A Study on the Movement Pattern of Four Limbs in Walking [1

Abstract

1. The author using 8mm cinecamera (48 or 64 frames per second) observed the movement sequence of four limbs of many mammals while they were walk-ing on all fours. In the slow motion picture, protraction or retraction of each limb was confirmed and the movement sequence of all four limbs was combined. The walking type of many mammals commonly seen in the zoo was "backward cross type" as shown in Fig. 1, but many monkeys showed completely different walking type, "forward cross type", as shown in Fig. 2. These figures show that each limb moves one after another according to the arrows (cf. IWAMOTO & TOMITA 1966).Some examples of walking monkeys are given in Fig. 3-Fig. 6. Names of monkeys which were observed walking with "forward cross type" are shown in Table 1.The prevalence of "forward cross type" in the primates and the "backward cross type" in other mammals is thought to be worthy of notice.2. Movements of four limbs in walking were expressed as the combination of reciprocal movements of right and left fore limbs and that of right and left hind limbs, as shown in Fig. 11-Fig. 12 or Fig. 13-Fig. 15. (cf. Fig. 7, 8, 9). The body support fashion by the limbs while walking with either of the two types was illustrated in Fig. 16 and Fig. 17, 18 (cf. Fig. 10), and the stability of animal body was discussed. In these figures it is obvious that "forward cross type" is rather unstable compared with "backward cross type ". Monkeys may compen-sate the instability in walking with highly developed postural regulation mechanism.3. In walk, ipsilateral fore limb and the contralateral hind limb have the tend-ency of moving together ; and when these two limbs are in retraction phase, either of the protracting two limbs (other fore limb and the contralateral hind limb) must be placed on the ground earlier not to lose the equilibrium of the body if the center of gravity is situated before or behind the line connected between two supporting feet of the limbs. If the center of gravity is before the line, the protracted fore limb must be placed on the ground first ; thereafter "backward cross type" begins. If the center of gravity is behind that line, the protracted hind limb must be placed on the ground first not to tilt the body backwards, then thereafter "forward cross type" occurs.In many non-primate mammals, the body weight falls more heavily on the fore limbs than on the hind limbs (cf. Fig. 19, also IWAMOTO & TOMITA 1966), but in monkeys the body weight falls more heavily on the hind limbs than on the fore limbs (cf. Fig. 20, also IWAMOTO & TOMITA 1966). The difference of the body weight distribution to fore and hind limbs between monkeys and other mammals may be related to the two walking types.4. The author also made dogs to walk with heavy load on the hip. In most cases the animal walked with "backward cross type ", but a few cases of "for-ward cross type" occurred. The author made some discussion on this result. An example of such "forward cross type" walk is shown in Fig. 22.