Question

Function of the deltoid

Answer 1

Ans:- The deltoid muscle is like three muscles in one: the
anterior fibres flex the arm, lateral fibres abduct the arm and
posterior fibres extend the arm.

Actions
1. The anterior (clavicular) fibres are flexors and medial
rotators of the arm.
2. The posterior (spinous) fibres are the extensors and
lateral rotators of the arm.
3. The middle (acromial) fibres are the strong abductor of
the arm from 15° to 90°.

Other functions include

Provinding stability to shoulder joint.

Protect underlying Nevers like axillary nerve and vessels like post and ant circumflex artery from traumatic damage.