Deltoids: Definition and What it is

Medically and clinically reviewed by Jonathan Lee, MD and Dylan Peterson, PT, DPT

Deltoids Definition and Meaning

The deltoid muscles are a group of triangular-shaped muscles that surround the shoulder joint and give the shoulder its rounded shape. The deltoids start at the clavicle (collarbone) and scapula (shoulder blade) and insert into the humerus in the upper arm.

Deltoid muscles play a crucial role in shoulder movement and stabilization as well as various arm movements, including abduction, flexion, and rotation. The anterior (front) deltoid aids in arm elevation and rotation, the lateral (side) deltoid is responsible for lifting the arm away from the body, and the posterior (back) deltoid assists in arm extension and external rotation. 

Deltoid Exercises

Maintaining deltoid strength and flexibility is key to shoulder health. Regular exercises and stretches, like forward shoulder raises, thread the needle, and bird dog, can help prevent injuries and alleviate pain and discomfort in the shoulder and upper arm. 

Common Deltoid Muscle Injuries and Conditions

Deltoid injuries can range from minor strains to more serious tears. Deltoid muscle strains occur when one (or more) of the deltoid muscles over extend (or over stretch) and tear, leading to pain, bruising, swelling, and limited range of motion in the shoulder. Another common condition is tendinitis, in which the tendons connecting the deltoid muscle to the shoulder become inflamed. The deltoids can also play a role in shoulder impingement syndrome when the tendons of the nearby rotator cuff muscles become irritated and inflamed, leading to pain, weakness, and reduced shoulder mobility. In most cases, deltoid muscle injuries aren’t serious and can be treated at home with conservative measures. 

Deltoid Injuries: A Hinge Health Perspective

Your muscles — especially the muscle groups that support your shoulders — are very resilient and designed to recover from the kinds of issues that naturally can happen in the course of everyday activities or during exercise.

If you’re reluctant to move because you think you’ll cause more damage or injury to your shoulder area, know this: Movement is often the fastest way to healing. As our Hinge Health care team says, movement is medicine. Movement helps rehab the deltoids by increasing blood flow, and gradually improving their strength and flexibility.  

A physical therapist can work with you on a strengthening and stretching plan that not only alleviates immediate discomfort but also contributes to long-term health and function of the shoulder. You can see a physical therapist in person or use a program like Hinge Health to access a PT via telehealth/video visit.

How Hinge Health Can Help You 

If you have joint or muscle pain that makes it hard to move, you can get the relief you’ve been looking for with Hinge Health’s online exercise therapy program.

The best part: You don’t have to leave your home because our program is digital. That means you can easily get the care you need through our app, when and where it works for you. 

Through our program, you’ll have access to therapeutic exercises and stretches for your condition. 

Additionally, you’ll have a personal care team to guide, support, and tailor our program to you. See if you qualify for Hinge Health and confirm free coverage through your employer or benefit plan here.

This article and its contents are provided for educational and informational purposes only and do not constitute medical advice or professional services specific to you or your medical condition.


  1. Elzanie, A., & Varacallo, M. (2020). Anatomy, Shoulder and Upper Limb, Deltoid Muscle. PubMed; StatPearls Publishing. 

  2. How to Avoid Injuries to Your Rotator Cuff: Impingement Syndrome. (n.d.). Hospital for Special Surgery. Retrieved from 

  3. Walker, W. (n.d.). Deltoid. Physiopedia.

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