Licence: Public Domain Mark
Credit: The anatomy of the human body / By J. Cruveilhier. Source: Wellcome Collection.
Provider: This material has been provided by the University of Massachusetts Medical School, Lamar Soutter Library, through the Medical Heritage Library. The original may be consulted at the Lamar Soutter Library at the University of Massachusetts Medical School.
201/944 (page 177)
![Mechanism of the Phalangal Articulations. As the mechanism of these joints is in every respect identical with that of the fingers, %ve shall refer to what has been said upon that subject, merely remarking that, either from original constmction, or from the continued confinement of the toes in tight shoes, their movements, which consist exclusively of flexion and extension, are much more limited than those of the fingers. Note on Arthrology.—\lt has been considered advisable to include in a single note the following observations on the general anatomy of the several tissues that enter into the construction of the articulations : Cartilages (p. 111).—The substance of the articular cartilages, in many joints, appears to be arranged in masses placed side by side, and perpendicularly to the surface of the bone ; and hence the fibrous character presented by them after slight maceration: nevertheless, they are composed of pure cartilage, unmiied with fibrous tissue. When viewed under the microscope, cartilage is found to consist of a transparent substance, in which are imbedded numerous corpuscles, either placed singly or aggregated in groups. The interme- diate substance is homogeneous in youlh, but becomes more or less laminated as age advances. The corpuscles, which are, in fact, metamorphosed primitive cells, are of irregular forms, contain nuclei and nucleoli, and are somewhat flattened near the surface of the cartilage. Occasionally, several are seen occupying a distinct cavity in the intermediate substance. Their average size is -pA^jth of an inch in length, byYT^Wth in breadth. Neither nerves, bloodvessels, nor lymphatics are found in the articular cartilages, which, al- though non-vascular, can scarcely be considered unorganized. Cartilage contains 66 per cent, of water ; its principal solid constituent is an animal matter, resolved by boiling into a peculiar variety of gelatin, called chondrin ; it also contains salts of soda, lime, magnesia, and potash. The inter-articular cartilages having free surfaces (as those of the knee-joint), are composed of true carti- lage interwoven with fibrous tissue, which particularly abounds at their attached margins. The inter-verte- bral substances, and aU other interosseous cartilages, have a similar structure, but contain a greater propor- tion of fibrous tissue. From the two anatomical elements of which these structures consist, they are called Jibro-cartilages. The articular borders surrounding the glenoid and cotyloid cavities, generally described with the ligaments, are also composed of fibro-cartilagiuous tissue. Ligaments (p. 112).—The articular ligaments consist entirely of fibrous tissue, the obvious component fibres of which are divisible into parallel micro.«;opic filaments, exactly similar to those of cellular tissue (see note on Aponeurologt, infra). They are supplied with but very few vessels and nerves ; they contain 62 per cent, of water, the remainder being almost entirely converted into gelatin by boiling. The yellow elastic tissue, of which the ligamenta subflava are composed, differs in minute, as well as in ob- vious characters, from the white fibrous tissue of ordinary ligaments. It consists chiefly of peculiar filaments, intermixed with a few of those of cellular tissue. The proper elastic filaments, examined with the micro- scope, are yellowish and transparent, have a bright aspect and dark outline (very unlike the delicate appear- ance of the cellular filaments), and are usually curied or bent at iheir torn extremities. The peculiar char- acter of dividing and uniting again, often assigned to them, is thought to be rather apparent than real, and to depend on an imperfect separation of the larger into their component filaments. The elastic is more vascular than the fibrous tissue. It contains less water (only 29 per cent.), and yields much less gelatin when boiled: the insoluble residue somewhat resembles coagulated albumen. Synovial Membranes (p. 112).—The basis of an articular synovial membrane is cellular tissue, which be- comes more and more condensed towards the free surface of the membrane. The smoothness of this surface is due to a covering of flattened scales (metamorphosed primitive cells) lying upon it, and constituting what is termed an epithelium. The recent discovery of this epithelium upon the surface of the articular cartilages is sufficient to establish the continuity of the synovial membrane over them ; a fact which, though doubted by many, is assumed by M. Cruveilhier upon analogical grounds. No nerves have been traced into these mem- branes, and the vessels existing in the sub-synovial tissue cease at the margin of the cartilage. The syno%-ia secreted by these membranes is an aqueous solution of albumen and saline matters. It contains more albu- men than the fluid of serous cavities, the lining membranes of which (as we shall hereafter notice) have a similar structure to those just described. Besides the articular synovial membranes, two other kinds are usually mentioned, viz., the bursal, including the various bursae, erroneously called bursae mucoss ; and the vaginal, examples of which are met with in the sheaths of tendons. These two forms will be again referred to in the note on Aponeurology, infra. Adipose Tissue.—The constant occurrence, especially in the larger articulations, of masses of fat beneath the synovial membranes, affords an opportunity of alluding in this place to the minute anatomy of the adipose tissue generally. It may be briefly stated to consist of an aggregation of distinct spherical or oval vesicles, containing the adipose substance, and having numerous vessels ramifying on their transparent and homoge- neous parietes. They are held together by the branches of those vessels, and bj'cellular, tissue. In man, the adipose substance is liquid during life, but separates, when obtained in any quantity, into an oily fluid called elaine, and a solid residue, consisting of two fatty substances, stearine and margarine.] ODONTOLOGY. Circumstances in which the Teeth differ from Bones.—Number.—Position.—External Confor- mation. —General Characters. —Classification—Incisor—Canine—Molar.—Structure.— Development. The teeth, the immediate instruments of mastication, are those ossifonm concretions which surmount the edges, and are implanted in the substance of both jaws. The teeth are not bones, though, from possessing an apparent analogy to them, they have long been considered as such. They differ from bones in many respects. 1. With regard to positimi. The teeth are naked and visible at the surface, while the bones, and this is one of their most important characters, are covered by periosteum. 2. In anatomical characters. The teeth consist of a bulb or thick papilla, surrounded by a calcareous envelope, composed of two substances, the enamel and the ivory. This calcareous envelope is not traversed by vessels, nor can any trace of cellular tissue be discovered in it. 3. In regard to their mode of development. In the teeth, the formation of the hard or ossiform matter takes place by successive depositions, from the circumference to the cen- Z](https://iiif.wellcomecollection.org/image/b21196801_0201.jp2/full/800%2C/0/default.jpg)
