T HE DIAGNOSIS of thoraco-abdomina1 injuries requires menta1 projection of considerable knowIedge and more mental gymnastics and more finesse in management than aImost any other type of injury. The diagnosis of these injuries requires, as a minimum, a knowIedge of regiona anatomy and proper and compIete physica examinations. Certain anciIIary information is heIpfu1, but not essential to successfu1 diagnosis. This information covers such points as position of patient and assaiIant at the time of injury, type of instrument and manner of manipuIation or method of impact, and so forth. A detaiIed knowIedge of regiona anatomy is without question absolutely essentia1. One must practice drawing straight Iines through the body, using any point as the entrance of a buIIet, projecting the Iine in many different angIes and trying to visualize the various organs involved. To make this exercise a bit Iess arduous, the reader shouId know that in 90 per cent of buIIet wounds the course of the missiIe is straight from entrance to exit or to point of Iodging. The stories of buIIets or missiIes ricocheting around in circIes are oId wives’ taIes and can be readiIy expIained by knowing the position of the patient at the moment of wounding. For exampIe, a case was that of a soIdier hit by a single buIIet traveling in a straight line. (Fig. I.) This missiIe involved the Ieft Iower Iobe of the lung, diaphragm, stomach, Iarge bowel, spIeen and Ieft kidney. (Fig. 2.) This soIdier was Iying down with Ieft side up, facing up a hi& and was shot as the enemy came over the hilltop. A gIance at Figure z shows how straight was the buIIet’s course, but this is regional anatomy which was never taught in the past in medica schoo1 cross sectiona anatomy. Practice in projection of straight Iines traversing the body in many different directions is exceIIent preparation for proper diagnosis of organ invoIvement. KnowIedge of the mobiIity of organs and extremes of their dispIacement in the norma human being is vital. As an exampIe, a buIIet wound with entrance just media1 to the midcIavicuIar Iine anteriorly, entering the Ieft portion of chest through the third intercosta1 space (nicking the superior border of the fourth rib) and exiting posteroIateraIIy on a Iine paraIIe1 with the ground, resuIted in invoIving the stomach and spIeen. The answer simpIy is that the man was squatting and was in deep expiration at the time of wounding. The extremes of diaphragmatic excursion in deep inspiration and expiration are depicted in Figure 3. OccasionaIIy, one sees instances of wounding in which, at first gIance, ricocheting of the missiIe is seriousIy considered; for exampIe, a wound of entrance high in the chest anteriorIy with a missiIe found posteriorIy in the chest at the IeveI of the eIeventh rib posteriorIy. CIose examination of the roentgenogram reveaIed that the rib posteriorly, at the same IeveI of the anterior wound of entrance, had been fractured. Thus, the expIanation is simply that the missile traveling in a straight Iine hit a rib posteriorIy and (either having a Iow veIocity or near a high veIocity end point) was stopped by the posterior portion of the rib, dropped free in the pIeura1 cavity and came to rest deep in the posterior costophrenic angIe. KnowIedge of buIIet veIocity and the distance of air trave1 gives vaIuabIe information as to organ damage [I]. There is a direct proportion between the degree of organ damage and muzzIe veIocity. A missiIe of high velocity does far more damage by its “shock wave” than by the simpIe hoIe it makes. This is, of course, more evident in solid organs and is even more important in hemorrhage from late or delayed necrosis. In the use of knives, information as to the