172 THE ARTICULATIONS. 



up with the internal and superficial tibio-tarsal ligaments in diverging down- 

 wards to the scaphoides, the great cuneiform bone, and the upper extremity 

 of the principal metatarsal bone. 



4. The posterior tarso-metaiarsal ligament is a vast, very strong, and very 

 complicated fibrous arrangement, which binds, posteriorly, all the tarsal 

 bones, and also fixes them to the three portions of the metatarsus. This 

 band, which is crossed by several tendons and by the artery and vein lodged 

 in the cuboido-scaphoido-cunean canal, is continued below by the tarsal 

 stay of the perforans tendon. It therefore closely resembles the posterior 

 carpal ligament. Its posterior face is covered by the tendinous synovial 

 membrane lining the tarsal sheath for the passage of the perforans tendons. 

 It is confounded, on its sides, with the calcaneo-metatarsal, and the internal 

 and superficial tibio-tarsal ligaments. 



5. An interosseous ligament, attached to the four bones composing this 

 articulation. 



It is provided with a particular synovial membrane which always 

 communicates, in front, with the tibio-tarsal capsule. This membrane is 

 prolonged, superiorly, between the calcis and astragalus, to lubrify two of 

 the facets by which these bones come into contact ; and, iu addition, it 

 descends between the cuboid and scaphoid bones to form a third pro- 

 longation for the anterior cuboido-scaphoid arthrodia. 



Movements almost null. 



Taeso-metataesal Articulation. — This joint, formed by the meeting of 

 the three tarsal bones — the cuboid and the two cuneiforms — with the three 

 bones of the metatarsus, is fixed by the lateral superficial ligaments of the 

 tibio-tarsal articulation, the calcaneo-metatarsal ligament, those which have 

 been named the astragalo-metatarsal and tarso-metatarsal, and by a strong 

 interosseous ligament which naturally forms three fasciculi. 



The synovial membrane proper to this joint ascends into the small 

 anterior cuboido-cunean arthrodia, and into that which unites the two 

 cuneiform bones ; it descends to the intermetatarsal articulations. 



Movements nearly null. 



In all the domesticated animals except Solipeds, the tarsal ai'ticnlations offer some diffe- 

 rential peculiarities whose study is without interest, as it is without utility. It is only 

 neci^ssary to remark that the immobility of the tarsal joints, properly called, is less 

 absolute than in Solipeds, owing to the peculiar configuration of the articular surfaces of 

 some of the bones composing them. 'I'hus, in the Ox, Sheep, Goat, and Pig, the calels 

 is joined to the astragalus by a real trochlear articulation, and the latter bone is united 

 to the scaphoid by a diarthrodinl joint of the same kind ; a mode of articulation much 

 more favourable to motion than that of the planiform diarthrodial joint. In the Dog and 

 Cat, the same result is obtained by the reception of the head of the astragalus into the 

 superior cavity ofxthe soaphoids. 



In Buminants and the Pig, it is also observed that the tibio-tarsal articulation is 

 formed by the tibia and fibula in the one direction, and by the astragalus and os calcis 

 in the other. 



CHAPTEE III. 



OF THE AETICDLATIONS IN BIRDS. 



The study of the articulations in birds will only arrest us for a few moments, as it 

 will be confined to some remarks on the intervertebral oocigito-atloid and temporo- 

 maxillary joints, the only ones exhibiting a special conformation worthy of attention. 



Intervertebral articulations. — The great mobility of the neck of birds is not only due 

 to tlie fact of its length, relatively considered, but also to the peculiar manner in which 

 the vertebrae of this portion of the spinal stalk are articulated. It will be remarked that 



