Supra-scapular nerve impairment in missed posterior dislocation after electrocution

The principal causes of posterior dislocations with or without fracture of the humerus are epileptic seizure, violent trauma directly on the anterior face of the shoulder or indirectly in a fall on outstretched arms, and accidental or therapeutic electric shock [3-5,7]. In this position, the head of the humerus is drawn upwards and backwards, behind the acromion and inwards behind the glenoid fossa by contraction of the infraspinatus, teres minor, teres major, deltoid and latissimus dorsi muscles [2,4,5]. Because of the violence of the movement with the head of the humerus behind the glenoid fossa, a fracture may occur.