The deltoid is a shoulder muscle that connects the clavicle, scapula and humerus together, allowing the arm to move freely in many directions. It is active in most movements that we do throughout the day - even walking! Anterior-Posterior-Anterior-Posterior :)
Drawing Deltoid
To visualize the deltoid muscle in 3-D on a real body, draw it on yourself or a partner. Here’s a video on how to. So simple, anyone can do it! Get a marker or paint. Washable might be preferred if you don’t want a tattoo for the rest of the day.
Turn up the volume, the music makes it :)
Uniqueness about Deltoid
Deltoid is both a synergist and an antagonist to itself! It has three main divisions: anterior, middle and posterior. The anterior portion technically divides further because it attached to two different bones (scapula and clavicle). When the sections all work together, abduction of the humerus happens. The anterior and posterior sections oppose one another in flexion and extension, also in medial and lateral rotation.
Origin: Lateral clavicle, Acromion process, Lateral spine of scapula
Insertion: Deltoid tuberosity
Actions: Abduction, Flexion, Extension, Medial & Lateral rotation, Circumduction
Deltoid in Yoga
Anytime the arm comes away from the body, deltoid is working: Low Lunge, Chair, Warrior, Triangle, Tree… It is contracting and stabilizing in dozens of other postures such as: Eagle, Tree, even in Lotus - the anterior fibers are shortening. Or, in Supine Twist, deltoid is most likely working to stabilize the torso.
The only time deltoid might not be contracting is in a posture like Mountain or Foot-Hand Pose.
Deltoid in Pilates
The same for Pilates, arms away from the body = Deltoid! The Hundred, Roll up, Double leg stretch, etc. When arms are resting on the ground for the floor series the deltoid might get a break, unless it is stabilizing the torso.
Deltoid Exercises
Common movements in the gym to strengthen deltoid are front, lateral and back raises. During bicep curls, tricep extensions and rotator cuff exercises deltoid is stabilizing and contracting, depending on form.
During a pull up the deltoid is an antagonist to the lats and lengthening or resting.
Deltoid Stretching
It is challenging to stretch the deltoid into its main antagonistic movement - adduction, because the torso is in the way! Yet, adducting and moving slightly anterior or posterior to the torso can provide a satisfying lengthening of deltoid. Also bringing the glenohumeral joint into horizontal adduction or abduction is a common stretch.
Deltoid Massage
Because of the limitations of stretching deltoid and since it is working 90% of the time (maybe even during sleep too!), massage is an excellent way to provide relaxation and lengthening of the deltoid muscle.
If you want to learn more about the nuances and possibilities of deltoid, check out one of my Integrative Anatomy CE courses. Live workshops in person and online are available and the online course you can take anytime at your own pace.
