A triangular muscle that caps the shoulder and produces most arm-lifting movements.
Structure
The deltoid has three sets of fibers: anterior fibers from the clavicle, middle fibers from the acromion, and posterior fibers from the spine of the scapula. They all converge on the deltoid tuberosity of the humerus.
Function
Anterior fibers flex and internally rotate the arm. Middle fibers abduct the arm away from the body. Posterior fibers extend and externally rotate it.
Clinical note
The thick lateral deltoid is a common site for intramuscular injections, since it offers an easy target with few major vessels or nerves at risk.
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Deltoid starts with D . Browse other body parts along the same letter.
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