448 



THE ANATOMY OF THE HORSE 



^1! 



Flexor metacarpi externus is situated upon the postero-exteriical side of 

 the arm. Or'ujin — from a ridge on the external surface of the heel process 

 of the external condyle of the humerus. Insertion — bifid : one to the 

 supero-posterior part of the pisiform bone ; the other 

 passes through a sheath to the head of the external 

 small metacarpal bone. Action — to flex the leg. 



Flexor metacarpi medius lies on the postero- 

 internal part of the arm. Origin — bifid : one from 

 \^, l'j-5 1 1 \| the middle of a ridge extending along the internal 

 condyle of the humerus ; the other from the supero- 

 internal and posterior part of the ulna. Insertion — 

 bifid : one part to the supero-posterior part of the 

 OS pisiforme, and to the posterior annular ligament ; 

 the other to the postero-internal part of the head 

 of the inner small metacarpal bone. Action — to 

 flex the leg. 

 bN V*»| Flexor metacarpi internus is situated on the 

 postero-internal side of the arm. Origin — from a 

 ridge behind the internal condyle of the humerus. 

 Insertion — to the head of the os metacarpi parvum : 

 pi'evious to its insertion, it enters a sheath formed 

 by the annular ligament. Action — to flex the leg. 



Flexor pedis perforans et perforatus is situ- 

 ated on the posterior part of the arm. Origin — 

 common to both muscles, from a ridge on the heel 

 process of the internal condyle of the humerus. 

 Insertion — of perforatus bifid, to the external and 

 internal border of the supero-posterior part of the 

 OS coronas. Insertion — of perforans ; after receiving 

 a strong bundle of ligamentous fibres from the pos- 

 terior carpal ligament, it pierces the two divisions 

 of the flexor perforatus, opposite the pastern, and 

 .spreading out is attached to the postero-inferior part 

 of the OS pedis. Action — to flex the knee, and bend 

 the fetlock and pastern joints. 



Ulnaris accessorius is deeply seated at the pos- 

 terior part of the arm. Origin — from the whole of 

 the internal concave surface of the ulna. Insertion 

 — to the tendon of the flexor pedis, with which it 



Fig. 64.— Antero-external View of the Muscles of tue Fore-Leq. 



1. Antea spinatus. 



2. Postea sjjinatus. 



3. 4. Scapulo humeralis externus. 



5. Teres externus. 



6. Triceps extensor brachii (caput niagnum). 



7. Pectoralis transversus, divided. 



8. Triceps extensor brachii (caput medium). 



9. Flexor brachii. 



10. Extensor metacarpi magnus. 



11. Humeralis externus. 



12. Extensor pedis : a. tendon ; h. band from external lateral ligament ; c 



insertion. 



13. Extensor suffraginis. 



14. Flexor metacnriji externus. 



15. Jixtensor nietacarpi obliquus. 



