The anatomic relationships of the axillary nerve and surgical landmarks for its localization from the anterior aspect of the shoulder

The axillary nerve has long been known to be one of the nerves vulnerable to damage during shoulder arthroscopic and open surgical procedures. The relationship of the axillary nerve to the shoulder capsule and the subscapularis muscle has not been well defined in orthopedic literature. This descriptive anatomical study aimed to present the course and the relations of the axillary nerve with neighboring neurovascular structures and the shoulder capsule and to define anatomical landmarks and regions that can be used practically in anterior surgical approaches to the shoulder region. To investigate the course of the axillary nerve and its relationship with neighboring structures, 30 shoulders of 15 fixed adult cadavers were dissected under the microscope through an anterior approach. A triangle-shaped anatomic area containing the axillary neurovascular bundle was defined. The closest distance between the axillary nerve and the anteromedial aspect of the coracoid tip and the glenoid labrum was measured as 3.7 cm and 1.1 cm on average, respectively. The distance between the anteromedial aspect of the coracoid tip and the point where the nerve passes through the medial edge of the subscapularis was measured as 2.5 cm on average. The results of this study demonstrate the anatomic pattern and the course of the axillary nerve and its relations with the shoulder capsule. Knowing the exact localization of the axillary nerve under the guidance of the defined anatomic triangle may provide a safer surgery.