MUSCULAR SYSTEM. 141 



Action. — To extend the fopt and pasterns; and at the same 

 time to assist in the extension of the knee. 



EXTENSOR suFFRAGiNis. — RadiciUs-prephalangais. 



Situation. — Postero-external part of the arm. 



Form. — Narrow; thin; elongated. 



Attachment. — Superiorly, to the postero-external and superior 

 parts of the radius, and to the posterior (sharpened) border of 

 the ulna : inferiorly, to the supero-anterior part of the os suffra- 

 ginis, adhering to the capsular ligament of the fetlock joint. 



lielations — Anteriorly, with the preceding muscle and the 

 extensor obliquus ; posteriorly, with the flexores, perforans ot 

 perforatus ; internally, with the ulna and radius; exteinally, with 

 the faschia and skin. 



Direction. — Half-penniform : from above downwards, and 

 from behind forwards. 



Structure. — It may be denominated a muscular slip, whose 

 superior attachments are tendinous and fleshy ; anterior part apo- 

 neurotic; and posterior partly tendinous, but mostly flesliy. 

 A little higher than the knee, it detaches a slender flattened ten- 

 don, which passes through a sheath, under the external lateral 

 ligament, and then inclines forwards, and unites about half-way 

 down the leg with the long extensor ligament. 



Action. — To assist in extending the fetlock, and also, in some 

 degree, the knee ; and to tighten the extensor ligament. 



EXTENSOR METACARFI OBLIQUUS V E L PARVUS. RacUaHs- 



metacarpeus obliquus. 



Situation. — Deep-seated : infero-anterior parts of the arm. 



Figure. — Triangular; flattened; somewhat curved. 



Attachment.— ^upe\'\ov\y, to the outer and infero-anterior parts 

 of the body of the radius : inferiorly, to the supero-anterior part 

 of the OS metacarpi internum. 



Relations. — Anteriorly, with the extensor pedis, faschia and 

 skin ; posteriorly, with the radius, extensor metacarpi, and knee 

 joint: to the outer side, with the preceding muscle; to the inner, 

 with the extensor metacarpi. 



Direction, — Oblique and inclined to a curve, from above 

 downwards, and from behind forwards. 



Structure. — It consists of a small fleshy slip beginning in a 

 pyramidal point, but growing broader as it descends, and ending 

 in a tendon which crosses under the extensor pedis, but over 

 the extensor metacarpi. Its superior attachments are principally 

 fleshy ; its belly is palish, and aponeurotic upon its front surface. 



