15G 



THE ARTICULATIONS. 



pairs, extend to the summits of the wsamoids. That which is sent to each exti rnal 

 aeeanioid gives ofl', on the side of tlir tirst phalanx, a reinforcing Imml to tin- proper 



I If. W. 



aztomor of the digii The 1\\ la.-t. profound and median, <! 



into the interarticiilar notch of the IIH -t.iearpal lone, after l>eciming 

 a single fasciculus; ftfterwvdft, they pass between the two internal 

 metncarpo-phalan-eal ligaments, and scjiarat- from si'-h otl:iT in 

 passing downwards and forward.-- mi 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-phalangcal there 

 is: a proper synovial memhrane ; an interst-Nimoid ligament; an 

 inferior sesamoid ligament composed of two cross-bands ; two small 

 lateral .-e-amoid ligaments; two lateral nietacarpo-phnhingeal liga- 

 ments, attached interiorly to the fint phalanx and the sesanioids ; 

 nn anterior capsular ligament, in the centre of which is found u 

 small bony nucleus, a kind of anterior sesamoid, <>v< r which glides 

 one of the branches of the common extensor of the digits. The 

 suspensory ligament is replaced by real palmar intcrosseons muscles 

 (see the Muscles of the fore-foot}. Some fibres situated between the 

 first phalanges of the great digits in the Pig, remind one of the. 

 superior interdigital ligament of the Ox. 



In Man, the cavity in the upper extremity of the first phalanx 

 in completed by a glenoid ligament. The glenoid ligaments of tin- 

 four first digits are united to each other by a transverse ligament 

 of the metacarpus. The articulations are consolidated by two 

 lateral ligaments. The metucarpo-phalangeal articulations allow 

 flexion and extension movements, ns well as those of abduction 

 and adduction ; but the latter are limited by the lateral ligament.-. 



7. Articulation of tlie First with the Second Phalanx, or 

 First Iriterphalangeal Articulation. 



(Preparation. Remove the extensor tendon ; throw open the 

 mctacarpo-phalangeal sheath, and turn down the flexor tendons.) 



This is an imperfect hinge-joint. 



Articular surfaces. On the inferior extremity of the 

 first phalanx, there are two lateral condyles separated by a 

 groove. On the superior surface of the second phalanx, there 

 are two glenoid cavities and an antero-posterior ridge. 



The latter surface is completed behind by a glenoitlal 

 fibro-cartilage, very dense and thick, which also acts as 

 a ligament. It is attached, in one direction, to the 

 second phalanx, between the superior articular surface 

 an< ^ ^6 ^ n< ^ ^ fi xe ^ sesamoid which margins it behind ; 

 in the other, it is inserted into the first phalanx by means 

 of six fibrous bands : two superior, which embrace the 

 ARTICULA- inferior, middle, ana superficial sesamoid ligaments; two 

 ' T H'iddlo and two inferior, which extend to the sides of the 



1 3 Outer and inner i n f er i r extremity of the first phalanx. This fibro-car- 

 ' rudimentary me- tilage is moulded, in front, to the articular surface of the 

 . tatarsal bones ; 2, latter bone, and forms, by its posterior face, a gliding 

 Perforans tendon 



and its check ligament; 4, Suspensory ligament ; 5, Gliding surface, or *h<'ath for the 

 flexor tendons, formed by the posterior face of the sesnmoid bones, and intersesnmoid, 

 transverse, and annular ligaments; fi, Section of lateral sesamoid ligament; 7. J.ati-r.d 

 fasciculus of the middle inferior sesamoid ligament ; 8, Inferior sujwrficial sesnmoid 

 ligament; 9, Lateral ligament of the first intcrpli.ilMii^i al articulation; 10, S<-ctii.n 

 of the terminal branch of the jMjrforatus tendon; 11, Section of the lateral cartilage 

 of the foot; 12, Postero-inferior surface of navicular bone; 13, Section of lateral car- 

 tilage, plantar cushion, and wing of pedal bone; 14, Pcrforatus tendon; 15, Perfoiaus 

 tendon. 



POSTERIOR VIEW OF 

 THE METACARPO- 



INTER - IMIALAX- 



-.1 AL 



