Deltoids – The Sexy Shoulder Muscle!

Hey everyone!

Welcome back or welcome to the page!

Today I would like to continue my series of articles on the thirteen different muscle groups. Today we will talk about the deltoids, the muscle that is on your shoulder. We will talk about where it attaches, what it does, and how to stimulate growth.

Let’s get started!

All About the Deltoiddeltoid

The deltoid is a large muscle in the uppermost part of the arm, forming the rounded part of the shoulder. It is attached to the skeleton in various places, and has many functions. One of its primary functions is to move the arm around the shoulder joint. The deltoid raises the arm in front of the body and raises the arm to the side of the body. This causes the deltoid to be the antagonist to the pectoral muscles which pulls the arm toward the centre line of the body. The pectoralis major and the deltoid work together to move the arm away from and toward the body.

Since the deltoid attaches at three different places, it can be divided into three specific sections: the anterior, the middle, and the posterior.

Let’s talk about the three sections

Clavicular, Acromial, and Scapular Deltoids


The deltoid is a rather large muscle. So large, in fact, that it originates at three different parts of the skeleton. All three parts converge together and attach to the part of the humerus known as the deltoid tuberosity.

In the front, the anterior deltoid attaches to the clavicle, very close to the lateral fibers of the pectoralis major. This part of the deltoid is responsible for flexion and internal rotation of the arm (opposite of what the pectoralis major does).

The acromial portion (middle part) of the deltoid originates around the acromion, which is the upper most bony part of the shoulder blade. This part of the deltoid is responsible for the abduction (raising outward) of the arm past the 15 degree mark. This abduction is initiated by a small muscle in the back called the supraspinatus. Together, these two muscles raise the arm.

At the back, the posterior deltoid originates on the lateral 1/3 of the scapula (shoulder blade) and is responsible for the extension and external rotation of the arm.

When all is said and done, the shoulder (deltoid) is responsible for (with the assistance of a lot of other muscles) all the movements of the arm, as can be seen in the diagram below.

shoulder actions

All The Actions Of The Shoulder

In this chart, you can see the many motions of the arms and shoulders and the muscles that are responsible for the motion. Of interest is that it takes two sets of muscles to move your arm, for example up and down. One set to move it up; one set to move it back down. The same can be said for all skeletal parts. Try some of the actions in the chart, paying particular attention to the muscles involved. This will be important in the next section when we talk about the best exercise to build a strong, sexy deltoid.

Action of the Shoulder What the Action Looks Like

(Try It Yourself!)

Primary Muscles
Shoulder abduction Lift your arms out to the side Deltoid: all fibers and supraspinatus
Shoulder adduction Lower your arms to your side Pectoralis major and latissimus dorsi
Shoulder flexion Lift your arms in front of you Pectoralis major, and anterior fibers of the deltoid
Shoulder extension Return (lower) your arms from shoulder flexion or lift your arms behind you Latissimus dorsi, teres major (“little lat”)
Internal shoulder rotation From the anatomical position, rotate your arm so that the elbow faces forward.

This action at the shoulder can occur when your arm is in different positions (flexion, abduction, etc.).


Latissimus dorsi and pectoralis major

External shoulder rotation From a position of internal shoulder rotation, rotate your arm so that the elbow faces backward. Also, anatomical position requires the shoulders to be in external rotation.

This action at the shoulder can occur when your arm is in different positions (flexion, abduction, etc.).

Infraspinatus and teres minor
Horizontal abduction For the start position, lift your arms in front of you. The action occurs as you then move your arms out to the side. Latissimus dorsi and posterior fibers of deltoid
Horizontal adduction From the starting position, lift your arms out to the side. The actions occurs as you then move your arms in front of you Pectoralis major and anterior fibers of deltoid

Shoulder Exercises

Once again, as in all the sections on exercises, there are many exercises and many opinions on which are the best exercises. Since there are three major parts of the deltoid, based on the origin of that portion of the muscle, you should be doing exercises that will specifically build up that part of the muscle.

That being said, any shoulder exercise will engage at least a portion of each of the three parts of the deltoid.

I will give you a few examples of exercises to use to build the deltoid. Keep in mind that the deltoid is a large muscle and is very visible. Building the deltoid even a little bigger will give the illusion of being more muscular.

Keep in mind that I am suggesting that you do a version of these exercises. The exercises shown here are done with dumbbells, but many of these could be done with a barbell or on a machine with cables.

I would suggest that you work your shoulders with the following exercises once per week. Perform three sets of 12 – 15 repetitions of each exercise, choosing a weight that allows for perfect form. It is too easy to injure the shoulder with too much weight and poor form.

Remember, you do not have anything to prove to anyone by lifting heavier weights, and an injury could keep you out of the gym for months. Be sensible and reasonable and only challenge yourself to a heavier weight when all fifteen reps in each set are super easy.

deltoid exercises

One other exercise that I would be remiss to not mention is the face pull.

face pullAs you can see in the photos, a face pull is done with a rope attached to a cable. It could also be done with a resistance band. Start with your arms out in front of your face. As you pull the rope or resistance band toward your face, flare your hands out beside your face. Repeat for 12 repetitions. Do three sets.

The face pull is an important exercise to perform for the overall health of the shoulder. It also contributes to good posture. The face pull will work the rear deltoids, the rotator cuffs, the traps, and many of the small muscles in the back that we cannot usually target. Doing a few sets of 15 with a moderate weight will be really good for the overall health of your shoulders and for preventing injuries.

Last Words

So there you have it.deltoids

The function of the deltoids and the exercises to help them grow. The deltoids are one of three muscles that will make you look more muscular with just a little more size. The other two are the trapezius and the latissimus dorsi. I’ll get to those in the next two articles.

Thanks for listening.

If you have any questions or comments, please leave them below.

Also, if you are a father (or mother) (or anyone for that matter) who would like an easy to follow program that includes a menu and work out information, check out this article from a few months ago.

See you in the next post.

Have a great day!


Tom Fitzsimmons

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