Final answer:
When naming muscles based on the location of attachment, the origin of the muscle is named first, followed by the insertion. Anatomists also use muscle shape, size, number of origins, location, and fiber direction to name muscles.
Step-by-step explanation:
When naming muscles based on the location of attachment, the origin is named first. For example, the sternocleidomastoid muscle has its origin at the sternum and clavicle, and inserts on the mastoid process. The insertion always comes after the origin in the muscle's name. Additionally, muscle names may indicate the action they perform, with terms such as flexor, extensor, abductor, or adductor, reflecting the type of movement the muscle generates.
Anatomists also consider other factors when naming muscles, such as their shape, size relative to the surrounding muscles, the number of origins they have, their location in the body, and the direction of their fibers.