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In quadrupeds internal rotation of the humerus and subsequent supination are related to locomotion. Internal humeral rotation is correlated with backward movement of the limb during the stance phase. In the opossum (4), an early predecessor of primates including man, the internal humeral rotation imposes supination of the forearm during propulsion stroke.
References
1. Lambrichts D. Van Zwieten K.J. Lippens P.L. Schmidt K.P. and Hauglustaine S. (2005)
The role of the pronator teres muscle in the arm during the rowing movement, at the end of the stroke. Proceedings of the 2nd international congress on "Sport and Health", St. Petersburg, Russia, 21-23 April, 2005. Under the auspices of the Secretary General of the Council of Europe, Mr. Terry Davis, 358 - 359, ISBN 5-94966-012-9.
2. Nackaerts K. (2006) Whole body vibration as an adjuvant therapy for treating repetitive strain injury (RSI). MSc Thesis in Physical Therapy, Provinciale Hogeschool Limburg, Departement Gezondheidszorg, Opleiding Kinesitherapie. Hasselt.
3. Basmajian J.V. and De Luca C.J. (1985) Muscles alive: their functions revealed by electromyography. 5th Edition, Williams and Wilkins, Baltimore, 281-285.
4. Landsmeer J.M.F., Devid A. and Van Leeuwen C. (1985) Functional and comparative aspects of the forearm and wrist. Acta Morphol. Neerl.-Scand. 23, 65-66
K.J. van Zwieten1, A. Reyskens1, P.L. Lippens1, R.V. Mahabier2, K.S. Lamur2, K.P. Schmidt1 and I.A. Zubova3
INVERSION MOVEMENTS OF THE HUMAN FOOT IN POSITIONS PRIOR TO THE SWING PHASE OF THE STEPCYCLE: FUNCTIONAL
AND ANATOMICAL ANALYSIS
department Medische Basiswetenschappen, BioMed Institute, Universiteit Hasselt, Diepenbeek, Belgium; Department of Anatomy, University of Suriname, Paramaribo, Suriname; Department of Biomechanics, Saint-Petersburg State Polytechnic University, Saint-Petersburg, Russia
Introduction
In normal human gait, just prior to the swing phase of the step cycle, the foot shows a slight inversion movement at the end of the stance phase. In inver-
sion, the sole of the foot turns inward. During the swing phase this position of inversion is more or less maintained, until touchdown at the beginning of the next stance phase. If however a foot in inversion lands on its lateral side, a so-called inversion traumatism can occur, in activities of daily living, and even more frequently in various kinds of sports (Van Zwieten et al., 2007). Understanding and prevention of the pathology requires insight in the mechanism of movement. Therefore an anatomical and kinematical study was performed, on dissected specimens of lower leg and foot.
As most researchers focused on tarsal mechanics, we studied rotations of the first metatarsal bone around its longitudinal axis. These were calculated in the normal so-called push-off positions prior to swing. The rotations were related to normal stance as well as to extreme inversion during push-off. Moreover, these angles of rotation give information of the amount of inversion of the freely moving foot during the swing phase.
Background
In this anatomical study, the mobility of the foot with respect to its first ray was studied, especially during the inversion movement of the gait cycle (push-off phase). During walking, at the end of the stance phase, just before the foot looses contact with the substrate (swing phase), the foot is slightly inverted while the lower leg shows external rotation. This particular movement is related to several types of injuries. Based on the results of our in vitro measurements, it is concluded that more precise methods must be used in these types of investigation, e.g. in vivo observations.
Methods
X-ray pictures of ten anatomical specimens were studied. Metric parameters were measured from tracings of these pictures. The X-rays were taken with the lower legs in three positions: normal stance phase, push-off (inversion) and extreme inversion.
In each foot, reference marks (metal screws, 'intracortical pins') are inserted in the first metatarsal bone at standardized positions (Arndt et al., 2004). These screws are visible on the X-rays. Based on length changes of the projections of these screws in the X-rays, rotation angles of the first ray during push-off were calculated.
Results
It was expected that while the first metatarsal bone of the foot rotates around its longitudinal axis during inversion, the screws rotate away from the RX-film. Because of this, the projections of the screws on the RX-images would become shorter in push-off and in extreme inversion of the foot, in comparison with their projections in normal stance. Some of our results however are contrary to this expectation. These results can be explained on the basis of inaccuracies as a consequence of the X-ray procedure. The remaining measurements nevertheless show that in anatomical specimens at the position of push-off, the
average rotation of the first metatarsal around its longitudinal axis, measured distally, amounts 9°.
Conclusion
On the basis of the present investigation it can be concluded that the first ray of the foot, measured distally at the level of the first metatarsal bone in anatomical specimens, performs a small rotation movement around its longitudinal axis during the push-off phase of the gait cycle.
References
1. Van Zwieten K.J., Robeyns I., Vandersteen M., Lippens P.L., Mahabier R.V., Lamur K.S. (2007) Foot muscles preventing inversion traumatisms. Medicine and science in tennis 12, 2, 34-35.
2. Arndt A., Westblad P., Winson I., Hashimoto T., Lundberg A. (2004) Ankle and subtalar kinematics measured with intracortical pins during the stance phase of walking. Foot and ankle international 25, 5, 357-364.
K. J. van Zwieten1, I. Robeyns1, M. Vandersteen1, P. L. Lippens1, R. V. Mahabier2 and K. S. Lamur2
SOME FOOT MUSCLES PREVENTING INVERSION TRAUMATISMS
department of Anatomy, BioMed, Universiteit Hasselt, Diepenbeek, Belgium;
Department of Anatomy, University of Suriname, Paramaribo, Suriname
Abstract
Tennis players often perform landings on one foot in inverted position. In Sports Medicine therefore, ankle sprains after inversion traumatisms of the foot are the most common tennis injuries.
In this theoretical study, the role of some foot muscles in preventing inversion traumatisms was examined. During the swing phase of normal gait, some intrinsic foot muscles may be active in everting the foot prior to landing. Our kinematical approach consists of assessment of metric parameters measured in radiographs of lower legs and feet of anatomical specimens. The study confirms that m. peroneus longus is a strong evertor. The transverse head of m. adductor hallucis may evert the foot as well and prevent inversion traumatisms. Remarkably, this caput transversum of m. adductor hallucis was absent in 3 out of 10 anatomical specimens.
Introduction
The normal human stepcycle of each leg consists of a stance phase and a swing phase. The end of each stance phase is preceded by take-off of the heel, after which the medial side of the foot looses contact with the substratum. Initially, the lateral side of the foot stays in contact with the ground. Hereby the
