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Upper limb anatomy

Muscle	Origin	Insertion	Innervation	Function
Deltoid muscle	The anterior or clavicular fibers arises from most of the anterior border and upper surface of the lateral third of the clavicle. Lateral or acromial fibers arise from the superior surface of the acromion process of the scapula. Posterior or spinal fibers arise from the lower lip of the posterior border of the spine of the scapula.	Middle of the lateral aspect of the shaft of the humerus	Axillary nerve	The prime mover of arm abduction along the frontal plane. The arm must be medially rotated for the deltoid to have maximum effect. This makes the deltoid an antagonist muscle of the pectoralis major and latissimus dorsi during arm adduction.