How to Identify the Deltoid
The deltoid is the muscle that forms the contour of the shoulder and is frequently used as a site for intramuscular injections. This muscle is important in body building and has three heads. The front deltoid is most commonly isolated with dumbbell raises, the middle deltoid may be trained with shoulder fly exercises and the rear deltoid is best worked with the inverted fly. Here's how to identify the deltoid muscle.
Instructions
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Read up on Greek roots to know that deltoid means "triangular." This muscle is roughly triangular in shape.
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Examine the deltoid to see that it abducts arm flexion. The anterior portion medially rotates the arm and the posterior portion extends and laterally rotates the arm. All three portions of the deltoid are opposed by the latissimus dorsi.
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Observe how the anterior deltoid originates from the lateral and anterior 1/3 of the distal clavicle, the middle deltoid originates from the lateral border of the acromion and the posterior deltoid originates from the scapular spine.
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Look at the insertion of all three heads of the deltoid into the deltoid tuberosity of the humerus via a thick tendon.
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Research the nervous system to know that the nerve for the deltoid is the axillary nerve from the fifth and sixth cervical nerves. Study the circulatory system to know that the blood supply for the deltoid is the posterior humeral circumflex artery and the deltoid branch of the thoracoacromial artery.
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