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deltoideus muscle
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The Human Body Illustration of the human neck showing labeled muscles, arteries, veins, and bones, including the sternocleidomastoid, digastric, mylohyoid, trapezius, carotid artery, jugular vein, clavicle, and thyroid cartilage. An anatomical illustration of the human upper limb and chest from the front, showing labeled muscles such as the deltoid, pectoralis major, biceps, triceps, and serratus anterior, along with the cephalic vein and thoracoacromial artery. An anatomical illustration of the human torso highlighting the muscles of the abdominal wall, with labeled structures including the deltoid, pectoralis major, serratus anterior, latissimus dorsi, external and internal oblique, rectus abdominis, and associated connective tissues. Illustration of the human back showing labeled muscles including trapezius, deltoid, latissimus dorsi, erector spinae, rhomboids, and gluteus maximus, with detailed anatomical structure. Detailed anatomical illustration of the human upper arm from the front, showing the superficial muscles, major nerves, and tendons. Key structures like the deltoid, biceps brachii, brachialis, and associated nerves are labeled. Illustration of the human upper arm from a posterior view, showing labeled muscles and nerves including the triceps brachii, deltoid, supraspinatus, infraspinatus, and several forearm extensor muscles. Posterior anatomical illustration of the human muscular system showing major back, arm, and leg muscles labeled, including trapezius, latissimus dorsi, gluteus maximus, and gastrocnemius.
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acromion
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deltoideus muscle

anatomy
Also known as: deltoid
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Britannica Editors
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proteinsHow proteins build muscle.
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deltoideus muscle, large, triangular muscle that covers the shoulder and serves mainly to raise the arm laterally. The deltoid, as it is commonly known, originates on the outer front third of the clavicle (collarbone) and the lower margin of the spine of the scapula (shoulder blade). Its fibres unite to form a thick tendon that inserts at the deltoid tuberosity, a rough spot above the middle of the outer surface of the humerus (upper arm bone).

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Michele Metych.