When the tracks penetrated the broad upper intercostal spaces, an interesting feature, due to the tense and rigid nature of the muscles closing the intervals, and their large admixture of fibrous tissue, was sometimes noticed. The bullet, especially if passing obliquely, was apt to cut a slit in the muscles far exceeding in size the opening in the overlying integument, with the result of leaving a palpable subcutaneous defect. Under these circumstances the yielding spot was often noticed to rise and fall with the movements of respiration, external palpation met with an absence of normal resistance, and there was impulse on coughing.
Fractures of the ribs.—These injuries were produced in either transverse or longitudinal coursing tracks, their special feature being a sharp localisation of the lesion of the bone.
In tracks crossing the chest transversely the injury to the ribs might consist in notching, perforation, or complete solution of continuity, sometimes with fine comminution. In the incomplete injuries some importance attached to the localisation of the lesion to the upper or lower border of the rib, in so far as the intercostal artery was concerned. Comminution at the wound of entry was, as a rule, not so extensive as at the aperture of exit, and in any case was less apparent, since the fragments were driven inward. The wider comminution at the exit aperture depends on the lesser degree of support afforded by the thoracic coverings to the convex outer surface of the rib, and on the fact that the velocity of the bullet has been lowered by its passage through the opposite rib and the chest cavity.
The splinters of comminuted ribs are small, and wide-reaching fissures rare. These characters depend on the elastic nature of the resistance offered by the curved rib to the passage of the bullet, which is calculated to preserve the bone from the full force of impact, except at the point actually impinged upon.
Fractures of the ribs, produced from within by bullets taking a longitudinal course through the thorax, were still more special in character. They were also more important, as giving rise to troublesome symptoms.
In these, again, the degree of injury to the bones varied considerably. In some cases the bones were merely grooved internally, without any external deformity; in other cases a sort of green-stick fracture was produced, accompanied by the projection of a tender salient angle externally; in others complete solution of continuity was effected.
Another feature of importance was the occasional implication of several ribs. In this case the symptoms accompanying the injury were very much more like those observed in the corresponding injuries resulting from indirect violence seen in civil practice.
Injuries to the costal cartilages closely resembled those to the ribs. Perforation, bending from injury to the inner aspect, and comminution were observed. The latter condition differed from the similar one seen in the case of the ribs only in so far as the tougher consistence of the cartilage did not lend itself to such free comminution, and the splinters remained in great part attached. The nature of the fractures, in fact, somewhat resembled that seen on breaking a piece of cane.
I saw no fracture of the sternum except of the nature of a pure perforation; these were not uncommon in the hospitals, either in the upper or the extreme lower portions of the bone. Fractures in other portions were no doubt usually associated with fatal injuries to the heart. The openings were usually so small as to be difficult of palpation, and I never had the opportunity of examining one post mortem.
Perforations of the body of the scapula were common, but they were of little importance in symptoms or prognosis.