ARTICULATIONS OF THE POSTM!!"!! I.IMi:>. l.V. 



becoming confounded with the perforans tendon, the plantar cushion, nnd the kera- 



IIS niellll-nille. 



In tin- /'/;/. tor tin- maintenance of the second iuterphnlangcal articulation, tin n- 

 are: 1, Two lateral ligaim-nts, carried from the lateral faces of the second phalanx to 

 tin- external and internal fa<'i-s of the tliird; 2, A third ligament, exactly resembling one 

 of the jiosterior lateral ligaments of the pedal articulation of the Horse; this ligament 

 descend* from the inferior extremity of the first phalanx to the internal ( -xtn -mity of the 

 n.i\ ii-iihir bone. Its analogue of the inner side appears to be altogether aK- nt : l,nt 

 in the large digits there is an anterior yellow elastic ligament like thut of Ruminants. 



In the Dog, the two last phalanges are united 1>\ two lateral ligaments, very simply 

 arranged. A third ligament, funned of elastic tis>iie. divided into two lateral (Nations, 

 ami .-ituated in front of the articulation, plays the part of a spring, which mechanically 

 produces the retraction of the claw when the flexor muscles cease to contract. In the 

 t'nl. this yellow ligament is very strong; and this animal also exhibits a very striking 

 iibliijuity of the articular pulleys by which the two phalanges correspond: an arrange- 

 ment which jR-nnits the claw to be lodged between two digits when they ure raised, ami 

 thus favour its retraction. ^ 



The second interphalangeal articulation of the Dog and Cat is also distingui.-ln d 

 by another essential arrangement. The articular surface of the third phalanx is com- 

 1 by a glenoid fibrc~cartilage analogous to that of the first articulation, but much 

 thicker. This h'bro-cartilage {see MUSCLES OF THE HAND) is fixed into the posterior 

 projection of the third phalanx, and serves, by its inferior face, as a pulley for the per- 

 fonms tt-ndon and, with the projection just named, plays the part of the navicular bone 

 in other annual-. 



The interphalangeal articulations of Man are formed on the eame plan as the 

 metacarpo-phalangeul articulations. They are consolidated by a glenoid and lateral 

 ligaments, and possess only the two movements of flexion and extension. 



ARTICLE V. ARTICULATIONS OF TUB POSTERIOR LIMBS. 



1. Articulations of the Pelvis. 



(Preparation. These ligaments are all exposed to view by carefully removing the soft 

 parts conne'-ti d with the sacrum and coxa).) 



A. SACUO-ILIAC ARTICULATION (Fig. 90). This is a pair articulation 

 which establishes the union of the posterior limb with the spino, and is 

 formed by the sacrum and coxa. It belongs to the arthrodial class. 



Articular surfaces. On the sacrum, the irregular diarthrodial facet 

 named the " auricular," cut on the sides and near the base of the bone. For 

 the coxa, the analogous facet on the internal face of the ilium. 



Mode of union. By four ligaments, which, after the example of Rigot, 

 we will name sacro-iliac, superior ilio-sacral, inferior ilio- sacral, and the 

 sacro-lxflinfir. 



a. Sacro-iliac liyament. This is composed of thick fibrous fasciculi, 

 which envelope the whole articulation in being firmly attached by their 

 extremities to the imprints around the diarthrodial facets. The inferior 

 moiety of this ligament is covered by the psoas-iliacus (iliacus) muscle. Its 

 IK >>tcrior half 1 is much stronger, is hidden by the ilium, and gives attach- 

 ment to the ilio-spinalis (longissimus dorsi) muscle. 



b. Superior Clio-sacral li</<nn< nt. A thick and short funiclo which, 

 rising from the internal angle of the ilium, is carried backwards to bo fixed 

 to the sacral spine, where its fibres are confounded with those of the MIJKT- 

 spinous dorso-lumbar ligament. 



<. Inferior ilio-sacral ligament. This is a very resisting, triangular, 

 membranous band, formed of parallel fibres passing obliquely downwards 

 and backwards. It is attached, by its anterior margin, to the upper halt < f 



1 It represents the itero**fou tacrili'.ir li,jament of Man. Tho inferior half ei>rr - 

 -p., mis to tlie anterior ocro-t/i<i/- li^um nt. 



