Licence: Public Domain Mark
Credit: Memoir of the late Martin Barry, M.D., F.R.SS.L. and E. Source: Wellcome Collection.
Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.
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![d'2 In the fust tliiid of Hexioii, and in tlie latter tiiiid of extension, the niove- inents of the feimir and tibia take jjlace round the oblique curvature or ante- rioi thiid ot the internal femoral condyle; and involve, in addition to the completion and commeneement of flexion and extension respectively, a move- ment of rotation of tlie tibia, and, consequently, of the leg and foot inwards in the former, and outwards in the latter. These remarkable movements of rotation inwards and outwards, inseparable from the commeneement of flexion and the completion of^ extension, take jdace round the axis of the ideal cone already alluded to. This axis Jleyer denominates the oblique axis of the knee-joint. 1 liesc movements of rotation, combined witii fle.xion and extension, mu.st be carefully distinguished from thosi’ of which tiie joint is cajiable when consider- ably flexed. 1 he latter, with which anatomists are already familiar, take ]place, in general terms, round a prolongation of the axis of the tibia. This axis Meyer denominates the rotation axis of the knee-joint. .Mrti. next referrepl shortly to the actippii of the ligaments in the movements rounil the oblique axis of the j.dnt. Of these, the most remarkable is that of the external crucial, which ligament becomes tiglitened in extension, as the movement round the oblique curvature of the inner condyle proceeds, and thus acts, from its obliquity, in a direction from below, upwards, backwards, and outwards, so as to guide the rotation of the tibia outw.irds. The discovery of the oblique axis of the knee-joint h.'is enabled Meyer to determine with greater precision the action of certain muscles of the thigh. The use of the jpcculiar mode of insei tion, hitherto unex])lained, of the .sar- torius, gracilis, and semitendinosus, becomes evident. Their tendons passing down behind the inner side of the knee, curve forwards and outwanls on the tibia ; so that these muscles efl'ect that rotation inwanls, which is a nece.'.siiry accompaniment of the commencement of flexion. 'I'hese muscles jiroduee this rotation directly ; that is, l>y an adajptatimi of their tendons to the purpose ; hut, according to Meyer, the proper flexors of the knee, the biceps and semi- membranosus, only act indirectly as rotators, through the niediuin of the articular surfaces and ligaments. Mr G., however, conceives that the latter may act directly in jn-oducing rotation inwards at the commencement of flexion, fhr its teiuhm, iiisteail of being inserted, as is usually stated, into the back part of the inner tihial condyle, passes forwards and outwards round the head of the hone in a distinct grove, in which it moves, being kept in its place by prolongations of the internal lateral ligaments of the joint; and thus presenting the same general mode of insei tion as the three muscles already alluded to. The rotation outwards, at the completion of extension, is produced indirectly by the quadriceps-extensor ; the form of the articular sui-faces, and, according to Mr O., the tightening of the external ci ueial ligament, co-operating with the group of extensor muscles. Meyer has detected a very beautiful adaptation of parts in conuectiou with this latter movement, and has thus explained the characteristic enlai'gement, and the extensive attachment to the patella, of the vastus interiius mu.scle. When the knee is extended, the ligamentum patelhe, instead of being perpen- dicular, will be found to pass downwards and outwards to its tihial attachment, which has moved outwards in the rotation of the leg. The lower jiortion of the vastus iuteinus is enlarged, and the upjier portion of its tendon is attached to the greater pait of the inner edge of the patella, for the piirjiose of prevent- ing that hone from being pressed against the outer part of the femoral trochlea during the rotation outwards of the leg, by drawing it inwards and upwards, and keeping its axis in the line of the ligamentum jiatelltc; while the lower portion of its tendon jiasses dowm to he attached somewhat obliquely to the inner side of the head of the tibia, and thus a.ssi.sts dii-cctly in rotating the leg outwards. Meyer has also shown that, in standing quietly upright on one or both limbs,](https://iiif.wellcomecollection.org/image/b24931652_0012.jp2/full/800%2C/0/default.jpg)
