Final answer:
When discovering and naming a new muscle group under the arms, use criteria such as muscle number, locations, attachment points, origins, and functions. Terms like 'bi-' for two origins, or 'abductor' for the action can be useful.
Step-by-step explanation:
When naming muscles of a new species, you should consider criteria such as the number of muscles in a group, their location in the body, the location of attachments to the skeleton, the number of origins a muscle has, or the action of the muscle. For a muscle group under the arms, you should note that muscles in the upper limb can be divided into groups that stabilize the pectoral girdle, move the arm, move the forearm, and move the wrists, hands, and fingers. For instance, if the muscle group under the arms serves to stabilize the pectoral girdle, terms reflecting their function, location, and anatomical characteristics would make sense. Thus, if the muscles have two origins, a prefix such as 'bi-' could be helpful, akin to the biceps brachii, or if they are involved in abduction, the term 'abductor' might be appropriate.