Which term refers to the muscle's moveable or distal attachment?

• A. Insertion
• B. Origin
• C. Flat muscle
• D. Pennate muscle

Answer: (A)

In muscle anatomy, the end that moves when the muscle contracts is the insertion, the distal attachment. The opposite end, the origin, is the proximal attachment that tends to stay relatively fixed during movement. Terms describing whether a muscle is flat or pennate refer to fiber arrangement, not to where the muscle attaches. For example, a muscle may originate on one bone and insert on another; when it contracts, the insertion is pulled toward the origin, producing movement at the joint. This is why the distal attachment is called the insertion.