deltoideus muscleArticle Free Pass deltoideus muscle, large,
triangular muscle that covers the shoulder and serves mainly to
raise the arm laterally. The deltoid, as it is commonly known,
originates on the outer front third of the clavicle (collarbone)
and the lower margin of the spine of the scapula (shoulder
blade). Its fibres unite to form a thick tendon that inserts at
the deltoid tuberosity, a rough spot above the middle of the
outer surface of the humerus (upper arm bone). What made you
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