Cervical Rib Anomaly
Could present with TOS symptoms as this is a contributing factor in 1% of the population with neurogenic TOS and venous TOS. Usually this affects roots C7-T1 as it travels between the anterior and middle scalenes. Management of chronic inflammation in the area is most important. A cervical rib anomaly is accepted as a case of true TOS.
(Watson et. al., 2009)
(Watson et. al., 2009)