Priyanjith's Forensic Medicine & Medical Ethics: Bullet entry and Puppe's rule

Entry wound of a Bullet Injury

Situated on the left squamous temporal bone is a obliquely placed oval bone deficiency measuring approximately 10 mm x 5 mm centred approximately 70 mm above and 40 mm in front of the external acoustic meatus. The posterior end is lying inferiorly. The edges are regular with possible inner bevelling. At the lower end are two radiating fissured fractures. One extends downward and forward and the other extends downward and backward and ends at another fissured fracture, which extends upward and backward from the base of the skull (middle cranial fossa) and disappears on the left occipital bone.

The fissured fracture extends downward from the bone deficiency ends at the third fissured fracture indicating the former occurred after the latter.

(Puppe's Rule- In cases of Multiple Gun shot injuries sequence of shots may be deduced from Puppe's Rule. Puppe's rule states that an extending fracture line will cease if it meets a preexisting fracture or suture line.)

Conclusion

There should be another bullet entry wound on the other side of the skull, which produces the 'third' fissured fracture described above and that bullet entry wound should have been inflicted before the injury shown in the picture.

How did we conclude that this is a bullet injury?

The size and shape of the injury and the presence of multiple radiating fractures indicate that this is likely to be a bullet injury. The other possible weapons, which is likely to cause similar injury on the skull are blunt pointed instruments such as pick axe. They are unlikely to cause radiating fracture and regular oval or rounded deficiencies. Even if they do they never cause 'interal bevelling', which is the 'hallmark' of 'bullet' injury (both inner and outer bevelling).