136 REPORT — 1855. 



On the Use of the Round Ligament of the Hip- Joint. 

 By Dr. John Struthers, F.R.C.S., Lecturer on Anato^ny, Edinbtirgh. 



By removing tlie bottom of the acetabulum so as to expose the round ligament 

 from behind, while its attachments and those of the capsular ligament are left 

 entire, the author has been able to aftbrd actual demonstration of the use of this 

 important ligament. On moving the femur in the various directions, it is now seen 

 that the ligament becomes quite tight only in rotation outwards. It approaches the 

 tight condition in adduction, — the motion which this ligament has more recently 

 been supposed to check, so as to support the body on the femur in the erect 

 posture ; but extreme adduction docs not actually stretch the ligament. In ro- 

 tation outwards, however, the ligament is so much stretched as to be flattened upon 

 the bone, and is perfectly tight. It is not tightened in rotation inwards, as this is a 

 more limited motion than rotation outwards. This being the fact, the reason seems 

 to be, that it is in this motion, rotation outwards, that the femur is naturally most 

 liable to, and would otherwise leave the socliet. To prevent this there are two pro- 

 visions,— the great thickness of the front half of the capsular ligament, and, in- 

 terraally, the round ligament. By adopting this method of demonstration, any 

 anatomist may satisfy himself as to these statements. It must be granted that the 

 ligament can be of use only in that position in which it becomes tight. 



On the Explanation of the Crossed Influence of the Brain. 

 By Dr. John Struthers, F.R.C.S., Lecturer on Anatomy, Edinburgh. 



The object of this paper was to show that the decussation of the anterior py- 

 ramids of the medulla oblongata affords only a partial explanation of the phsenomena 

 of crossed nervous influence. This was made evident by the want of proportion or 

 correspondence between the phjenomena and the amount of decussating matter, which 

 does not include above one-third of even the cerebral portion of the medulla oblongata; 

 while the influence of each side of the brain, as regards both motion and sensation, 

 is usually entirely crossed upon the opposite side of the bod}', as seen in cases of 

 palsy, putting aside in this argument the results of experiments on the lower 

 aniinals. The statements as to exceptional cases in human pathology, are not 

 unlikely to have had their origin in mistakes in the use of the terms right and left. 



Further, we have evidence of the influence having crossed a considerable distance 

 above the decussation of the pyramids, in the fact, which the author's own ob- 

 servation attested, that in cases of palsy of one side of the body, accompanied by 

 palsy of the face, the two palsies were on the same side, and therefore on the 

 opposite side to the cerebral lesion. 



The conclusions drawn were — 



1. That the influence of the brain is entirely crossed, one side of the body being 

 set on the opposite side of the brain for both motion and sensation ; unlike the 

 optic decussation, which is a half decussation, serving a special purpose in the 

 equal reflex regulation of the pupils. 



2. That the phsenomena could not therefore be explained unless by a complete 

 decussation of each lateral half of the descending fibres of the brain. 



3. That the decussation of the anterior pyramids does not form more than about 

 a fourth part of the anatomical decussation or decussating channel. 



4. That the situations in which the rest of the fibres passed, or might pass, across 

 the middle line, are (a) the middle line of the pons, where especially the fibres of 

 the great crus cerebelli may decussate, and thus readily explain the crossed influence 

 of the cerebellum, which could not be well explained through the restiform body. 

 (6) The middle line, or so-called septum, of the medulla oblongata, (c) The white 

 commissure of the spinal cord in its whole length. In these situations there is no 

 coarse decussation like that of the pyramids, but ample space for a complete de- 

 cussation, by a finer admixture of the whole of the descending fibres of the brain. 



