Quadrangular space

The quadrangular space (or quadrilateral space [of Velpeau] or foramen humerotricipitale) is an axillary space in the arm. This is a clinically important anatomic space in the arm. In the quadrangular space, the axillary nerve and posterior circumflex humeral artery can be compressed or damaged due to space-occupying lesions or disruption in the anatomy due to trauma. Symptoms include axillary nerve related weakness of the deltoid muscle in the case of any significant mass lesions in the quadrangular space.