Referred to as AC. The acromioclavicular (AC) joint is located between the acromion (part of the scapula (shoulder blade) that forms the highest point of the shoulder) and the clavicle (collarbone)

Acromion is the highest point of the shoulder.

Agility is the ability to change the body's position efficiently, and requires the integration of isolated movement skills using a combination of balance, coordination, speed, reflexes, strength, endurance and stamina.

Antagonist is the negative/opposite/opponent muscle and agonist is the positive/the one in focus (prime mover). If you are reading about the biceps muscle as the prime mover, that would be the agonist. The antagonist is then the triceeps. That's the opposite muscle of the biceps. The muscle that counteracts the agonist (or the prime mover); lengthening when the agonist muscle contracts.

And this also goes the other way around. If you're talking about the triceps muscle, then that would be the agonist. And that makes the bicpes muscle the antagonist.

Antagonist is the negative/opposite/opponent muscle and agonist is the positive/the one in focus (prime mover). If you are reading about the biceps muscle as the prime mover, that would be the agonist. The antagonist is then the triceeps. That's the opposite muscle of the biceps. The muscle that counteracts the agonist (or the prime mover); lengthening when the agonist muscle contracts.

And this also goes the other way around. If you're talking about the triceps muscle, then that would be the agonist. And that makes the bicpes muscle the antagonist.

The muscles placed on the front side of the body is called anterior muscles. The front of the shoulder is called anterior deltoid. The back is called posterior deltoid. It's only muscles that goes front to back, that have this description