Movements at the carpometacarpal and metacarpophalangeal joints of the hand and their effect on the dimensions of the articular ends of the metacarpal bones.код для вставкиСкачать
THE ANATOMICAL RECORD 213:102-110 (1985) Movements at the Carpometacarpal and Metacarpophalangeal Joints of the Hand and Their Effect on the Dimensions of the Articular Ends of the Metacarpal Bones MOUNISSAMY BATMANABANE AND SRIVATSAN MALATHI Department of Anatomy, Medical School, University of Calabar, Calabar, Nigeria ABSTRACT A detailed study was undertaken to quantify the range of various movements at the carpometacarpal and metacarpophalangeal joints of the hand in cadavers and compare the values so obtained with those in the living, measured with the help of skiagrams. Longitudinal sections of hand were also prepared to bring out the nature of articulations at the carpometacarpal joints. Based on the data available, metacarpal mobility formulae of 1 > 5 > 4 > 2 > 3 for the carpometacarpal, and 5 > 4 > 3 > 2 > 1 and 5 > 2 > 4 > 3 > 1 for metacarpophalangeal joints are being proposed with the hope that these formulae will find their application in the clinical practice to assess the extent of functional damage t o these joints as well as to evaluate the rate of progress or deterioration, in course of time. As a n extension of our earlier study (Batmanabane, 1982),osteometric analysis of the metacarpus was also carried out and it is confirmed that it is the mobility which determines the osteometric features of the articular ends of these miniature long bones. One of the important evolutionary changes that the primates have undergone is the transformation of the hand from an organ of progression to one of prehension, perception, and expression. The metacarpals are designed chiefly to adapt the hands for prehension. The performance of the hand is dependent on the movements between the different components of the hand, taking place a t different joints. Hence these joints, especially the carpometacarpal and the movements occurring in them, have attracted the attention of many workers. Although the first carpometacarpal joint (CMJ) is the most analysed one, a few reports are available regarding the other joints as well. Some gliding movement is possible a t the carpometacarpal and intermetacarpal joints of the second to fifth fingers (Gardner et al., 1975). A small but useful range of movement a t the base of the fourth metacarpal (MC4) and a wider range of movement a t the base of the fifth (MC5) aid in the approximation of the two borders of the hand, thereby deepening the cup of the palm. Movements of the thumb have been studied by various authors (Backhouse, 1960; Bunnell, 1938; Haines, 1944; Napier, 1955) and the general observations on the functional aspect of the hand have been done (Landsmeer, 1962; McFarlane. 1962; Napier, 1956). Earlier reports (Batmanabane, 1981a,b)suggested that the movements rather than the length may be responsible for the various dimensions of the metacarpals a t their articular ends. Though the occurrence of movements at each of CMJs and metacarpophalangeal joints (MPJs) was known (Harris and Joseph, 1949), the exact range of movements available at each of these joints has @ 1985 ALAN R. LISS, INC. not been investigated thoroughly and the range of movements of the metacarpal bones, as measured in cadavers, has not been verified radiographically in the living. Hence, a detailed analysis of movements at CMJs and MPJs was considered meaningful, especially because these movements seem to influence the osteometric features of the metacarpus. Hence this study was designed to quantify the available movements a t CMJs and MPJs and find a correlation between these movements, the metacarpal lengths, and indices of various diameters of these bones. MATERIALS AND METHODS 1) Fresh specimens of ten normal adult hands from cadavers, aged between 26 and 42, were used for the measurement of movements a t each of the CMJs and MPJs. All hands were checked radiologically and found to have had no evidence of past injury or disease of the bones and joints. 