The neural supply of the trapezius is the spinal accessory nerve (C1-C5).The neural supply of the deltoid is via the axillary nerve (C5, C6) from the posterior cord of the brachial plexus.The neural supply of the supraspinatus is by the suprascapular nerve (C5, C6) from the upper trunk of the brachial plexus.The circumflex scapular artery is the blood supply to the serratus anterior.The transverse cervical artery provides vascular supply to the trapezius.The posterior circumflex humeral artery and the deltoid branch of the thoracoacromial artery are the vascular sources for the deltoid.The suprascapular artery delivers blood to the supraspinatus muscle.The muscles of arm abduction, like all muscle within the body, except for a few exceptions, is mesodermal in origin during the development of the embryo. The trapezius and serratus anterior coordinate with each other and the scapula to facilitate abduction of the arm upwards of 90 degrees. The deltoid controls abduction from 15 to 90 degrees. The supraspinatus is the primary muscle for the abduction of the arm to 15 degrees. Four different muscles control this action: supraspinatus, deltoid, trapezius, and serratus anterior.
#ABDUCTION OF ARM FULL#
The ability to abduct the arm is a crucial contributor to the full range of motion of the arm. (The upper extremity action during a jumping jack can is exemplary of the full range of motion for arm abduction.) The primary muscles involved in the action of arm abduction include the supraspinatus, deltoid, trapezius, and serratus anterior. The abduction of the arm begins with the arm in a position parallel to the torso and the hand in an inferior position, continues with the movement of the arm to a position perpendicular to the torso, and ends with the movement of the arm so that the humerus is raised above the shoulder joint and points straight upward. In the case of arm abduction, it is the movement of the arms away from the body within the plane of the torso (coronal plane). In general terms, abduction, in the anatomical sense, is classified as the motion of a limb or appendage away from the midline of the body.
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