The coraco-clavicular joint.
The present study shows that the coraco-clavicular joint should be recognised as a normal human joint that is present in a large number of people of all races. Its presence does not confer any overt advantage but neither does it give rise to any trouble. It is possibly an evolutionary joint that has arisen from the approximation of the clavicle to the coracoid and new conditions of use in man where complex movements are possible at the shoulder. The genetic basis for this joint has been elucidated and it is inherited in a simple Mendelian fashion.
D002968:Clavicle / Q000033:anatomy & histology*; D006801:Humans; D012540:Scapula / Q000033:anatomy & histology*