It appears that the fascicle length of the trapezius in the fibers inserting on the clavicle and acromion range between 62 — 104 mm and 65 — 125 mm, respectively (Kamibayashi et al. 1998). (strengthandconditioningresearch.com)
The middle head, which starts more central, i.e. on the acromion, and attaches to the outer portion of the humerus. (fitnessandpower.com)
Impingement, which happens when tendons of the rotator cuff muscles become inflamed or irritated when passing though the subacromial space, the passage under the acromion. (fitnessandpower.com)