OF COLYMBUS TORQUATUS. 169 



femur, yet its action must be powerful, from the amount of contractile fibre it contains 

 and from the great increase of leverage obtained from the projecting spine of the tibia. 



Vasti? On either side of the preceding lies a smaller muscle, having its origin from 

 the femur near its head. They proceed over the femoral condyles to be inserted respec- 

 tively into the inner side of the head of the tibia, and into the head of the fibula close to 

 the articulating surface. 



From the origin and position of these muscles, they seem to represent the vasti ; but by 

 a slight variation in their insertion, their function is entirely changed. They can exert 

 but very slight, if any, action as extensors of the leg. They are rotators of the leg 

 upon the thigh. The internal one acts conjointly with the sartorius; while the external 

 one is intimately blended with the tendon of the broad fan-shaped muscle, above described, 

 and referred to the rectus femoris. 



It will thus be seen, that of the four muscles which in the human species conjoin to form 

 a " quadriceps extensor cruris," only one, the cruraeus, is here left as a proper extensor. The 

 rectus joins the vastus externus, and both are together inserted into the head of the fibula, 

 to act rather as external rotators ; while the vastus internus forms an internal rotator, in 

 which action it is assisted by the sartorius. 



The " pubo-femoral " muscles, — the proper adductors of the thigh, — are represented by 

 abroad plane of muscular fibre, which arises from the whole length of the horizontal ramus 

 of the pubes, and from a considerable portion of the obturator fascia. From this extensive 

 origin the muscle converges as a thin flat plane, to be inserted by a broad tendon into the 

 lower half of the femur. I was not able to divide these fibres into distinct muscles. 



A large, somewhat flattened muscle arises from near the tuber ischii, and from the sides 

 of the sacrum nearly as far as the femur ; also from the surface of the pelvis not occupied 

 by the gluteus maximus, which it overlies, and proceeds obliquely upwards and outwards, 

 to be inserted into a tubercle on the inner and posterior aspect of the femur, a little below 

 its middle. On the external surface, the tendinous portion of the muscle extends to within 

 two inches of its origin ; but on the internal aspect the muscle is fleshy, nearly to its point 

 of insertion. 



The first of the two preceding muscles is of course homologous with our adductors, 

 and the latter would seem from its insertion to belong to the same class. But however 

 this may be, the shape of the pelvis, and the relative position of the femur are such, that 

 any action they may have as adductors can be but slight, and must be greatly overbal- 

 anced by their more energetic action as extensores femoris. 



In connection with the muscle last described, there is to be noticed one belonging to 

 quite a different set, viz. the " femoro-coccygeal." This is a small, narrow, ribbon-like muscle 

 arising from the base of the coccygeal vomer. It proceeds forwards, fleshy, for two and a 

 half inches, changes suddenly to a small rounded tendon, which lies along the outside of 

 the tendon of the muscle last described. They soon become intimately blended together, 

 and proceed as one tendon to their insertion into the femur. 



There is thus a strong " guy " proceeding on each side of the pelvis from the femur to 

 the coccyx, reminding one irresistibly of the tiller-ropes of a boat's rudder. Acting to- 

 gether they serve to steady the tail ; more strongly contracting, they draw it downwards ; 

 while either acting alone draws the tail obliquely downwards and to the corresponding 

 side. 



Semi-tendiiiosus. Arises from the tuber ischii, being at its origin intimately blended with 



