290 Rev. S. Haughton on the Muscular 



belonging to the various muscles thus mark out fixed lines 

 round which the planes of muscular momentum must turn in 

 every conceivable position of the joint. 



If we compare together the positions of these fixed lines in 

 the pelvic and scapular joints, we may readily obtain relations 

 between the muscles of the hind and fore limb that would 

 escape notice unless so examined, and which seem to possess 

 much interest. 



Let us commence with the pelvic joint (PI. X. fig, 1), and 

 take for the zero of our circle described round the centre of the 

 joint the plane of the rectus femoris, tensor vaginas femoris, 

 and sartorius, which corresponds with the plane of flexion of 

 the knee-joint. 



Following from right to left (on left side of pelvis) the order 

 of muscles, we obtain the following table : — 



Pelvic Joint. 



Weight. Azimuth. 



{Sartorius 

 Rectus femoris \ 1-25 oz. 0° 



Tensor vaginse femoris 



, } 



3_ r Marsupialis externus 1 ^^^^ ^^o 



[ Marsupialis internus J 

 r Gracilis ] 



4. \ Pectineus I 3-22 oz. 106° 



[ Adductor brevis J 



5. j \f^'^^' f^^'^^'^ I 1-79 oz. 125- 



[ Adductor longus J 



6. Obturator externus 0-97 oz. 149° 



^■{IZL ^ 4-87 oz. 23" 



J Quadratus femoris 1 , ^,oa -i njc 



\ Extensor femoris caudalis J 



r Biceps femoris 



8. \ Semitendinosus ^ 4-49 oz. 217° 



[ Semimembranosus 

 f Glutaeus maximus 1 



9. \ Glutaeus medius l 4-09 oz. 266° 



[ Agitator caudse J 



Total.. 38-62 oz. av. 



In the preceding table I have reckoned gracilis in the same 

 azimuth with pectineus and adductor brevis, because the re- 

 sultant of its two heads lies in this line. 



The fixed lines of the muscles of the shoulder-joint, com- 

 mencing with the triceps longus, which is in the plane of 

 motion of the elbow-joint, from left to right (on left side of 

 shoulder), may be arranged as follows : — 



