Quadrangular space

Quadrangular space
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.)
Anatomical terminology []

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 an 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:

It transmits the axillary nerve and posterior circumflex humeral vessels (artery and vein).

Muscles on the dorsum of the scapula, and the Triceps brachii.

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)