MUSCLES OP TSE ANTEBIOB LIMBS. 265 



tendon. The fleshy body, not very considerable, and flattened from 

 before backwards, extends, from the upper extremity of the radius to 

 the lower fourth of the same bone. The tendon (Fig. 119, 16'), at first 

 rounded, then flattened, reaches the gliding groove which divides the 

 external inferior tuberosity of the radius into two portions, passes to the 

 external side of the carpus, crossing the lateral ligament common to the articu- 

 lations of this region, and arrives at the anterior surface of the principal meta- 

 carpal bone, where it receives the small tendinous branch detached from the 

 anterior extensor, as well as a strong fibrous band coming from the external 

 side of the carpus (Fig. 119, 17). Afterwards, descending alongside the 

 external border of the principal tendon of its congener, and united to it by a 

 fibrous fascia, it gains the articulation of the fetlock, and expanding, ter- 

 minates at the upper extremity of the first phalanx. 



Attachments. — 1, By its muscular body, to the external tuberosity of the 

 radius, the external ligament of the elbow articulation, and to the bodies of the 

 two bones of the fore-arm — origin ; 2, By the inferior extremity of its tendon, 

 to the capsule of the metacarpo-phalangeal articulation, and in front of the 

 superior extremity of the first phalanx — termination. 



Relations. — Its muscular portion, enveloped in a special aponeurotic 

 sheath, responds : in front, to the anterior extensor of the phalanges ; behind, 

 to the external flexor of the metacarpus and the perforatus and perforans 

 muscles ; outwards, to the antihrachial aponeurosis. The tendon, surrounded 

 by a vaginal synovial sheath, in passing over the carpus, covers, beyond the 

 knee, the anterior aspect of the metacarpus, and the anterior ligament of the 

 metacarpo-phalangeal articulation, over which it glides by means of a small 

 vesicular synovial bursa. It is covered by a slight fibrous fascia, which 

 separates it from the skin, and which is also spread over the tendon of the 

 anterior extensor. 



Action. — This muscle is an extensor of the digit, and also concurs in the 

 extension of the entire foot on the fore-arm. / 



B. Posterior Antihrachial Begion. 



This is composed of five flexor muscles grouped vertically behind the 

 bones of the fore-arm. Three are situated superficially, and act on the whole 

 foot ; these are the external flexor, oblique flexor, and the internal flexor of 

 the metacarpus. The other two, fixed to the digit by their inferior extremity, 

 and covered by the preceding, are designated the superficial and deep flexors 

 of the phalanges. 



1. External Flexor of the Metacarpus, or Posterior Ulnaris.^ (l^ig- H^i 18.) 



Synonyms. — Epioondylo-supercarpeus — Girard. (^Flexor metaearpi externui — 

 Percivall. Humero-supercarpeue externus — Leyh.) 



Situation. — The external flexor of the metacarpus is situated at the ex- 

 ternal side of the fore-arm, between the lateral extensor of the phalanges 

 and the oblique flexor. 



Form — Structure — Attachments. — This muscle is elongated from above to 

 below, flattened from one side to the other, thick in its middle part, and 

 intersected by very strong aponeurotic bands. It commences on the summit 



• It is known that the bony eminences, hitherto termed in veterinary anatomy 

 " epitroohlea " and " epicondyle," correspond ; the first, to the epicondyle of Man, the second, 

 to the cpitrochlea. It need excite no surprise, therefore, to see the denominations given 

 by Girard to the muscles of the posterior antihrachial region changed as above. 



