Learning Modules - Medical Gross Anatomy
Movements of the Upper Limb - Page 5 of 18


Arm Abduction

Abduction of the arm is also called abduction of/at the shoulder. This motion actually can be divided into two motions: true abduction of the arm at the shoulder and upward rotation of the scapula.

Muscles: supraspinatus (initiates abduction - first 15 degrees), deltoid (up to 90 degrees), trapezius and serratus anterior (scapular rotation, for abduction beyond 90 degrees).

The deltoid muscle abducts the arm, but at 90 degrees the humerus bumps into the acromion. Beyond this point, further abduction is the result of upward scapular rotation.

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