2) For measuring the range of movements of the metacarpal in the living, radiographs of adult hands of individuals in the same age group, all manual laborers, irrespective of side and sex, were taken. 3) Specimens of intact hand, from both sides of six fresh cadavers, were sectioned to bring out the details of articulation a t CMJs. Received April 30, 1984; accepted April 5, 1985. 103 MOVEMENTS AND MORPHOLOGY OF METACARPUS 4) For anthropometric study, 50 adult samples from each of the metacarpus were selected. The fresh adult hand specimens were dissected free of all structures except the ligaments and capsules of the joints of the hand; the deep transverse metacarpal ligament was well preserved. For measuring the angular movements in cadavers, the following simple devices were made: to a n inflexible thick copper wire two sharp short pins were soldered a t right angles to the wire at convenient points, depending upon the bone for which this particular device is intended one set was made with the pins positioned in such a way that they could be driven into the head and the base of the metacarpals-one each for the long (second, third, and fourth) and short metacarpals (first and fifth). A second set was prepared to fit the length of the distal row of carpal bones and a third, the proximal phalanges. The metacarpal wire was fixed strongly along the length of MC1 and the carpal wire into the trapezium, both on the palmar aspect. The two pins were arranged in such a way that the wires were nearly at the same level but exactly parallel to each other, the joint being in the neutral position. The movement of maximum flexion was performed a t the CMJ and the angle between the wires was measured. This was followed by taking the measurement of the maximum extension movement at the same joint from the neutral position. MC1 was then fully adducted and the wires were adjusted. Bringing it to a fully abducted position, the angle between the wires was measured. This reading gave the full range of abduction (FRA; FRA is taken as the maximum amount of abduction that can be produced from the initial position of complete adduction). For measuring the rotation at the first CMJ, two wires were fixed vertically a t the same level and parallel to each otherone each on the dorsal aspect of MC1 and trapezium, the joint being in full extension. MC1 was then fully flexed and the angle measured. This gave the range of rotation. For measuring the range of movements at MPJ of MC1, one wire was fixed to the metacarpal and another to the corresponding proximal phalanx, both on the dorsal aspect. Observing the same precautions, the range of flexion, extension, and FRA were measured from the neutral position. Movements at other CMJs (FRF (vide infra) and FRA) and MPJs (flexion, extension and FRA) were also recorded in the same way as for the first, except that the wires were fixed on the dorsal aspect of the bones for all the measurements. Since the movements at CMJs of the medial four metacarpals are of limited range, it was decided to measure FRA and the full range of flexion (FRF), which is taken as the maximum amount of flexion that can be produced from the initial position of complete extension. The readings (a mean of three) were taken, avoiding errors of parallax (Tables 1, 2). A transparent plastic protractor was used for the purpose throughout the study. Skiagrams of the hand of 30 individuals in all were taken in the following positions: a) All fingers and the thumb in full adduction, b) the fingers in full abduction and the thumb partially extended at its CMJ, c) the thumb in neutral position, d) the thumb fully extended a t its CMJ and MPJ, and el MPJs of fingers and the thumb in the neutral, fully flexed, and extended positions. Since abduction at the pollicial MPJ is practically nil, no separate skiagram was taken. The following axes were drawn on the exposed x-ray plates: In “a” the long axes for the medial four metacarpals, their proximal phalanges, and for the hamate were drawn. The angles between i) the long axis of MC5 and hamate and ii) the long axis of the metacarpal and its corresponding proximal phalanx were measured (resting angles). A fixed point of 7 mm was taken from the distal end of the axis of each of the four medial metacarpals. The adjacent points were joined (Fig. 1). The distance between the adjacent points were also measured in mm. In “b”, the same procedure was followed as in “a” and the new sets of readings were taken (Fig. 2). Differences between corresponding readings as in “a” and “b” were taken as i) the amount of FRA occurring at the CMJ of the little finger and ii) MPJs of the medial four digits. Any increase in the intermetacarpal distance will offer a rough indication of the degree of movement of abduction a t other CMJs. For this purpose, during the exposures of “a” and “b”, a constant position of the middle finger (the axis for the movements of the hand) and the wrist was maintained. In “c” the long axes of MC1 and the trapezium were drawn and the angle between these was measured (resting angle) (Fig. 3). In “8’ the same procedure was followed as in “a” and a new set of readings was taken (Fig. 4). Difference between corresponding readings in “c” and “d” was calculated (angle of extension). To measure the movements at MPJs, the long axes of the metacarpal and its phalanx in the neutral, flexed, extended, and abducted positions were drawn and the angles were recorded. The procedure for the anthropometric study was the same as described elsewhere (Batmanabane, 1982). The axial ratios were determined and the data statistically analysed. RESULTS Movements at CMJs-As Measured in Cadavers The mean values of the degree of mobility of the metacarpal bones at their respective CMJs are shown in Tables 1 and 2. There is a comparatively greater amount of extension at the CMJ of the thumb than flexion and the amount of rotation exceeds that of flexion and extension taken individually. Among the medial four metacarpals, MC5 displayed a maximum amount of FRF and FRA followed by MC4, MC2, and MC3, in that order. Movements at MPJs-As Measured in Cadavers The mean values of movements occurring a t these joints are summarized in Table 3. Concerning flexion and extension, the order of mobility gave the picture of MC5 being the most mobile followed by MC4, MC3, MC2, and MC1. However, regarding FRA, the order was slightly different, with MC5 leading followed successively by MC2, MC4, MC3, and MC1. M. BATMANABANE AND S. MALATHI 104 Fig. 1. Skiagram of the right hand showing the long axes of MC2, MC:l, MC4, and MC5 and the hamate, the CMJs in full adduction. Note the axis of MC5 intersecting that of hamate. Fig. 2. Skiagram of the right hand, showing the same axes as in Figure 1 but the CMJs in full abduction. Note the axis of MC5 lying medial to that of hamate. Movements at CMJs-As Measured From Skiagrams partly mobile factor, the capitate as a factor of stability, and the hamate as a gliding base for the fourth and especially the fifth metacarpal. The articulation between the trapezium and MC1 is built like a saddle joint, concave in anteroposterior plane and convex in the lateral plane a t the base of MC1 and vice versa a t the contiguous surface of trapezium, which permits the various available movements (Fig. 5). The first CMJ is closely packed in full adduction or abduction and freest movements can occur when it is in the neutral position. Although the movements of the thumb involve flexion more often than extension, it was interesting to find that the amount of the latter movement at the first CMJ exceeded that of the former. Even though the available movements in the medial four CMJs are said to be pure translations and in reality accessory movements of the first type, these are often considered to be the only motion permitted. However, even here, examination of cineradiographs reveals a considerable degree of rotation and angular change in the relative positions of the small bones during most movements of the carpus (Williams and Warwick, 1980). MC3, the middle member of the metacarpal series, which maintains the central axis of the pentadactyle hand, is particularly immobile and there is every reason to expect that its immediate neighbours, MC2 and MC4 (Figs. 6, 7), will