Anatomy and Deficiency of the Deltoid Muscle: A Review of Literature.

Background/objective: The deltoid muscle is impacted by common injuries and clinical procedures. This study aims to summarize the anatomy, injuries, and clinical considerations involving the deltoid muscle.

Method: A literature search was performed using PubMed and Google Scholar using keywords that focused on the deltoid muscle in the shoulder. Primary research articles and appropriate summary articles were selected for review.

Results: Reduced deltoid muscle function can be caused by axillary nerve injury, rupture of the deltoid itself, or iatrogenic damage to the muscle. The deltoid muscle has an intimate relationship with the axillary nerve and neighboring rotator cuff muscles. Injury to these nearby structures may be masked by compensating deltoid strength. Examination maneuvers in clinic such as the Akimbo Test should be used to isolate the deltoid muscle to determine if the presenting weakness is from the deltoid itself or from other surrounding injury. Additionally, prior to performing clinical procedures, it is important to be cognitive of the injuries that can occur. For example, incisions that extend distally from the acromion should not extend beyond 5-7 cm as this is the common location of the axillary nerve and vaccine administration should take measures to avoid misplaced injections to avoid unnecessary trauma.

Conclusion: Deficiency of the deltoid muscle can be debilitating to patients and it is best clinical practice be aware of the anatomy, various causes, tests, and avoidance measures to help diagnose, restore or preserve normal functioning.