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. Author manuscript; available in PMC: 2021 Apr 20.
Published in final edited form as: Thorac Surg Clin. 2021 Feb;31(1):1–10. doi: 10.1016/j.thorsurg.2020.09.007

Fig. 2.

Fig. 2.

Compression with movement of the scalene muscle. As the anterior scalene muscle goes from rest (A) to contracted (B), it pulls the first thoracic rib cranially and compresses the brachial plexus and subclavian within the costoclavicular space. Presence of a supernumerary cervical rib, as demonstrated in this figure, may constrict this space further. (From Adson AW. Surgical treatment for symptoms produced by cervical ribs and the scalenus anticus muscle. Surg Gynecol Obstet. 1947;85:687. Reprinted with permission from the Journal of the American College of Surgeons, formerly Surgery Gynecology & Obstetrics.)