196 SURGICAL APPLIED ANATOMY. [Chap. xi. 



bone occur before the age of five years. This is ex- 

 plained by the fact that the bone is ossified at a very 

 early period, and is in a breakable condition at a time 

 when most of the other long bones still present much 

 unossified cartilage in their parts. Moreover, the 

 periosteum of the clavicle is unduly thick, and not 

 very closely attached to the bone, circumstances that 

 greatly favour subperiosteal fracture. 



A reference to the relations of the bone will 

 show that important structures may be wounded in 

 severe fractures associated with much displacement 

 and with sharp fragments. Several cases are reported 

 of paralysis of the upper limb (as a rule incomplete) 

 following upon fracture of this bone. In some cases 

 this symptom was due to actual compression, or 

 tearing of some of the great nerve cords by the dis- 

 placed fragments. In other cases the nerve injury, 

 while due to the original accident, was yet indepen- 

 dent of the broken clavicle. Cases are reported of 

 wound of the subclavian artery, of the subclavian vein, 

 of the internal jugular vein, and of the acromio-thoracic 

 artery. In several instances the fracture has been 

 associated with wound of -the lung, with or without a 

 fracture of the upper ribs. 



The clavicle begins to ossify before any bone in 

 the body. At birth the entire shaft is bony, the two 

 ends being still cartilaginous. The bone has one 

 epiphysis for its sternal end that appears between the 

 eighteenth and twentieth year, and joins the shaft 

 about twenty-five. It is a mere shell, is closely 

 surrounded by the ligaments of the sternal joint, and 

 cannot, therefore, be well separated by accident.* 



Steruo-clavicular joint. A though this is 



* Mr. Heath (Lancet, Nov. 18, 1882) reports a case which is 

 probably unique. It concerns a lad, aged 14, who, when in the 

 act of bowling at cricket, tore the clavicle away from its epiphyseal 

 cartilage, which remained in situ. The muscle producing the 

 accident was apparently the pectoralis major. 



