• Every vertebra has a costal element. In the thorax, the costal elements break free and form the ribs. If the C7 vertebra also frees that element, a cervical rib is formed; its size is variable. Bands run from the tip of the bone to the cervical rib and may compress or irritate the lower trunk.

• A variety of surgical approaches have been described for those few patients who suffer from thoracic outlet syndrome and require surgery. We favor an anterior dissection, because we believe that the irritation and compression of plexus elements is at a proximal level and from a variety of causes, and that the affected elements of the plexus should be safely decompressed under direct vision.

• The skin incision is made slightly above the clavicle and parallel to it (Figure 5-1). Depending on preexisting incisions and the patient’s body habitus, the medial end of the incision may be extended upward or the lateral end of the incision may be extended downward over the deltopectoral groove.

• The clavicular head of the sternocleidomastoid is divided, leaving a cuff on the clavicle for subsequent reattachment. There is no need to divide the sternal head. This maneuver is preceded by passage of a finger behind the lower lateral border of the clavicular head to ensure that all venous structures are separated from the deep surface of that muscle.

• If the external jugular vein impedes progress, it should be divided.

• The phrenic nerve is dissected free of the underlying scalenus anterior and is guarded throughout the operation.

• The scalenus anterior is divided close to its tendon. The divided muscle springs apart, and all bleeding points within the muscle belly are secured (Figure 5-2). It is not reattached at the end of the operation.