Tlespite the cliriical importance of the duodenum there is little accurate information concerning either its position or mobility. Although text books of amtomy place the first part of the duodenurn opposite the first lumbar vertebra and the third palst opposite the third lumbar rertebra, it is acknowledged that these positions may n r y . Roentgenologists a r e frequently struck by the fact tliat the viscus occasionally extends into the pelvis, but no significance can be attached to the tincling, sirice it is riot known whether this falls outside of the normal range. On the other hand, so frequently does the source of a gastroiiitestirial corriplaiiit remain obscure that it ~~-.c-oulcl be valuable to know whether inalposition or fixation of' the duodenum might sometirnes be a causal factor. Recognition of such aberrations presupposes a knowledge of the n o ~n i a l range of variation. The present study was undertaken to establish the noimal position aiid mobility of the cluoclenuni as well as its variability in the living subject.
Tlie suhjects who form the basis of the present investigaed froin a series of over 2500 consecutive patients iweiving routine R.oentgenologic examinations of the miall bowel, performed in the Royal Victoria Hospital. From this series all cases which revealed definite pathological c~nitlitioiis, either recent o r old, of either tlic small or large This 11 01k wa8 carried on with thr finnnci:d a i d of the Rlnnrhe Hutchinuon Pnt~il