Stains: hematoxylin eosin. Ca: joint cavity. Gross organization of hip musculature has been well described previously [ 5 , 11 , 27 , 29 ]. The gross descriptions of muscular anatomy offer little additional insight to previous descriptions, except for a possible accessory muscle. As the muscle lies on the extensor side of the hip joint, this might best be considered a deep head of the femorococcygeus.
The remainder of this discussion will be devoted to more novel results. Although joint morphology has been subject to great scrutiny by students of primate anatomy e. The relatively recent increase in availability of high-resolution, nondestructive methods, such a computed tomography, seems to make the topic of great potential interest.
The thickness of the subchondral plate in primates was studied using computed tomography by Dewire and Simkin [ 6 ]. These authors found little variation in the thickness of the subchondral plate in the femur but significant variation in subchondral plate thickness of the acetabulum increased thickness with increased body size among primates. An unknown in their study, unavailable using computed tomography, is the thickness of AC across primates.
Micro-MRI, currently of great promise for studying osteoarthritis [ 33 ], may provide a viable avenue for studying AC in cadaveric primates.
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The destructive methods used to study AC in this study are admittedly an undesirable means to produce large samples of nonhuman primates for quantitative analyses. As a result, our sample is too small for a quantitative analysis. At present, however, no other method allows the same resolution to describe AC in minute detail.
Thus our preliminary observations may provide insight for future studies. In two of the species C. This relationship was not apparent in M. A difference observed between cheirogaleids and G. Paraffin sectioning can produce distortions that might alter the apparent thickness of tissues. For example, slight deviations in cutting plane could hypothetically make AC appear thicker from surface to subchondral plate if sectioning is not at a right angle to the subchondral plate.
While consistent cutting planes can be hard to achieve with paraffin blocks, there is a strong basis for an assertion that the results reflect true species differences. First, the range of AC thickness of G. Thus, the greater thickness of the AC is proportional to the subchondral plate. Presumably, planar distortion would affect not just the AC, but the subchondral plate as well.
Variations in articular cartilage thickness have been related to body weight in humans, where it has been suggested larger individuals have thicker AC in lower limb joints [ 35 ], and some scaling of AC thickness to body mass could be inferred by comparing M. AC thickness has also been related to anisotropic properties of the tissue, based on its tendency to grow based on region-specific response to the magnitude of hydrostatic pressure due to compressive loading [ 31 ].
That species differences relate only to body size seems unlikely since G. Thus, species differences may also relate to the contrasting locomotory behavior of cheirogaleids compared to Galago. At the present time, a broad perspective on primate AC is lacking, due to the lack of similar studies. An analysis of a larger taxonomic sample of primates, optimally with nondestructive methods, is needed to establish diversity in joint microanatomy as well as functional correlates.
These findings also provide an update on results presented by Atzeva et al. That study focused on ontogenetic changes in limb muscle mass distribution in cheirogaleids and other primates, with a limited discussion of hip musculature, since it could not be reliably dissected in perinatal specimens.
By including the hip muscle mass in the present study, a clearer view of the entire limb muscle mass distribution is provided here. The results of the present study confirm certain previous findings on muscular specializations of prosimian primates, for example, the well-developed thigh muscle mass in adult lesser galagos. In this regard, our findings on G. There are subtle differences between the cheirogaleids; it is unclear if these are functionally significant.
However, it may be noteworthy that the species' locomotor behavior is not described identically. Infant primates are not immediately adept at locomotion, perhaps especially those with highly specialized modes [ 36 ].
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At least, some leaping specialists are known to undergo postnatal proportional changes in the limbs and trunk [ 37 ]. Thus maturation of the skeletal system among species is of interest. Watts [ 10 ] argued that ossification sequences in the limbs are similar in many hominoids, New World monkeys, and prosimians a term used here as a grade of primates. If true, the results on degree of ossification of the hip are unsurprising.
Despite the different locomotor tendencies between cheirogaleids and galagids, and some locomotor differences within these families [ 15 ], all perinatal specimens were similar in the extent of ossification at the hip. Further work seems important. Very few prosimians have been studied regarding early skeletal maturation. In addition, our focus on the hip leaves unknown whether more distal joints vary in extent of ossification.
Our sample provides more detailed information on ontogeny of hind limb muscle mass. Previously, Atzeva et al. The findings in this study support this observation.
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The ratio in infants could actually be inflated, since one of the G. If this represents a broad characteristic of primates, it suggests that one advantage for the relatively long dependency of infant primates [ 38 , 39 ] is for hind limb muscular gain.
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Our data on ontogenetic changes in relative muscle mass are based on a slightly larger sample than a previous report [ 1 ], allowing some additional interpretation. The increased sample of C. This indicates a greater postnatal muscle mass gain in C. This may be interpreted to indicate that a greater degree of altriciality is associated with relatively less muscle mass at birth. The relatively altricial Varecia variegata also had high ratios. Previously, musculoskeletal changes across age have been discussed in terms of how they relate to locomotor ontogeny [ 14 , 37 ] particularly and how does ontogeny of locomotor anatomy relate to the transition from an unspecialized strategy e.
Atzeva et al.
Within hind limb segments, muscular mass distribution reflects adult locomotor behaviors. For example, leaping specialists tend to have proportionally large knee extensors in the thigh and perhaps large leg plantarflexors. Muscular mass is not distributed similarly between limb segments across age, however.http://senrei-exorcism.com/images/kids/nokia-7-track.php
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Previous studies have noted a shift in limb muscle mass from distal to proximal segments [ 1 , 14 ]. In one sense, this mass shift appears to correspond to a transition from predominantly grasping limb activities to locomotor activities in the limbs see Raichlen, [ 14 ], for discussion. However, Atzeva et al. Thus, an additional factor may underlie this proximal mass gain.
The results of the present study may shed additional light on this issue, by showing a pronounced muscle mass shift to the thigh in a species that habitually uses leaping behaviors as adults. For G. An interesting question would be to determine if a species relying more extensively on the hip musculature for leaping e. Interestingly, the species with the least specialized here, meaning the most dedicatedly quadrupedal locomotion as adults, C. Thus, muscle mass gain to specific limb segments may be a critical milestone for primates with extremely specialized modes of locomotion.
The authors thank B. Demes for numerous helpful discussions and M. Hamrick for preparations of selected histological sections. Martin generously made available a primate cadaver. This study was completed, in part, with the help of funding from Slippery Rock University. This is Duke Lemur Center publication no. National Center for Biotechnology Information , U.
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