Final answer:
Skeletal muscles are named based on features such as their number of origins, location, attachments, and action. Biceps indicates a muscle with two origins, while abductor denotes a muscle's action to abduct, or move away from the body's midline.
Step-by-step explanation:
When anatomists name skeletal muscles, they often use terms that indicate specific characteristics of the muscle, such as the number of origins, location, attachments, shape, size, and action. For example, the muscle name biceps suggests it has two origins, indicated by the prefix bi-. In contrast, a muscle such as the abductor indicates its action, which is to move a bone away from the midline of the body.
Now considering the provided names:
- Internal rectus - This refers to an eye muscle, and its name implies its location and orientation within the body, particularly as it pertains to other similar muscles.
- Biceps - As previously discussed, the prefix bi- indicates this muscle has two origins.
- Abductor - This muscle is named for its action, which is to abduct a limb or part away from the body's midline.
Understanding these terminologies helps in identifying the movement and function of intrinsic skeletal muscles of various body parts, including those of the back, neck, abdominal wall, and thorax.