400 THE HORSE. 
MUSCLES OF THE ARM AND FORE LEG. 
EXTENSOR METACARPI MAGNUS is situated on the anterior part of the 
arm. Origin—from a ridge situated at the antero-external part of the 
humerus, and also from a depression just 
above the external condyle of the humerus. 
Insertion—to the antero-superior part of the 
os metacarpi magnum. Action—to extend 
the leg. 
EXTENSOR PEDIS is situated upon the 
antero-external part of the arm. Ovigin— 
from the fore part of the external condyle of 
the humerus, and from a ridge just superiorly 
placed to it; from the outer part of the head, 
and from the anterior and supero-external 
part of the body of the radius; and from 
the capsular ligament of the elbow joint. 
Insertion—to the coronal process of the os 
pedis, adhering firmly to the capsular liga- 
ment of the fetlock joint. Action—to extend 
the knee, metacarpals, and pasterns, and to 
elevate the toe. 
FLEXOR METACARPI EXTERNUS Is situated 
upon the postero-external side of the arm. 
Origin—from a ridge on the external surface 
of the heel process of the external condyle of 
the humerus. Jnsertion—bifid : one to the 
supero-posterior part of the pisiform bone ; 
the otherpasses through a sheath to the head 
of the externalsmall metacarpal bone. Action 
—to flex the leg. 
FLEXOR METACARPI MEDIUS lies on the 
postero-internal part of the arm. Origin— 
bifid: one from the middle of a ridge ex- 
tending along the internal condyle of the 
humerus; the other from the supero-internal 
and posterior part of the ulna. Inserticon— 
bifid: one part to the supero-posterior part 
of the os pisiforme, and to the posterior 
annular ligament ; the other to the postero- 
Fic. 5.—ANTERO-EXTERNAL VIEW OF THE MUSCLES OF THE 
Fore Lea. 
1. Antea spinatus. 
2. Postea spinatus. 
3, 4. Scapulo humeralis externus. 
5. Teres externus. 
6. Triceps extensor brachii (caput magnum). 
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; b. band from external lateral 
ligament ; c. insertion. 
3. Extensor suffraginis. 
14. Flexor metacarpi externus. 
15. Extensor metacarpi obliquus, 
