The lateral border (or axillary border, or margin) is the thickest of the three borders of the scapula. It begins above at the lower margin of the glenoid cavity, and inclines obliquely downward and backward to the inferior angle. Immediately below the glenoid cavity is a rough impression, the infraglenoid tuberosity, about 2.5 cm. in length, which gives origin to the long head of the Triceps brachii; in front of this is a longitudinal groove, which extends as far as the lower third of this border, and affords origin to part of the Subscapularis. The inferior third is thin and sharp, and serves for the attachment of a few fibers of the Teres major behind, and of the Subscapularis in front. [ http://en.wikipedia.org/wiki/Lateral_border_of_the_scapula ]