Variations in the Accessory Structures of the Clavicle: Findings at Chest Radiographs and Dry Bones

Abstract

Purpose : To evaluate normal variations and thus to avoid confusion in differentiation form lesions of theaccessory structures (rhomboid fossa, foramen for supraclavicular nerve, conoid tubercle) of the clavicle in chestradiographs. Materials and Methods : We studied the variations of the clavicle in 300 chest radiographs (134 men,166 women) and 355 dry bones (right 166, left 189 ; 151 men, 74 women, 130 unknown sex). Results : In chestradiographs, the incidence of the depressed rhomboid fossa was 229 cases (39.5%;male 52.0%, female 29.9%); theflat type was 329 cases (56.9%;male 45.7%, female 65.7%); and the elevated type was 20 cases (3.5%;male 2.4%,female 4.3%). In the dry bones, the incidence of the depressed rhomboid fossa was 129 cases (57.3%;male 59.6%,female 52.7%); the flat type was 65 cases (28.9%;male 24.5%, female 37.8%) and the elevated type was 31 cases(13.8%;male 15.9%, female 9.5%). The incidence of the foramen for supraclavicular nerve was 0.8% in chestradiographs, and 1.4% in the dry bones. The incidence of the elevated conoid tubercle was 64.1% (male 64.0%,female 65.9%) in chest radiographs, and 96.9% (male 95.4%, female 100.0%) in the dry bones. Conclusions : Theincidence of the depressed rhomboid fossa in chest radiographs was higher in men and the right clavicle. Theincidence of flat rhomboid fossa in chest radiographs decreased according to increase of age. The foramen forsupraclavicular nerve was occasionally found (0.8% in chest radiographs; 1.4% in the dry bones).