158 THE CAT. [CHAP. v. 



is ultimately inserted into the ligament of the patella and internal 

 tuberosity of the tibia. Some of its muscular fibres extend down to 

 the tibia below its inner tuberosity. 



The gracilis is a wide, flat, muscular sheet, which arises by 

 tendinous fascia from beneath the symphysis pubis, and is similarly 

 inserted into the inner side of the tibia, its broad insertion being 

 overlapped by the sartorius. Like the preceding muscle it is a 

 flexor of the leg on the thigh. 



Semi- tend inostts. This is a long, subcylindrical muscle, which arises 

 by tendon and fascia from the tuberosity of the ischium, beneath 

 and a little behind the origin of the biceps femoris. It is inserted 

 partly into the tendinous sheath of fascia which goes to the inner 

 side of the tibia, and partly, by a very strong tendon, into the front 

 of the tibia, about half an inch below the patella (Fig. 84, T). 



The semi-membmnosiis is very thick and fleshy, and more or less 

 double. It arises from the tuberosity of the ischium, and from the 

 ramus of the ischium below the tuberosity down to the symphysis. 

 It is much united in its course and insertion with the adductor. It 

 is inserted into the inner condyle of the femur and above it up to the 

 insertion of the adductor, and also by a strong tendon (which passes 

 beneath the internal lateral ligament of the knee) into the internal 

 tuberosity of the tibia (Fig. 74, sm). The part with the latter insertion 

 arises within the origin of the other part, the muscle being near its 

 origin folded on itself, with the opening of the fold forwards. The 

 two parts are entirely separable for the last inch of their course. The 

 part inserted into the inner condyle is closely connected with the 

 internal head of the gastrocnemius. 



Biceps femoris. This is an enormous sheet of muscle, the fibres of 

 which expand in a fan-like manner (Fig. 82, _Z?). It arises (by muscle 

 and strong tendon) from the tuberosity of the ischium, somewhat 

 between the origin of the semi-tendinosus and semi-membranosus, but 

 anterior to both. It is inserted by a tendinous fascia into the outer 

 side of the leg from the top of the knee-joint nearly to the heel, but 

 it is especially inserted into the outer tuberosity of the tibia. 



The three muscles last described are called the hamstring muscles, 

 and are powerful flexors of the leg. 



Tenuissimus (Fig. 83). This most delicate muscle arises from the 

 caudal vertebra) at the front end of the second part of the gluteus 

 maximus, with which it is intimately united. Passing down beneath 

 the gluteus maximus and inside the biceps, it ends by blending with 

 the inner surface of the latter muscle close to the anterior end of its 

 inferior margin. 



The quadriceps extensor, or great extensor of the leg, consists of 

 four parts, which have a common insertion into the tendon of the 

 patella, and, through it, into the tuberosity of the tibia. 



The first part is the rectus fcmoris, and arises from the hinder 

 part of the ventral margin of the ilium, and, by a tendon, from the 

 antero -superior margin of the acetabulum. 



The second part, or vastus extermis, is of enormous size, wrapping 



