The quadrangular space is defined by:[2] The quadrangular space transmits the axillary nerve, the posterior humeral circumflex artery and the posterior circumflex humeral vein.

Other common causes of axillary nerve compression at the quadrangular space include local compression due to osteophytes which are common in osteoarthritis, shoulder dislocations, fractures of the humeral neck, repetitive use, and external pressure (such as from crutches).

Symptoms of axillary nerve compression include axillary nerve related weakness of the deltoid muscle (shoulder abduction) and teres minor (external rotation of the arm) as well as numbness of the lateral shoulder.

The quadrangular space is the most common site of axillary nerve compression.

This article incorporates text in the public domain from page 589 of the 20th edition of Gray's Anatomy (1918)