Suprascapular and axillary nerves of right side, seen from behind. Quadrangular space is the lateral space, labeled in green at center right. Axillary nerve is visible entering it.
The scapular and circumflex arteries. (Quadrangular space is visible but not labeled. Posterior humeral circumflex artery is visible entering quadrangular space at center right.)
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 as it provides the anterior regions of the axilla a passageway to the posterior regions. 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.
It is bounded by:
- above/superior: the teres minor (inferior margin).
- below/inferior: the teres major (superior margin)
- medially: the long head of the triceps brachii (lateral margin)
- laterally: the surgical neck of the humerus
- anteriorly: the subscapularis