If, says Boyer, the soft parts were in the natural state, we could easily recognise the fracture of the coracoid process, when it has occurred ; but so much force is necessary to produce this fracture, that the considerable swelling which alwaysaccompanies it, prevents us from being able to recognise the characters of the injury, so that it is not generally as certained except in the dead body.
C. Fracture of the neck of the scapula.— By a fracture of the neck of the scapula is nieant a fracture through the narrow part of the bone immediately beneath the notch on the coracoid margin of the scapula, by which, the glenoid or articular portion of the bone, together with the coracoid process, becomes detached from the rest of the scapula ; the head of the humerus falls into the axilla, with the glenoid cavity attached to it by means of the capsular ligament.
Sir Astley Cooper says the diagnostic marks of this injury are three : first, the facility with which the parts are replaced; secondly, the immediate fall of the head of the bone into the axilla when the extension is removed ; and thirdly, the crepitus which is felt at the extremity of the coracoid process when the arm is rotated. The best method for dis covering the crepitus is as follows ; let the surgeon's hand be placed over the top of the shoulder, and the point of his forefinger he rested on the coracoid process ; the arm being then rotated, the crepitus is distinctly per ceived, because the coracoid process being attached to the glenoid cavity, and being broken off with it, although itself uninjured, crepitus is communicated through the medium of that process. We believe this accident to be exceedingly rare.
D. Fracture of the superior extremity of the humerus. — The superior extremity of' the humerus may be broken across, in the line of its anatomical neck, or through the head of the bone above this oblique line. In both cases the fracture will be intra-capsular.
Secondly, the fracture may be extra-cap sular, passing through the tubercles; beneath the anatomical neck of the humerus, yet above the line of the junction of the epiphysis, with the shaft of the bone.
Thirdly, a fracture may traverse the hu merus in the line of junction of the epi physis with the shaft of this bone, or close to this line.* Fourthly, the humerus may be fractured in the part called the surgical neck, beneath the line of junction of the epiphysis with the shaft.
1. Intracapsular fracture of the humerus.— We find on record fractures of the head of the humerus, which were altogether intra articular ; and in these cases the head of the bone was separated at the proper anatomical neck. Boyer states he has met with many
such cases, most of which were fatal from the severity of the injuries which accompanied the fracture. He mentions the case of a woman who lived for seven days, after having received one of these severe injuries. On making a post-mortem examination of the shoulder, the separated head of the huinerus had suffered a great loss of substance; it was hollowed out as to its fractured surface, so as to represent a complete hollow cap or " ca lotte." It seems to be the opinion of many, that in cases of intra-capsular fractures of the superior extremity of the humerus, unless some portions of synovial membrane and periosteum remain unbroken, no bony consoli dation can occur. This may be true as to some fractures ; but, on the other hand, we have evidence of cases in which the head of the humerus must have been completely broken, as well as all its membranous cover ings severed ; and yet perfect reunion of the portion of bone which had been detached was established ; but in these cases it is to be observed, that impaction, to a certain degree, of the head of the humerus into the shaft, had occurred.
The possibility of the consolidation, by bony union of a fracture of the anatomical neck of the humerus had been long doubted. Upon this subject, J. Cloquet observes : " I have, some years ago, made known a case of fracture of the humerus through its anatomi cal neck, which had been perfectly united. Rachel had before published a similar fact: sometimes the consolidation in these cases would appear to he accomplished by the agency of' the inferior fragment, from which spring up stalactiform productions, which surround and encase the superior fragment." He adds, " we have also met with examples, in which consolidation did not take place. In these last cases, the head of the bone has been found to have been hollowed out, by contact with the inferior fragment, so that a false joint had been formed in the situation of the fracture; and the superior fragment, by its inferior surface, represented a hollow cup, or calotte articulaire.'"* The following cases will show that a frac ture through the anatomical neck of the hu merus may occur, in which the head of the bone may be subsequently impacted into the shaft, and be then consolidated by bony union.