primitively display a n equally lessened degree of mobility (Jones, 1949). But the simplest test will convince us that the mobility of MC2 is far less than The values for extension at the first and abduction a t the fifth CMJs are summarized in Table 4. Since facilities for taking tomograms were not available further analysis of movements could not be carried out. Movements at MPJs-As Measured From Skigrams These values are shown in Table 5. The graded range of movements a t these joints, in the living, correlated well with those values obtained in cadavers. Statistical Analysis In line with earlier findings, the side-to-side diameter of the heads of MC2, MC3, MC4, and MC5 were greater than the dorsopalmar diameter and the significance of this finding has been discussed elsewhere (Batmanabane, 1982). Table 6 summarises the mean 1 S.E.M. values of the different parameters. Highly significant values were obtained for all the metacarpal bones when the data were submitted to a “t” test, while the values of the coefficient of correlation were all insignificant. DISCUSSION If the carpal bones are taken as the foundation upon which the hand is built, the trapezium becomes significant as a base for the mobile thumb, the trapezoid as a 105 MOVEMENTS AND MORPHOLOGY OF METACARPUS Fig. 3. Skiagram of the right hand showing the long axes of MC1 and the trapezium, t h e first CMJ in the neutral position. Fig. 4. Skiagram of the same right hand showing the same axes a s i n Figure 3, t h e first CMJ i n full extension. TABLE 1. Mean f S.E.M. values of movements of MCI at its CMJ, as measured in cadavers' Metacarpal MC1 Flexion ~ Extension L R 22.2 k 0.904 R 17.7 & 1.033 L 28.7 26.9 k 0.843 k 1.464 Abduction (FRA) R L 37.5 34.7 0.931 k 1.335 Rotation R L 30.9 0.9 29.2 0.663 'Abduction and rotation movements were measured from initial positions of complete adduction and extension, respectively. Mean values a r e in degrees. TABLE 2. Mean f S.E.M. values of movements at the medial four CMJs, as measured in cadavers' Metacarpals MC2 MC3 MC4 MC5 Flexion (FRF) Abduction (FRA) R L R L 12.1 L- 0.9 5.8 0.359 16.9 & 0.731 26 t 1.366 11.6 k 0.718 5.1 k 0.26 14.6 & 1.316 23.7 k 1.256 2.3 & 0.213 2.1 f 0.314 + N.D.~ 5 & 0.258 13.6 5 0.286 N.D. 4 k 0.258 13.3 f 0.26 'Flexion and abduction movements were measured from initial positions of complete extension (FRF) and adduction (FRA), respectively. Mean values a r e i n degrees. 'N.D., not done. that which can be evoked in MC4. This is a specialisa- to a fair degree and MC2 practically not at all, but our tion of the index for a n unusual degree of stability. This observation shows that MC2 can indeed be moved so is explained by the nature of its situation where it is dorsally, though to a very limited extent, in the living. sandwiched between the trapezium and the capitate, This is reflected in our findings in cadavers, where FRF resting on the trapezoid. Gardner et al. (1975) remarked averaged 12.1" on the right and 11.6" on the left. Althat MC5 can be passively moved forward and backward though MC3 is the most fixed, even a t its CMJ a mini- 106 M. BATMANABANE AND S.MALATHI TABLE 3. Mean Metacarpals S.E.M. values of movements of the metacarpal bones at their respective MPJs, as measured in cadavers' Flexion Extension L R MC1 MC2 MC3 MC4 MC5 47.2 f 0.611 70.1 f 1.089 79.9 k 1.089 96.6 f 1.726 102.3 f 1.366 44.1 63.3 74.1 92.9 96.4 f 0.721 f 1.164 f 2.153 f 1.662 k 1.249 FRA R L R L 16.2 f 0.997 45.5 f 1.368 55.1 f 1.32 64.3 k 1.591 69.2 f 1.356 14.8 f 0.975 41 1.316 51.8 f 1.051 60.8 f 1.576 65.5 f 1.522 2.7 k 0.226 35.8 f 0.872 7.7 f 0.336 18.3 f 0.541 38.1 f 0.921 1.8 f 0.199 31.9 i 0.743 5.6 f 0.237 14.1 f 0.499 35.9 f 0.881 'Mean values a r e in degrees. TABLE 4. Mean 1 S.E.M. values of movements of extension of MC1 and abduction of MC5 at their respective CMJs, as measured from skiagrdms' Metacarpals Extension MC1 MC5 Abduction (FRA) R L R L 19.3 0.238 N.D.~ 18.8 k 0.133 N.D. N.D. 12.9 0.752 N.D. 10.1 k 0.314 'Extension was measured from t h e neutral position and abduction from a n initial position of complete adduction. Mean values a r e in degrees. 