ARTICULATI0S8 OF THE ANTERIOR LIMBS. 209 



anterior extensor of the phalanges, tlie lateral ligaments, and the glenoid fibro- 

 cartilage. Behind, it forms a cul-de-sac, which extends between the latter and the 

 posterior face of the first phalanx (Fig. 187). 



Movements. — This imperfect hinge is the seat of two principal movements : 

 extension a.udfiexion. It also allows the second phalanx to pivot on the tirat, and 

 permits some lateral movements. 



In the Ox, Sheep, and Goat, the glenoid fibro-ciirtilago is confounded with tlie perforatua 

 tendon, and is only attachi d to the first piialanx by two lateral bands. Tlie internal lateral 

 ligament comprist-a two fasciculi : one, very atiort, which terminates in the second phalanx ; 

 and another, vt- ry lon;r, descending to the internal face of the third phalanx. The external is 

 very thin, and is also prolonged to the terminal phalanx ; so that the two last interphalangeal 

 articnltions of eich digit are fixed by two common lati-ral ligaments which correspond exactly, 

 by their position and inferior attachments, to the anterior lateral ligaments of the pedal joint 

 of Solipeds. 



In ti e Dog and Cat, the glenoid cartilage, also confounded by its posterior face with the 

 perforatus tendon, only adheres to the first phalanx by some cellular bands. The two lateral 

 ligaments pass from the inferior extremity of the first phalanx to the superior extremity of the 

 second. 



In the Pig, jthere is somewhat the same arrangement as in Carnivora. The external 

 latenil ligament is, nevertheless, more like that of the Horse, in its most anterior fascici li being 

 proloiigtd 10 the external extremity of the navicular bone. 



8. Articulation of the Second Phalanx with the Third, Second 

 Interphalangeal Articulation, or Articulation of the Foot. 



Preparation. — Remove the hoof according to the directions given hereafter, wlieu treating of 

 the Tnnscles of the forearm; then tlie plantar cushion, the flexor tendons, and one uf the lateral 

 cartilages. A section like that shown in Fig. 137 is useful to show the relations between the 

 synovial capsule of this joint and the bursas, beldnd the second phalanx. 



To form this imperfect hinge-joint, the second phalanx is opposed to the tliird, 

 and to the navicular bone. 



Articular surfaces.- — On the inferior face of the second phalanx there are two 

 lateral condyles and a median groove. On the superior face of the third phalanx 

 and the navicular bone, are two glenoid cavities separated by an antero-posterior 

 ridge. The two bones which form this last surface, articulate with each other by 

 arthrodia ; the navicular bone presents for this purpose an elongated facet on its 

 anterior border ; the os pedis also offers an analogous facet on the posterior contour 

 of the principal articular surface. 



Jfod^' of union. — Five ligaments : a single interosseous one, which joins the 

 navicular to the pedal bone ; and four lateral bones, distinguished as anterior and 

 posterior. 



a. Interosseous ligament {Yig. 136, 2). — This is formed of very short fibres, 

 which are inserted, behind, into the anterior groove of the navicular bone ; and 

 in front, into the posterior border and inferior face of the third phalanx. This 

 ligament is lined, on its superior surface, by the synovial membrane, and on its 

 inferior face is covered by the navicular sheath. 



h. Anterior lateral ligaments (Figs. 132, 2i ; 135, 9).— These are two thick, 

 short, and wide fasciculi, attached by theii* superior extremities to the lateral 

 imprints of the second phalanx, and by their inferior extremities into the two 

 cavities at the base of the pyramidal eminence of the os pedis. Each ligament is 

 partly covered by the complementary fibro-cartilage of that bone, and appears to 

 form a portion of it. Its anterior border is continuous with the common extensor 



