Macalister — On the Morphology of Joints. 781 



XCV. — On the Moephologt of Joints. (Part First.) By Alex. 

 Macalister, M.D., P.E.S., Professor of Anatomy, tfniversity of 

 Dublin. 



[Eead, February 26, 1883.] 



In most of the systematic treatises on Human Anatomy the descrip- 

 tions of the articulations are usually defective and unsatisfactory. 

 The importance of these structures from a surgical point of view 

 caused the anatomists of the end of the last and early years of this 

 century to devote much care to their investigation, and subsequent 

 describers have for the most part been content to follow the accounts 

 of Weitbrecht, Bell, the Coopers, Cloquet, and their contemporaries. 



As a consequence of this, the morphological relations of the struc- 

 tures entering into the joints have been largely disregarded, and their 

 anatomy is described from the strictly utilitarian, and not from the 

 scientific, point of vioAV. 



The method followed in the dissections of the joints hinders our 

 recognition of the real nature of these parts. In general all the 

 collateral parts are cut away before the ligaments are considered, and 

 hence bands are often described as substantive ligaments which are 

 really deeper attachments of superficial parts. 



In the course of a careful series of researches, carried on for the 

 purpose of Terifying in detail the materials accumulated by me for a 

 systematic treatise on Human Anatomy, I have been much impressed 

 by the unsatisfactoriness of the state of our knowledge of the mor- 

 phological anatomy of joints, and I shall, therefore, in this communi- 

 cation, and in those that follow it, endeavour to contribute to the 

 clearing of some of this obscurity. Much of what I shall have to 

 describe is, I doubt not, very well known to those engaged in practical 

 anatomical work, but has not hitherto been put on record. 



I have endeavoured to determine the history of the individual 

 joints by the twofold method of embryology and ontology, and in this 

 Paper I desire to summarize some of the general results of my studies. 



The embryological history of the larger limb- joints in man may be 

 summed up thus : — At first, on the appearance of the limb, the axis or 

 core thereof consists of undifferentiated mesoblastic cells. In this cen- 

 tral mesoblast a process of chondrification commences in the areas 

 wherein the several bones are afterwards to be. In this state are the 

 limbs of the smallest embryo examined by me, one of 21 cm. long. This 

 transfoimation begins in limited, nearly central spots, and spreads until 

 it results in the formation of a discontinuous chain of cartilages in the 

 axis of the limb, each cartilage corresponding in place to the bone into 

 which it is about to develop. The end of each of these is attached to 

 the contiguous end of its neighbour by a mass of embryonic connective 

 tissue Avhich fills up the interspace, and which is similar in structure 

 to the primitive unchondrified axis, and to the investing layer, which 



