Shoulder Muscles - Deltoids

Shoulder Muscles - Deltoids

The shoulder muscles (deltoideus muscles, deltoids or delts) have its name from its delta shape (triangular shape) and is located on top of the shoulder joint. Its function is to elevate the arm. The side head does most of the work until the arm reaches 60 degrees. From there, the front and the rear head do most of the work. The deltoid muscle forms the round contour of the human shoulder. Find exercises and information about other muscles at weight training main.


  • The shoulder muscles consist of three deltoid heads.
    • Pars Clavicularis - Front Head - Front Deltoids
      For example when you lift something in front of you.
      (with your thumbs pointing up)
      Typical Exercise: Front Dumbbell Raise
    • Pars Acromialis - Side Head - Mid Deltoids
      Works when you lift something sideways.
      Typical Exercise: Side Lateral Raise with Dumbbells
    • Pars Spinalis - Rear Head - Rear Deltoids
      Typical Exercise: Reverse Fly
  • A typical shoulder exercise very good for overall strength and volume is the barbell military press. When you sit upright, you work your entire shoulder. But when you adjust the back lean lower, you work the front head of your shoulders more than the other heads. If you lean back too far, it's not a shoulder exercise anymore. Instead, you are bench pressing on an incline bench.


  • When you do front dumbbell raises or side lateral dumbbell raises, it's not recommended to lift the weight over horizontal level. The function of the deltoid is to lift the arm and press the upper arm bone into the shoulder joint. When you lift the arm too high, the angle from which the deltoid works, and the weight, can harm the shoulder joint. When you do a military press, the triceps and other muscles do a part of the work and give the joint more stability.
  • One of the best exercise to train the rear heads of your deltoids is the reverse fly.
  • To avoid shoulder problems, train all 3 heads of your deltoids.
  • The only shoulder exercise that's adequate for heavy weights is the military press.
  • Gain shoulder strength with the barbell military press or the handstand push up.