The anterior fibers of the deltoid originate from where?

• A. Acromion.
• B. Lateral third of the clavicle.
• C. Spine of scapula.
• D. Coracoid process.

Answer: (B)

Anterior fibers of the deltoid come from the lateral third of the clavicle. The deltoid has three parts with distinct origins: the anterior portion attaches to the lateral third of the clavicle, the middle portion to the acromion, and the posterior portion to the spine of the scapula. This arrangement explains the actions: the anterior fibers help flex and medially rotate the arm, the middle fibers abduct the arm, and the posterior fibers extend and laterally rotate the arm. The coracoid process isn’t a deltoid origin, and the acromion and spine of the scapula are the origins for the middle and posterior fibers, respectively.