A 52 year old woman presented with weakness of shoulder movements. Investigations revealed quadrangular space syndrome. Which of the following nerve is likely to be affected ?

Quadrangular space is a passageway for the nerves and vessels between the axilla anteriorly and scapular region posteriorly. It&;s contents are Axillary nerve Posterior circumflex humeral aery and vein Quadrangular space syndrome is a condition caused by hyperophy or fibrosis of quadrangular space muscles which impinge on axillary nerve. Patient present with weakness of shoulder movements. Ref : Gray&;s Anatomy The Anatomical Basics of Clinical Practice 41 e pg 814.