Deltoid Muscle: Patterns of Innervation from Axillary Nerve

Introduction The injury of the axillary nerve has been reported and it shows weakness of the deltoid muscle, mainly after intramuscular injections. The wrong site of these injections can cause this complication. A sharp knowledge of the deltoid muscle's innervation can avoid this iatrogenic occurrence Study objective Determine patterns of deltoid muscle's innervation (from the axillary nerve) in order to establish a danger area (to be avoided during injection procedures) Material and Methods Two dissections were performed stratigraphically in human cadavers. 1. Longitudinal incision in the proximal region of the arm ( anterior) 2. The muscle was all exposed, their insertions were divided, and its deep part was exposed. 3. This maneuver permitted to find the axillary nerve and its branches Taking the view of the nerves, we made projections of the entry points in the muscle using a Cartesian coordinate system (the referential point was the greater tubercle of the humerus). The group of these points, when projected in the coordinated system, defined an area where, in the superficial part of the muscle, we can predict the entry of the branches of the nerve in the muscle. Summary of Results Preliminary results show that nerve entry points are distributed predominantly in the middle region of the deltoid muscle across the longitudinal axis of it. This area is an ellipsoid shape. Conclusion Our data can help avoiding iatrogenic injuries during procedures and, they also help understanding the myofascial pain and its treatment.