Final answer:
The deltoid muscle originates from the scapula, clavicle, and humerus. It is crucial for various shoulder movements such as abduction and rotation, contributing to the rounded shape of the shoulder.
Step-by-step explanation:
The origin of the deltoid muscle is on the scapula, clavicle, and humerus. This muscle is important for shoulder movements including abduction, flexion, and rotation.
The deltoid is among the group of muscles that cross the shoulder joint to move the humerus. Its rounded appearance characterizes the silhouette of the upper arm and shoulder.
Other muscles that play a role in shoulder movement include the subscapularis, supraspinatus, infraspinatus, teres major, teres minor, and coracobrachialis, which also have their respective origins on the scapula.