OCR Text |
Show 342 MR. A. H. GARROD ON THE DEEP [Apr. 20, metatarse the flexor longus hallucis sends downwards a fibrous vinculum (V) which joins the flexor perforans digitorum tendon just before it commences to trifurcate. In all cases this vinculum is always directed downwards from the hallux-muscle to the digits-muscle, so that, when the tendon of the flexor perforans digitorum alone is pulled upon, the three anterior digits alone are flexed; but when the flexor longus hallucis is put in action, the digits as well as the hallux are simultaneously flexed. The proportion borne by this vinculum to the main tendon of the flexor longus hallucis varies considerably. In some birds it is corn- Fig. 3. Fig. 4. Tinnunculus alaudarius. in-^v IV Buceros rhinoceros. paratively feeble and insignificant; whilst in others, with but a small hallux, it is much larger than the hallucial moiety, and seems to be the main continuation outwards of the insertion of the muscle into that of the flexor perforans digitorum, the slip to the great toe being but small compared with it. In the Dorking Fowl the flexor longus hallucis tendon splits into two (after it has given off the vinculum to the flexor perforans), one resulting portion going to the normal hallux and the other to the supplementary toe, which is therefore a hallux also, as is generally supposed. This manner of distribution of the deep plantar tendons, which is that found in a great number of birds, may be summarized as follows :-The flexor perforans digitorum splits opposite the ineta- |