'N.D., not done. TABLE 5. Mean f S.E.M. values of movements of the metaca al bones at their respective MPJs, as measured from skiagrams T Metacarpals MC1 MC2 MC3 MC4 MC5 Flexion R 43.8 66.2 70.7 87.3 94.4 f 0.813 i 1.093 +_ 0.7 k 1.075 f 0.845 L 40.9 i 0.766 60.5 i 1.035 64.1 i 1.0203 81.4 i 1.045 90.1 f 1.157 Extension R L 14.4 i 0.6 11.5 f 0.6006 39.6 f 1.359 36.6 L- 1.447 47 i 0.9306 43.2 i 0.696 58.1 f 0.438 53.9 i 0.448 62.3 i 1.087 60.1 f 1.069 FRA R L - - 31.4 f 0.721 5.2 f 0.198 15.7 f 0.501 33.6 f 0.799 28.1 f 0.596 3.8 k 0.122 13.5 f 0.489 29.7 0.611 'Mean values are in degrees. TABLE 6. Mean f S.E.M. values of length and axial ratios of the metacarpals' Metacarpals Length MC 1 MC2 MC3 MC4 MC5 4.4 6.61 6.24 5.57 5.1 f 0.026 f 0.079 f 0.073 i 0.073 f 0.053 Head Axial ratios Mid-shaft Base 1.9 k 0.01 0.992 f 0.011 1.06 f 0.009 0.986 f 0.014 0.99 k 0.007 1.33 i 0.016 1.076 k 0.022 1.12 0.012 1.119 f 0.024 0.89 f 0.005 1.01 f 0.007 1.063 f 0.014 1.3 f 0.013 1.072 i 0.018 0.9 f 0.007 * 'The length values a r e in cm. ma1 degree of flexion was found to be available (Table 2) in the cadavers. This is easily interpretable in the light of the postmortem changes in the ligaments of the joints and other factors (vide infra). Certainly MC4 presented a fair amount of movement, but compared only to MC5 which displayed the widest range of movements among the medial four metacarpals, probably because of its condylar type of articulations with the hamate (Fig. 8). MC5 rotates about MC4 because of its articulation with the latter and the saddle type of joint with the hamate, permitting such a rotation to occur (Fig. 9). Thus, fourth and fifth CMJs are indeed biaxial joints rather than mere plane joints, as observed from the available movements and the sections of hand speci- mens. Among the movements a t CMJs, only extension of MC1 and abduction of MCS could be verified radiologically in the living. These values were found to more or less correspond to those obtained in cadavers, the values in the living being slightly less, (compare Tables 1 and 2 with 4).This may be due to various factors causing limitation of movements in the living, such as the tension of ligaments-an integral factor in producing the close-packed position of a joint, the tension of the antagonistic muscles, and the soft tissue opposition during the performance of these movements. The fact that there is an increase in the intermetacarpal distance gives a rough and yet a positive evidence of the availability of abduction at the second and the fourth CMJs. Based on MOVEMENTS AND MORPHOLOGY OF METACARPUS Fig. 5. Photograph of the longitudinal section of the hand passing through MC1 and the corresponding carpal bones. Note the articulations between MC,, the trapezium, and the scaphoid. Fig. 6. Photograph of the longitudinal section of the hand passing through MC2 and the corresponding carpal bones. Note the articulations between MC2, the scaphoid, the trapezium, and the trapezoid. 107 108 M. BATMANABANE AND S. MALATHI Fig. 7. Photograph of the longitudinal section of the hand passing through MC3 and the corresponding carpal bones. Note the articulations between MC,, the capitate, and the lunate. Fig. 8. Photograph of the longitudinal section of the hand passing through MC, and the corresponding carpal bones. Note the condylar type of articulation between MC, and the hamate. MOVEMENTS AND MORPHOLOGY OF METACARPUS 109 Fig. 9. Photograph of the longitudinal section of the hand passing through MC5 and the corresponding carpal bones. Note the saddle type of articulation between MC5 and the hamate. these findings and in line with the logic of the metacar- and MC1 the least, leading to a metacarpal mobility pal formula, we propose a metacarpal mobility formula f o r m u h of 5 > 4 > 3 > 2 > 1as far as flexionlextension of 1 > 5 > 4 > 2 > 3 for CMJs. is concerned and 5 > 2 > 4 > 3 > 1 with respect to At MPJs, as far as FRA is concerned, MC5 emerges to abductionladduction a t MPJs. Radiological analysis of be certainly the most mobile, and not MC2 as mentioned these movements, in the living, conformed to this by Williams