THE ECONOMY OF THE MUSCULAR COVERING. 75 



at pm, page 76. This muscle pulls the whole fore leg inwards keep- 

 ing it in a line with the body, so as to induce an even and regular action 

 of the limb. 



On the outside of the shoulder, and easily seen when a horse is in 

 motion, are two muscles, («") (anconfieus longus) and (/) anr.onmus 

 externum) whose office is to straighten and extend the arm. That is, to 

 bring the front limb down i)erp(Midicularly, and in a line with the lower 

 bone of the shoulder {humn-ns). Arising from the lower bone of the 

 shoulder, they arc inserted into the point of the elbows. The nmscles 

 which bend the arm ui)wards are not visible in the living animal, being 

 almost entii'cly coveied l)y those of the shoulder. 



The principal muscle of the back is the latissimus dor.n, shown on 

 page 74 as extending from the shoulder to the haunch, and on pages 

 09 and 76 at the * ; it is strongly attached to the processes of the back 

 bones and ribs, and is employed in raising the fore and hind quarters, 

 and in rearing and kicking. The portion Avhich comes nearest the surface 

 is that part which is covered by the saddle. No portion of it, however, 

 is distinctly apparent without dissection. 



IV. Muscles of the Hinder Parts. 



The muscles shown in cut 4, arc : x. Trapezius ; «, PectoraliR minor ; 

 b y Antea apinatns ; c, Postea ffpinatus; d. Teres minor -, e, Anconcmis 

 longrifi; y, AncoiuEUfi externum; g, S err ahis major •* , Latissinms dorsi ; 

 pm, Pectoralis inajor. These two latter are figured in the illustration 

 on page 76 



The Muscles of the Hind Quarters. — The illustration on page 77 

 shows all the prominent muscles of the hind quarters laid bare. Their 

 names and references are as follows: /, Glutoeus externus; m, Glutceus 

 medius; w, Triceps fem,oris -, o. Biceps; p, semi 3Ie7nbranosus, (shown 

 on page 69) ; q, Muscidus facice latce ; r. Pectus; s, Vastus externus; u, 

 Gracilis; v, Extensor pedis ; iv, Peronoeus ;x, Flexor pedis ; y, Gastroc- 

 nemii ; z, Flexor metatarsi. 



The Muscles Described. — The muscles of the hind parts are mostly 

 strongly marked, and the situation of the principal ones will be easily 

 recognized. With them will be included those concerned in or connected 

 with the motion of the hinder limbs. Among the most prominent of the 

 muscles on the front and outer parts of the haunch is that one (the Glu- 

 tceus medius) arising from the processes of several of the vertebroe of 

 the loins and from the prominent parts of the ilium, (the side bone of 

 the pelvis heretofore described) and terminating at its insertion in the 

 greyt trochanter or projection on the upper bone of the thigh (femur). 



