128 THE HEAD AND NECK 



operations, or if the arms have been allowed to hang down unsupported from 

 the operating table. Further, recent observations have shown that symptoms 

 ascribed to the presence of a cervical rib may in reality be due to the first 

 (thoracic) rib. Moreover, the first rib has been partially removed in some 

 cases, with complete disappearance of the symptoms. 



Cervical Rib. The ventral portion of the transverse process 



FJG. 41. Bilateral Cervical Ribs. Viewed from behind. The cervical 



ribs are considerably foreshortened. 



of a cervical vertebra is homologous with a thoracic rib, and is 

 termed the costal element. In the case of the sixth and seventh 

 cervical vertebrae the costal elements frequently develop from 

 independent secondary centres of ossification, and occasionally 

 they undergo abnormal development so as to form cervical ribs. 

 The condition may be unilateral or bilateral, and varies from a 



