176 MR WM. TURNER ON VARIABILITY IN HUMAN STRUCTURE. 



related with corresponding variations in the external configuration of the body, 

 yet there are a large number which, either from their minuteness, or from being 

 situated in the deeper seated parts, give no sign externally, and to distinguish 

 them requires close and careful dissection. For many years I have been in the 

 habit of preserving a record of the most remarkable " irregularities," as they are 

 often called, which have come under my notice ; and I could cite many cases 

 from my note-book in which, in the course of dissection, variations in the different 

 organic systems were noted. During the present winter session, for example, 

 four arms have been met with in which that very curious process of bone, 

 known as the supra-condyloid process, projected from the inner part of the shaft 

 of the humerus. In all, this process was connected to the inner condyle by 

 a ligament. The process, the ligament, and the shaft of the humerus, covered by 

 the brachialis anticus muscle, formed collectively the boundaries of a supra-con- 

 dyloid foramen. In all the median nerve went through the foramen. So far 

 these limbs, though varying greatly from the usual arrangement of parts in the 

 human upper arm, corresponded closely with each other, but in other respects 

 they differed considerably amongst themselves. In three specimens the pronator 

 radii teres muscle arose from the process and the ligament connecting it to the 

 condyle ; in the fourth the pronator muscle did not arise from these structures, 

 but the ligament gave origin to some of the fibres of the brachialis anticus muscle. 

 In one specimen the brachial artery, after giving off an accessory radial artery 

 high up in the limb, accompanied the median nerve through the supra-condyloid 

 foramen ; in another the brachial artery, after giving off its ulnar branch of 

 bifurcation high up in the limb, also passed along with the median nerve behind 

 the process; in the third, the brachial artery pursued its usual course along the 

 inner margin of the biceps to the bend of the elbow previous to its bifurcation, 

 and sent simply a small branch through the foramen along with the median 

 nerve ; in the fourth not only was the brachial artery not deflected from its cus- 

 tomary course, but it did not even send a small branch through the foramen, 

 through which, consequently, the median nerve proceeded unaccompanied by any 

 vessel.* In three of the specimens, also, a muscular slip arose along with the 



* The four cases described in the text of the occurrence of a supra-condyloid foramen in the 

 human upper arm are not the only specimens which have come under my notice in the dissecting- 

 room. In former years I had observed five specimens, in three of which both brachial artery 

 and median nerve passed through the foramen, in the remaining two I had unfortunately not pre- 

 served a note of the arrangement. But by far the most complete account of the anatomy of the 

 supra-condyloid foramen which has yet appeared has been drawn up by Professor Wenzel Grueer 

 in an elaborate memoir presented to the Imperial Academy of St Petersburg. Vol. viii. 1859. 

 This anatomist has collected from the works of previous writers, as well as from material which 

 has come under his own observation, sixty-two cases in which this foramen was noticed in the human 

 body, and in which there was at the same time a greater or less amount of variation in the arrange- 

 ment of the pronator teres, the median nerve, the brachial artery or some of its branches. One of 

 the chief features of interest connected with the supra-condyloid foramen is the circumstance that 

 it furnishes, as an occasional occurrence in human structure, an approximation to an arrangement 



