Deltoids The Shape of the Shoulder

Editor's Note: When you see these three dots surrounded by a gray rectangle — 1 — you can click on it to get further information about the topic. Click a second time, and the message goes away.

This article was edited and updated on November 13, 2019.

Deltoids Shape your Shoulder

The shoulder is a ball-and-socket joint that allows us a tremendous amount of movement and flexibility. Nine muscles originate from the pectoral girdle and cross the shoulder joint to insert on the humerus (the upper arm).

The deltoids act as stabilizers and movers of the shoulder.

They have three parts: the anterior, the medial, and posterior. These three give that round look to your shoulder. 2

How do they attach to the bone?

The deltoids originate on the clavicle (collarbone) and from two places on the scapula (the shoulder blade); they then cross over the shoulder area; finally, they insert into the humerus (upper arm bone).

How do they help us?

The deltoids work together to help us move our arm in several ways:

What exercises can I do to strengthen the deltoids?

Using free weights (with a weight that is appropriate to your needs), here are four simple exercises to work the deltoids:

Other pages about other muscles:

I am a BCRPA-certified fitness instructor in Vancouver, BC. I teach four classes at the West End Community Centre in Vancouver, BC, mostly designed for the older adult. The Inevitable Disclaimer: Everything published here expresses only my opinion, based on my training and research. What you do with the information is entirely your own responsibility. I am not liable for any injury you suffer that seems to be related to anything you read here. Always consult your doctor before beginning an exercise program. For other articles, return to the table of contents.

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  1. These three dots behave exactly like a footnote. Click on them and you will get more information about the topic. 

  2. Thanks for the image of the deltoids from (although this website is apparently no longer active.)