MUSCLES OF THE ANTEBIOB LIMBS. 



329 



Afterwards, it is inflected forwards over the sesamoid groove, and terminates by 

 two branches towards the middle of the digital region. 



Aftiirhmmts. — It takes its origin, in common with the perforans, at the 

 summit of the epitroehlea, and is inserted, 

 by the bifurcations of its tendon, into 

 the extremities of the pulley formed behind 

 the superior extremity of the second phalanx. 



Rekitiofis. — The muscular portion, 

 covered by the external and the oblicpie 

 flexors of the metacarpus, may be said to 

 be embedded in the perforans, to which it 

 adheres in the most intimate manner. The 

 tendon covers that of the latter muscle, and 

 is in turn covered by the fibrous expansions 

 of the two metacarpal and metacarpo- 

 phalangeal sheaths, which are now to be 

 described. 



Carpal shmth is the name given to a 

 very remarkable annular apparatus, formed 

 by the superficial face of the common pos- 

 terior ligament of the carpus, and by a thick 

 expansion of white fibrous tissue, together 

 constituting a perfect arch thrown across like 

 a bridge, from the pisiform bone to the inner 

 side of the carpus. This arch is continuous, 

 above, with the antibrachial aponeurosis, 

 and is prolonged, below, over the metacarpal 

 portion of the flexor tendons. An extensive 

 synovial membrane covers the internal aspect 

 of the carpal sheath, envelops the perforatus 

 and perforans in their passage through this 

 canal, ascends above the carpus, and descends 

 below the lower third of the metacarpal 

 region (Fig. 183, 4, 4), where it is insinuated 

 between the tendon of the perforans and its 

 carpal ligament. This synovial membrane 

 is strengthened in its middle portion by the 

 walls of the carpal sheath ; so that when 

 hypersecretion takes place in it, this is only 

 perceived by a swelling above the knee, ex- 

 ternally, between the posterior face of the 

 radius and the flexor muscles (Fig. 183, 8), 

 and another swelling at the tendons behind 

 the metacarpus. 



The Metacarpo-phalangeal sheath is 

 formed by the sesamoid -groove, the posterior 



TENDONS AND SYNOVIAL SHEATHS OF THE 

 ANTERIOR LIMB OF TlIK HORSE. 



M, Metcarpal bone ; El, lateral extensor of 

 the phalange> ; Ea, anterior extensor of 

 the phalanges ; Fs, tendon of the super- 

 ficial flexor of the phalanges (perfor:itus); 

 Fp, tendon of tfie deep flexor of the 

 pfialanges (perl'orans) ; Ls, suspensory 

 ligament of the fetlock. 1, Bursa for 

 the tendon of the anterior extensor of 



the metacarpus ; 2, supero-external cud- 

 de-sac of the radio-carpal bursa; 3, superior CM?-c?e-sac of the carpal i)ursa; 4, 4, inferior portion 

 of same ; 5, cul-de-sac of the capsule of the metacarpo-phalangeal articulation ; 6, 7, 8, superior, 

 middle, and inferior culs-de-sac of the sesamoid bursa; 9, inferior extremity of the same exposed 

 by excision of the reinforcing sheath of th« perforans tendon. 



