The role of the first rib in the scalenus anterior syndrome.

The scalenus anterior muscle was first believed by Murphy (1905) to play a part in the production of symptoms by a cervical rib and since then its importance in a proportion of these cases has been recognised. Adson and Coffey (1927) claimed that division of the muscle, without resection of the cervical rib, was sufficient to relieve symptoms. Naffziger (quoted by Ochsner, Gage and De Bakey 1935) drew attention to the scalenus anterior as the possible cause of symptoms even in the absence of a cervical rib. This condition, in which the symptoms of a cervical rib occur in the absence of the rib itself, was called the scalenus anterior syndrome by Ochsner et al. (1935). Since then the suggestion that the muscle could cause pressure on the brachial plexus and subclavian artery has been widely, though not universally, accepted ; but in recent years doubt has been increasing. The exact mechanism by which it could give rise to the symptoms has always been in dispute. Patients with scalenus anterior syndrome-used as a general term to include all those with symptoms of pressure in the cervico-brachial region but no cervical rib-can be divided into two groups: 1) those with a scalenus minimus, a ligamentous band or similar abnormality; and 2) those in whom the anatomy appears normal. The second group present the chief etiological problem and provide the basis for the present study.