ARTICULATIONS OF THE ANTERIOR LIMBS. 209 



anterior extensor of the phalanges, the 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. 137). 



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

 extension and flexion. It also allows the second phalanx to pivot on the first, and 

 permits some lateral movements. 



In the Ox, Sheep, and Goat, the glenoid fibro-cartilage is confounded with the perforatus 

 tendon, and is only attached to the first pliahmx by two lateral bands. The internal lateral 

 ligament comprises two fasciculi : one, very short, which terminates in the st-coml phalanx ; 

 and another, very long, 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 inteiphalangeal 

 articuhitions of each digit are fixed by two common lateral li'j;aments which correspond exactly, 

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

 of Solipeds. 



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

 lateral ligament is, nevertheless, more like that of the Horse, in its most anterior fasciculi being 

 prolonged lo the external extremity of the navicular bone. 



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

 Interphalangeal Articulation, or Articulation op the Foot. 



Preparation. — Eemove the hoof according to the directions given hereafter, when treating of 

 the muscles of the forearm ; then the plantar cushion, the flexor tendons, and one of 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 bursae, behind 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 tliis last surface, articulate with each other by 

 arthrodia ; the navicular bone presents for tliis 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. 



Mode 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 (Fig. 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, 22 ; 135, 9).— These are two thick, 

 short, and wide fasciculi, attached by their 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 



