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111 2 K.J. van Zwieten , P.L. Lippens , K.P. Schmidt , W. Duyvendak ,
K.S. La mur3, F.H.M. Narain 3,1.A. Zubova4, S.A. Varzin 4,
O.E. Piskun 4 and A.V. Zinkovsky 4
PRONATOR TERES MUSCLE AND REPETITIVE STRAIN INJURIES
department of Anatomy, BioMed, Universiteit Hasselt, Diepenbeek, Belgium, Department of Neurosurgery, Virga Jesse Hospital, Hasselt, Belgium, Department of Anatomy, University of Suriname, Paramaribo, Suriname,
4Department of Biomechanics, Saint-Petersburg State Polytechnic University,
Saint-Petersburg, Russia
Peripheral nerve entrapment neuropathies currently occur as 'tunnel syndromes' (cf carpal tunnel syndrome). The present study focuses on the anatomical features of the pronator teres muscle and the median nerve (innervating forearm flexors), investigated in normal human anatomical specimens by means of dissection, morphometry and roentgenphotogrammetry.
In planar movement of the human hand, e.g. a horizontal shift over a flat surface, rotation of the humerus is involved. Forward movement implies an internal rotation, backward movement an external rotation. This external rotation imposes some degree of pronation on the forearm. As a consequence, excessive repetitive forward-backward shifting of the hand (palm downwards) may result in stressing the m. pronator teres, and may eventually lead to pathological conditions like repetitive strain injuries (RSI) as well as entrapment neuropathies.
Holding the hand with the palm down during prolonged time can induce muscle fatigue, as well as muscle tension, within the pronator teres muscle. Part of such tension can be explained on the basis of active muscle insufficiency (1). Application of vibrostimulation treatment over a period of weeks therefore, recently proved to be successful in a majority of RSI-patients (2).
Humeral (superficial) and ulnar (deep) heads of m. pronator teres fuse, their common tendon inserting on the tuberositas pronatoria of the radius. N. medianus pierces m. pronator teres, accompanied by several tissues. A deep tendinous arc lines the muscle heads, crossing over n. medianus as to prevent its entrapment within the muscle. Within the pronator teres muscle, the median nerve is travelling through a slit-like space, rather than through a 'pronator tunnel'.
Mathematical vector analysis of forces indicates that the effective contribution of m. pronator teres to pronation of the forearm may be considered as somewhat limited. M. pronator teres' vector of elbow flexion appears to be about 4 x its pronating vector. Strong pronation can be produced however by a deep muscle of the forearm, m. pronator quadratus (3).
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-
