OCR Text |
Show 1890.] HELODERMA SUSPECTUM. 185 other, more cord-like, extends down the leg, where it is in relation with the soleus muscle. 88. The Rectus femoris arises by two thoroughly distinct heads ; one of these, and by far the slenderer, has its origin upon the pelvis, just in front of the acetabulum, the tendon in this case being flat and of some length. At about the middle of the thigh this head, which has now become muscular, merges with the larger division of the rectus, although both it and its tendon can be easily traced as far as the patella. The larger head of the rectus arises from the pelvis immediately over the acetabulum by a broad tendinous origin.. Soon becoming fleshy, the muscle passes directly down the dorsal aspect of the thigh, aud, by a tendino-aponeurotic expansion, is inserted into the top of the patella, from which it is in turn reinserted into the outer surface of the head of the tibia, through the intervention of the ligamentum patellae. 89. Gluteus maximus.-Although here a distinct muscle, it has pratically the same origin and insertion as the larger of the two heads of the rectus femoris, with which it is almost indistiuguishably fused. It assists in covering the dorso-superficial aspect of the thigh posterior to the latter, and in its action aids the rectus in extending the leg upon the thigh, as in all Vertebrata where it is present. Upon its underside, this muscle, in the lower part of its course, exhibits a strong tendency to blend with the vastus externus, which lies beneath it. 90. Pectineus.-By transversely dividing at their middles the rectus femoris and the gluteus maximus and reflecting the mesial stump, we bring to view the more deeply situate muscles of the thigh, and the present one can be easily examined. It is here found to be of a triangular form, and arises from the ilium posterior to and above the acetabulum ; it is also attached to the nether side of the tendon of the gluteus maximus, and mere internally to the pubo-ischiadic ligament. Largely carneous in its organization, its fibres pass downwards and forwards to the shaft of the femur, where they are inserted upon a longitudinal line extending down the middle third of the same at its postero-ventral aspect. 91. The Biceps femoris is a perfectly straight, subcylindrical muscle of nearly uniform calibre throughout its length. Its single and only head arises from the outer surface of the ilium, at its anterior third, just behind and above the acetabulum, but posterior to the origin of the pectineus. It is inserted on to the outer aspect of the shaft of the fibula immediately below the head of the bone. At its origin it is fleshy, but it is inserted by a comparatively strong tendon, as is quite commonly the case in Lizards. Sanders found this muscle arising from the posterior end of the ilium in Liolepis ; while Hoffmann, from his description of this muscle, seems to think that this is the onlv origin it can have (Bronn's ' Klassen,' loc. cit. pp. 644, 645). 92. Adductor brevis.-This is one of the smallest and at the same time one of the most deeply situated muscles of the thigh. In some respects it seems to correspond with either one or the other of the |