and ligament on back head and down the neck)


AND c)  spinous processes of C7-T12

(bumps on the back of your spine - from the bottom of your neck to the bottom of your ribcage!)

Insertion:  
d) Lateral 1/3 of the clavicle, the acromion process and the spine of the scapula
(end of your collarbone where it meets the shoulder > wrapping around back to the (top of the) shoulder blade.

Muscle Actions:

Muscle movements change depending on attachment points and muscle fiber direction.

Because Trapezius spans across almost our entire back, AND has 3 different fiber directions, we'll divide Trapezius actions by its upper, middle, and lower sections:

                                        Upper:  elevation, retraction & upward rotation

                                        Middle: retraction

                                        Lower: depression

*all these movements are of the shoulder blade (aka Scapula) at scapulo-costal joint.

(where the front (anterior) of the shoulder blade meets the rib cage.)

Trapezius... it's the squeeziest (!)