VARIATIONS OF ORIGIN AND DISTANCE OF AXILLARY NERVE: A DESCRIPTIVE STUDY

Description

Background: Axillary nerve, one of the terminal branches of posterior cord of brachial plexus is more prone for injuries. Lack of proper anatomical knowledge and variations of axillary nerve leads to risk of nerve injuries. The present study describes the origin of axillary nerve, its distance of origin from tip of coracoids process. Method: Thirty brachial plexuses from fifteen formalin fixed human cadavers of both the sexes were studied by dissection method. Origin and branching pattern of axillary nerve and its distance of origin from the anteromedial aspect of tip of coracoid process & posterolateral aspect of acromion process was recorded. Results: Out of the 30 specimens studied, axillary nerve was originating from the posterior cord of brachial plexus in 90% of specimens, remaining 10% specimens showed a common trunk of origin of axillary nerve from posterior cord of brachial plexus. The mean distance of origin of axillary nerve from the anteromedial aspect of tip of coracoid process and posterolateral aspect of acromion process is 3.98cm & 6.30cm respectively. The axillary nerve terminated into anterior and posterior branch within quadrangular space in 29 specimens. In one specimen articular branch for shoulder joint was not directly arising from axillary nerve instead it is arising from anterior branch of axillary nerve. Conclusion: In studied population Axillary nerves display variations in the origin and distance of origin. Knowledge of this variation in axillary nerve is very important to clinicians, anaesthetists and orthopaedic surgeons during surgical exploration of neck, axilla and upper arm, shoulder dislocation, infraclavicular brachial plexus block and fracture of surgical neck of humerus.
Keywords: Axillary nerve; Posterior cord; Coracoid process; Acromion process.