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.
193/944 (page 169)
![great toe. In order to see the deep layer of this hgament, the superficial layers must be removed one after the other. The tibio-tarsal articulation belongs to the class of angular ginglymi. Articular Surfaces.—Both bones of the leg participate in this joint, their lower extrem- ities being united to form a transversely oblong socket, of which the tibia constitutes by far the greater part. On this articular surface there is an antero-posterior ridge, corre- sponding to the groove of the trochlea on the astragalus, and separating two shallow cav- ities. The socket is bounded by the malleoli on each side. The internal or tibial mal- leolus corresponds to the internal lateral articular surface of the astragalus ; and the ex- ternal or fibular malleolus, to the external lateral facette of the same bone. The tibio- peroneal cavity is completed forward and backward by the lower part of the anterior and posterior peroneo-tibial ligaments. The superior articular surface of the astragalus is a trochlea ; it is oblong from before backward, thus contrasting with the cavity on the lower extremity of the leg,* which is transversely oblong. This trochlea presents a shaUow depression, running from before backward, and having an external and an internal edge, the external being the more elevated of the two. The pulley of the astragalus is continuous with its lateral articular surfaces, of which the external is by far the larger. The means of union are three external lateral ligaments, two internal lateral hgaments, an anterior (r, fig. 80) and a posterior (s, fig. 79) ligament, and a synovial capsule. The external lateral or. j>eroneo-tarsal ligaments are three in number; they all proceed from the fibula, either to the astragalus or the os calcis. 1. The external lateral Hgament, properly so called (ligamentum fibulae medium vel per- pendiculare, m,.figs. 79 and 80), is situated beneath the sheath of the peroneus longus and brevis. It arises from the summit of the external malleolus, is directed downward and slightly backward, to be attached to the outside of the os calcis. It is rounded, and composed of parallel fibres. 2. The anterior external lateral ligament (ligamentum fibulae anterius, ?i, fig. 80) arises from the anterior edge of the external malleolus, and proceeding downward and forward, is fixed to the astragalus in front of its external malleolar facette. It is very short, and broader below than above: it forms one of the two anterior hgaments described by Bi- chat in this joint. 3. 'The posterior lateral ligament (hgamentum fibulas posterius, o,fig. 79) is very deeply seated behind; it extends from the excavation on the inside and behind the external mahcolus to the posterior border of the astragalus, immediately above the pulley of this bone. It is directed almost horizontally, or in a shght degree obliquely downward and inward, and is almost parallel to the posterior ligament of the lower peroneo-tibial ar- ticulation. It is composed of very distinct parallel fibres, which are arranged in several layers, the deepest of which are attached to the astragalus behind the facette of the ex- ternal malleolus. The posterior peroneo-astraglagean ligament is very strong. Bichat calls it the posterior ligament of the joint. The internal lateral ligament is much stronger than the three external hgaments taken together. It is composed of two very distinct layers : 1. A superficial layer, consisting of fibres stretched from the apex and the anterior and posterior borders of the internal mal- leolus to the os calcis, and the upper edge of the lower calcaneo-scaphoid ligament, which it maintains in a state of constant tension. The fibres are long and slightly divergent, but still sufficiently so to have given origin to its name of the deltoid ligament {p,figs. 79 and 80). The fibres which are most anterior pass directly forward to the neck of the astragalus, and to the scaphoid ; they form a very thin layer, which has been improper- ly cahed the anterior ligament of the ankle-joint. 2. Below the above is a deep layer of much greater extent, composed of short and strong bundles, passing downward and out- ward from the summit and sides of the internal malleolus, to the inner surface of the as- tragalus, below the articular facette.t Synovial Capsule.—The external surface of this membrane is brought into view in front and behind by removing the tendons and their sheaths ; and if the external and in- ternal lateral hgaments be divided, it wih be seen to extend into the inferior peroneo- tibial articulation. It will also be observed that it is tense at the sides, but very loose behind, and more particularly so in front. A great quantity of adipose tissue covers its external surface in these situations. Mechanism of the Ankle-joint. This articulation not only constitutes the point at which the weight of the body is * Hence, the longest diameter of the astraglagean cavity is from before backward; the longest diameter of the tibio-peroneal cavity is transversely. The extent of the movements of flexion and extension of the foot depends upon the disproportion between the antero-posterior diameter of the pulley of the astragalus and the socket of the leg. t [The author has omitted, perhaps intentionally, to give a special description of the anterior and posterior ligaments of the ankle-joint, already alluded to by him. The former extends from the anterior margin of the articular surface of the tibia to the corresponding border of the astragalus, and is called the tibio-tarsal lig- ament ; it is very thin, and covered by the tendons of the extensor muscles. The posterior can scarcely be said to exist as a distinct ligament.] Y](https://iiif.wellcomecollection.org/image/b21196801_0193.jp2/full/800%2C/0/default.jpg)
