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Deltoid
Region
Origin & Insertion
['Origin: Lateral third of clavicle, acromion, spine of scapula', 'Insertion: Deltoid tuberosity of humerus']
Synergistic Muscles
['Rotator cuff', 'Trapezius']
Joints
['Glenohumeral joint']
Primary Actions
['Anterior: Shoulder flexion', 'Middle: Abduction', 'Posterior: Extension']
Nerve & Spinal Segment
Axillary nerve
Brachial plexus; C5–C6
Interesting
Divided into anterior, middle, and posterior fibers. [Netter’s]
Reversal of Action
Common Dysfunctions
Deltoid atrophy, weak shoulder abduction, axillary nerve injury
How to Stretch
Arm crossbody stretch or overhead reach.
Trigger Points
How to Strengthen
Isolated arm raises in 3 planes.
Concentric Action
Applications:
Eccentric Action
Isotonic Action
Related Conditions
['Rotator cuff injury', 'Shoulder impingement']
Isometric Action
Exercise Ideas
['Lateral raise', 'Front raise', 'Reverse fly']
Related Blogs
Images
Videos
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