l.-.j Till- ARTICULATIONS. 



particular fasciculi : two lateral (seen on each wide of the superficial liga- 

 im nt in Fitf. Nl>, 8), and a median which has been generally confounded 

 with the superficial ligament, although it is clearly distin,Mii-ln-.l limn it 

 by its inferior insertion. Fixed in common to the posterior imprints of the 

 first phalanx, these three fasciculi diverge in ascending to the base of tho 

 sesamoids, where they have their upper insertion. 



The deep ligament is constituted by two small bands concealed beneath 

 tho middle ligament. Thin, short, flattened before and behind, und inter- 

 crossed, these bands arc fixed to tho base of the sesamoids in one direction, 

 and in tho other to the superior extremity of the first phalanx, near tho 

 margin of its articular surface. This ligament is lined on its anterior face 

 by the synovial membrane of tho articulation. 1 



c. The lateral sesamoid ligaments are two thin layers extending from tho 

 external face of each sesarnoid to tho tubercle of insertion on tho side of 

 the superior extremity of the first phalanx. They ore covered by the digital 

 vessels and nerves, by the fibrous stay detached from the suspensory liga- 

 ment to the anterior extensor tendon of the phalanges, and by the superficial 

 fasciculus of the lateral metacarpo-phalaugeal ligament ; they are covered by 

 synovial membrane on their internal face. 



B. The ligaments destined to unite the two articular surfaces of the meta- 

 carpo-phalangeal joint ore four : two lateral, one anterior, and one posterior. 



a. Each lateral ligament comprises two fasciculi, a superficial and a 

 deep, firmly united by their adjacent faces. The superficial fasciculus 

 commences on the button of tho lateral metacarpal bone, attaches itself to 

 the median motacarpal, and descends vertically to terminate at the superior 

 extremity of the first phalanx. It covers tho phalangeal insertion of the 

 lateral sesamoid ligament and the deep fasciculus. Tho latter, attached 

 superiorly in the lateral excavation of tho inferior extremity of the principal 

 metacarpal, radiates as it roaches the sesamoid and the superior extremity 

 of the first phalanx, where it is fixed by mixing its fibres with those of tho 

 lateral sesamoid ligament. The inner face of this fasciculus is lined by the 

 articular synovial membrane. 



6. The anterior ligament belongs to the class of capsular ligaments. It 

 is a very resisting membraniform expansion which envelops the anterior face 

 of the articulation. Attached by its upper border to the anterior margin of 

 the metacarpal surface, and by its inferior border to the first phalanx, this 

 expansion is confounded at its sides with the lateral ligaments. It is covered 

 by tho extensor tendons of the phalanges, which glide on its surface by means 

 of small serous sacs. Its internal face adheres throughout its whole extent 

 to the synovial capsule. 



c. The posterior ligament? very appropiatcly named the suspensory ligaim nl 

 of the fetlock (Figs. 88 ; 89, 4), is a long and powerful brace, composed of white 

 fibrous tissue, and often containing fasciculi of fleshy fibres in its texture. 

 Lodged behind tho median motacarpal, and between the two lateral mcta- 

 carpal bones, this brace is quite thin at its origin, but it soon becomes 

 enlarged, and preserves its great thickness to the extent of its upper fourth. 

 Examined in section, it appears to be formed of two superposed portions which 

 are closely adherent to each other. Tho superficial portion, tho thinnest, 

 commences by three small branches, which arc fixed to tho first and socond 



1 The two bands described by Rigot as forming port of this ligament, belong to the 

 lateral fasciculi of the middle ligament. 



3 \t corrcHixmds to the two muscles which, in MAN, lie alongside the intcrosseous 

 in. lu<-arj>;il muscles. See the Muscles of tlie fool. 



