Muscle architecture of the upper limb in the orangutan

The maximum capability of a muscle can be estimated from simple measurements of muscle architecture such as muscle belly mass, fascicle length and physiological cross-sectional area. While the hindlimb anatomy of the non-human apes has been studied in some detail, a comparative study of the forelimb architecture across a number of species has never been undertaken. Here we present data from chimpanzees, bonobos, gorillas and an orangutan to ascertain if, and where, there are functional differences relating to their different locomotor repertoires and habitat usage. We employed a combination of analyses including allometric scaling and ANCOVAs to explore the data, as the sample size was relatively small and heterogeneous (specimens of different sizes, ages and sex). Overall, subject to possible unidentified, confounding factors such as age effects, it appears that the non-human great apes in this sample (the largest assembled to date) do not vary greatly across different muscle architecture parameters, even though they perform different locomotor behaviours at different frequencies. Therefore, it currently appears that the time spent performing a particular behaviour does not necessarily impose a dominating selective influence on the soft-tissue portion of the musculoskeletal system; rather, the overall consistency of muscle architectural properties both between and within the Asian and African apes strengthens the case for the hypothesis of a possible ancient shared evolutionary origin for orthogrady under compressive and ⁄ or suspensory loading in the great apes.

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“…2009) and data are available for a number of chimpanzees and orangutans (Thorpe et al. 1999; Carlson, 2006; Oishi et al. 2008, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…chimpanzee: Thorpe et al. 1999; Carlson, 2006; orangutan and chimpanzee: Oishi et al. 2008, 2009; gibbon: Michilsens et al.…”

Section: Introductionmentioning

confidence: 99%

Functional adaptations in the forelimb muscles of non‐human great apes

et al. 2011

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“…The mass, PCSA, and fascicle length of the thigh muscles from the same specimen are also presented in the Appendix. Such complete data of the muscle dimensions are essential for understanding the form-function relationship of musculature in hominoids [e.g., 6,7]. We hope to have more opportunities to dissect the feet of both lowland and mountain gorillas for comparative analysis of the intra-and inter-subspecies variations in muscle architecture in gorillas, which might reflect differences in their habitats and locomotor behaviors.…”

Section: )mentioning

confidence: 99%

Dimensions of the Foot Muscles in the Lowland Gorilla

Oishi

Ogihara

Endo

et al. 2009

The Journal of Veterinary Medical Science

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ABSTRACT. We dissected the hindlimb of a female western lowland gorilla and determined the muscle dimensions (mass, fascicle length, and physiological cross-sectional area: PCSA). Comparisons of the muscle parameters of the measured gorilla with corresponding reported human data demonstrated that the triceps surae muscles were larger and had more capacity to generate force than the other muscle groups in both species, but this tendency was more prominent in the human, probably as an adaptation to strong toe-off during bipedal walking. On the other hand, PCSAs of the extrinsic pedal digital flexors and digiti minimi muscles were larger in the western lowland gorilla, suggesting that the foot, particularly the fifth toe, has a relatively high grasping capability in the lowland gorilla.KEY WORDS: foot, gorilla, muscle architecture.J. Vet. Med. Sci. 71(6): 821-824, 2009 Gorillas are generally regarded as the most terrestrial of the extant hominoids. However, the degree of arboreality is known to vary among subspecies. Mountain gorillas (G. gorilla beringei) living in eastern central Africa seem to be the least arboreal, and the amount of time they spend above ground is only 7% in females and 2% in males [1]. On the other hand, western lowland gorillas (G. g. gorilla) in western central Africa are observed to be more arboreal and are frequently found in trees higher than 20 m [1,9]. Such differences in the degree of arboreality among the subspecies are correlated with foot anatomy. The foot of the western lowland gorilla has a relatively longer free portion of the first toe capable of opposing to the other four toes for grasping, whereas that of the mountain gorilla is relatively more humanlike and adapted for terrestrial locomotion [10,11].Therefore, understanding subspecies variations in the muscular characteristics of the gorilla foot is important for interpreting functional adaptations of the foot in hominoids. However, although Payne et al. [8] have reported the muscle architecture of the gorilla's hindlimb, no studies so far have provided complete quantitative data on all of the foot muscles, including the intrinsic muscles.In this study, we dissected the left hindlimb of a female western lowland gorilla to provide complete quantitative * CORRESPONDENCE TO: OISHI, M., First Department of Anatomy, School of Veterinary Medicine, Azabu University, 1-17-71, Fuchinobe, Sagamihara, Kanagawa 229-8501, Japan. e-mail: dv0502@azabu-u.ac.jp Tables 1 and 2.