and Warwick (1980). Indeed, MC5, forming gradation. the medial boundary of the bony framework of the penWe are of the opinion that the acceptance of these tadactyle hand, should be expected to enjoy the highest formulae will be very useful clinically for immediate degree of mobility in order to adapt itself to various qualitative assessment of a) the extent of damage to any objects grasped to offer the best grip possible to the of these joints under various pathological conditions and prehensile hand, just like its counterpart, MC1. The only b) their subsequent functional recovery or further loss difference is MC1 is most mobile a its CMJ and MC5 a t after treatment. Thus, these observations, condensed in its MPJ (vide infra). We consider t ‘s a very vital ar- the form of metacarpal mobility formulae, would be very rangement which will provide a n element of stability handy in the evaluation of hand function. without prejudice to the mobility of these joints in this From the statistical analysis of the data obtained from functionally specialised organ. the measurements of the metacarpal bones, it was eviMC5 is followed by MC2, MC4, and MC3, in that order, dent that these miniature long bones are distinctively with MC1 displaying a very negligible range. different from each other in all parameters with the Y’ Other minor movements, consisting of rotation, dis- values found to be much higher than the tabulated valtraction, and gliding, have been omitted since these are ues a t 0.1% level of significance. Reviewing the values really accessory movements and their values, if mea- of the coefficient of correlation, it was found that the ‘Y’ sured, may not truly reflect their exact range since these values were insignificant in all cases, confirming the are negligible. view (Batmanabane, 1982) that the length of the metaAlthough the extent of flexion at all MPJs is always carpal does not influence the various diameters of the more than that of extension, in both cadavers and the articular ends of these bones. living, it is to be remembered that a little more of extenThe metacarpal bones generally display a similar sion can still be produced passively in the living even shape despite a glaring difference in length. The existhough this will not make the totally available range of tence of a graded range of movements in them could be extension exceed that of flexion, as evidenced by the a factor effecting the osteometric features at their artifindings in the cadavers, where the movements were cular ends, especially in the absence of any possible role produced passively and yet the values of extension were of the length. If mobility should influence the morpholless than those of flexion in the living. From the obser- ogy of the metacarpus the effects will be seen mainly at vations of the available movements at MPJs, it is inter- the articular ends. The extent of the influence will deesting to note that MC5 emerges to be the most mobile pend upon the degree of mobility of the surfaces. Since a 110 M. BATMANABANE AND S. MALATHI movements occur in these joints along two axes, both dorsopalmar and side-to-side diameters of the ends will be involved while mobility is shaping the articular terminals of these bones.’ This means, where the movements in both planes are closer to each other in their extent, the dimensions should be affected so uniformly and almost equally that the axial ratio of that particular end should be nearer to one. If the ranges of movements are wider apart, the dimensions are going to be influenced differentially and the values of the axial ratios are going to be farther from one. This is clearly reflected in all the metacarpals, as observed in this study, where the mean axial ratios of the head are the ones closest to one and those of the base farthest in all but MC1, where the trend is reversed due to the fact that the base of MC1 is more mobile than its head. There is thus a close correlation between the diameters of the articular ends of the metacarpus and their relative mobility, which therefore appears to be a determining factor for the distinctive osteometric