ARTICULATIONS OF THE ANTERIOR LIMBS. 



207 



with two small interosseous muscles, the lateral metacarpal bones, and the digital 

 vessels and nerves. 



Synovial membrane. — Tliis membrane is prolonged as a cul-de-sac between the 

 terminal branches of the preceding ligament. It is the distension of this sac 

 which causes the articular swellings vulgarly designated 

 " windgalls." Fig. 133. 



Movements. — The metacarpo-phalangeal articulation 

 permits the extension and flexion of the digit, and some 

 slight lateral motion when the movable osseous segment 

 is carried to the limits of flexion. 



In the Ox, Sheep, and G-oat, this articulation constitutes a 

 dotible hinge, which resembles the simple ginglymus of Solipeds. 



They have three intersesamoid ligaments : two lateral, to unite 

 the large sesamoids of each digit ; and a median, which unites 

 the interual sesamoids. The inferior sesamoidean ligamentous 

 apparatus is far from showing the same degree of development 

 as in the Horse. It is reduced for each digit to four small bands, 

 which remind one very much of the deep ligament of the latter 

 animal, as it has been described by Rigot : two lateral bands pass 

 directly from the sesamoids to the upper extremity of the first 

 phalanx ; the other two, situated between the first, intercross 

 and are confounded with the latter by their extremities. A lateral 

 tesamoid ligament unites the first phalanx to the exterual sesamoid. 



For each digit there are two lateral metacarpo-phalangeal 

 ligaments— a,n external, analogous to that of the Horse, but less 

 complicated, is attached by its inferior extremity to the first 

 phalanx only ; the other, internal, fixed superiorly in the bottom 

 of the inter-articular notch of the metacarpal bone, is inserted 

 into the inner face of the first phalanx in mixing its fibres with 

 those of the superior interdigital ligament. This latter is situated 

 between the two first phalanges, and is composed of short, inter- 

 crossed fibres, attached to the imprints which in part cover the 

 internal face of the two first phalangeal bones. In the Sheep 

 there are only traces of this interdigital ligament, and each internal 

 metacarpal-phalangeal gives rise, near its phalangeal insertion, to 

 a fibrous branch which is directed backwards from the interdigital 

 Bpace, and is terminated in the bone of the ergot (or posterior 

 rudimentary digit), which it sustains. The anterior or capsular 

 ligament, single as in Solipeds, unites the two external lateralliga- 

 ments. The suspensory ligament, single superiorly, is divided inferiorly into eight branches, two 

 of which are joined to the periuratus tendon, to form with it the double ring through which the 

 two branches of the perforans pass. Four other branches, in pairs, extend to the summits of 

 the sesamoids. That which is sent to each external sesamoid gives off, on the side of the first 

 phalanx, a reinforcing band to the proper extensor of the digit. The two last, profound and 

 median, descend into the inter-articular notch of the metacarpal bone, after becoming a single 

 fasciculus ; afterwards, they pass between two internal metacarpo-phalangt-al ligaments, and 

 separate from each other in passing downwards and forwards on the inner side of the first 

 phalanx, to join the proper extensor tendon of each digit. 



In the Pig, Dog, and Cat, for each metacarpo-phalangeal there is: a proper synovial 

 membrane; an intersesamoid ligament; an inferior sesamoid ligament composed of two cross- 

 bands; two small lateral sesamoid ligaments; two lateral metacarpo-phalangeal ligaments, 

 attached inferiorly to the first phalanx and the sesamoids ; an anterior capsular ligament, in 

 the centre of which is found a small bony nucleus — a kind of anterior sesamoid— over which 

 glides one of the branches of the common extensor of the digits. The suspensory ligament is 

 replaced by real palmar interosseous muscles (see the Muscles of the Anterior Foot). Some 

 fibres situated between the first phalanges in the great digits of the Pig, resemble the superior 

 interdigital ligament of the Ox. 



In Man, the cavity in the upper extremity of the first phalanx is completed by a glenoid 



SECTION OF THE INFERIOR 

 ROW OF CARPAL BONES, 

 THE METACARPAL, AND 

 THE SUSPENSORY LIGA- 

 MENT OF THE FETLOCK. 



1, Os magnum ; 2, common 

 posterior ligament of the 

 carpus ; 3, stay, or band 

 for tlie perforans tendon , 

 4, suspensory ligament of 

 the fetlock ; 5, its super- 

 ficial layer ; 6, its deep 

 fasciculus ; 7, principal 

 metacarpal bone. 



