It is a four sided pyramidal space between root of arm and chest wall. It allows the passage of the nerves and blood vessels from neck to upper limb.
Upper-Extremity Peripheral Nerve Blocks in the Perioperative Pain Management of Orthopaedic Patients by Umasuthan Srikumaran, Benjamin E. Stein, Eric W.
بسم الله الرحمن الرحيم