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“…Other approaches to gorilla and orangutan anatomy have addressed function with quantitative information by focusing on one component, for example skeletal proportions (e.g., Schultz, 1930Schultz, , 1937Schultz, , 1956); biomechanics of scapula or limbs (e.g., Miller, 1932;Oxnard, 1967;Roberts, 1974;Taylor, 1997), regional muscle and limb weights and inertial properties (e.g., Preuschoft, 1961Preuschoft, , 1963Payne et al, 2006a, b;Isler et al, 2006;Oishi et al, 2008Oishi et al, , 2009). On live captive gorillas and orangutans, direct measures of muscle function or joint motion derive from electromyography during specific limb movements (e.g., Basmajian, 1974a, b, 1978;Tuttle et al, 1975;Stern and Susman, 1981;Tuttle et al, 1983) and from cinematography of climbing modes (e.g., Isler and Thorpe, 2003;Isler, 2005).…”

Section: Introductionmentioning

confidence: 99%

Functional Anatomy and Adaptation of Male Gorillas (Gorilla gorilla gorilla) With Comparison to Male Orangutans (Pongo pygmaeus)

Zihlman

McFarland

Underwood

2011

The Anatomical Record

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Great apes diversified during the Miocene in Old World forests. Two lineages, gorillas in Africa and orangutans in Asia, have sexual dimorphisms of super-sized males, though they presumably diverged from a smaller common ancestor. We test the hypothesis that they increased in body mass independently and convergently, and that their many postcranial differences reflect locomotor differences. Whole body dissections of five adult male gorillas and four adult male orangutans allowed quantification of body mass distribution to limb segments, of body composition (muscle, bone, skin, and fat relative to total body mass), and of muscle distribution and proportions. Results demonstrate that gorilla forelimb anatomy accommodates shoulder joint mobility for vertical climbing and reaching while maintaining joint stability during quadrupedal locomotion. The heavily muscled hind limbs are equipped for propulsion and weight-bearing over relatively stable substrates on the forest floor. In contrast, orangutan forelimb length, muscle mass, and joint construction are modified for strength and mobility in climbing, bridging, and traveling over flexible supports through the forest canopy. Muscles of hip, knee, and ankle joints provide rotational and prehensile strength essential for moving on unstable and discontinuous branches. We conclude that anatomical similarities are due to common ancestry and that differences in postcranial anatomy reflect powerful selection for divergent locomotor adaptations. These data further support the evolutionary conclusion that gorillas fall with chimpanzees and humans as part of the African hominoid radiation; orangutans are a specialized outlier. Anat Rec, 294:1842Rec, 294: -1855Rec, 294: , 2011. V V C 2011 Wiley-Liss, Inc.

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Muscle architecture of the upper limb in the orangutan

Abstract: In the ''Methods'' section, the first sentence of the first paragraph should read: A left upper limb of a female Sumatran orangutan (Pongo abelii) was obtained for dissection from Higashiyama Zoo and Botanical Gardens, Aichi, Japan, through the Great Ape Information Network (GAIN).

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Functional adaptations in the forelimb muscles of non‐human great apes

Functional adaptations in the forelimb muscles of non‐human great apes

Dimensions of the Foot Muscles in the Lowland Gorilla

Functional Anatomy and Adaptation of Male Gorillas (Gorilla gorilla gorilla) With Comparison to Male Orangutans (Pongo pygmaeus)

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