characteristics of these bones. However, it may sound very strange, a t the outset, to state that it is movements which determine the shape of the articular terminals of these bones. We may be tempted to favour the common view that only shapes dictate the type of movements that should occur in a joint and not vice versa. In order to arrive at a conclusion to the question “Movement first or shape first?” we should take into serious consideration the fact that, in the course of a long, arduous process of evolution, attempts of living organisms to adapt to a different habitat, from aquatic to terrestrial, to cite a n example, would put a lot of stress and strain on the joints during movements, and such initially difficult-to-perform movements will mould the joint surfaces in the course of time to make it easy for the animals to make a successful adaptation. Thus, only movement is the factor which appears to have a direct access or influence over the joint surfaces and hence will shape them over the long years (of evolution) depending on the need of the animals concerned. Is it not true that, in the case of the bones of the skull, where movement is not necessary or even desired, bones which come together are firmly connected with one another to form sutures? Are not “squatting facets” examples of structural modifications consequent to the peculiar posture of a particular type of DoDulation? In the words of Walter and Savles (1959). “Climbing, digging, flying, striking, standing, running: gasping and lifting are Only a few Of the many that make necessary structural adaptations.” Hence it is logical to believe that only movements dictated the design of the shapes of the articular ends of the bones, especially in the hand, which has evolved from having been a n organ of progression to one of prehension, perception, and expression. ACKNOWLEDGMENTS The author wishes to thank the head of the Department of Anatomy for making the facilities available for this study and the Committee of Deans, University of Calabar, for providing funds to attend the Winter Meeting of the Anatomical Society of Great Britain & Ireland, December, 1980, where a part of this work was presented. LITERATURE CITED Batmanahane, M. (1981a) Mobility-a major factor in the determination of the morphology of the human metacarpal hones. J.Anat., 132(3):458(Ahstract). Batmanahane, M. (1981h) A further study on the role of mobility as the determining factor for the morphology of metacarpal bones. J.Anat., 132(3):458(Abstract). Batmanahane, M. (1982) Whether mobility influences the osteometric features at the articular ends of the metacarpal bones. Acta Morphol. NeerlScand., 20(2):111-115. Backhouse, K.M. (1960)Digital rotation. J.Anat., 94.453. Bunnell, S.E. (1938) Opposition of the thumb. J. Bone Jt. Surg., 20(2):269-284. Gardner, E., D.J. Gray, and R. O’Rahilly (1975) The hand. In: Anatomy-A Regional Study of Human Structure. Saunders, Philadelphia, pp. 152-156. Haines, R.W. (1944)The mechanism of rotation at the first carpometacarpal joint. J.Anat., 78.44-46. Harris, H., and J. Joseph (1949) Variation in extension of metacarpophalangeal and interphalangeal joints of the thumb. J.Bone Jt. Surg. 31B547-559. Jones, F.W. (1949)The metacarpal formula. In: The Principles of Anatomy as Seen in the Hand. Bailliers, Tindall and Cox, London, pp. 53-59. Landsmeer, J.M.F. (1962) Power grip and precision handling. Ann. Rheum.Dis., 21:164-170. McFarlane, J.M. (1962) Observations on the functional anatomy of the intrinsic muscles of the thumb. J.Bone Jt. Surg., 444:1073-1088. Napier, J.R. (1955)The form and function of the carpometacarpal joint of the thumb. J.Anat., 89:362-369. Napier, J.R. (1956)The prehensile movements of human hand. J.Bone Jt. Surg., 38B:902-913. Walter, H.E., and L.P. Sayles (1959) The skeleton. In: Biology of the Vertebrates. The Macmillan Company, New York, pp, 606-607, 626-633. Williams, L.P. and R. Warwick (1980) Kinesiology: Arthrology. In: Gray’s Anatomy. Churchill Livingstone, Edinburgh, pp. 431-438, 470-472. ‘A study to map out and analyse the configurations of these joints is currently in progress.