Biomechanics of mammalian terrestrial locomotion

Mammalian skeletons experience peak locomotor stresses (force per area) that are 25 to 50% of their failure strength, indicating a safety factor of between two and four. The mechanism by which animals achieve a constant safety factor varies depending on the size of the animal. Over much of their size (0.1 to 300 kilograms), larger mammals maintain uniform skeletal stress primarily by having a more upright posture, which decreases mass-specific muscle force by increasing muscle mechanical advantage. At greater sizes, increased skeletal allometry and decreased locomotor performance likely maintain stresses constant. At smaller sizes, skeletal stiffness may be more critical than strength. The decrease in mass-specific muscle force in mammals weighing 0.1 to 300 kilogram indicates that peak muscle stresses are also constant and correlates with a decrease in mass-specific energy cost of locomotion. The consistent pattern of locomotor stresses developed in long bones at different speeds and gaits within a species may have important implications for how bones adaptively remodel to changes in stress.     

Symmetry in running

Symmetry plays a key role in simplifying the control of legged robots and in giving them the ability to run and balance. The symmetries studied describe motion of the body and legs in terms of even and odd functions of time. A legged system running with these symmetries travels with a fixed forward speed and a stable upright posture. The symmetries used for controlling legged robots may help in elucidating the legged behavior of animals. Measurements of running in the cat and human show that the feet and body sometimes move as predicted by the even and odd symmetry functions.     

床垫支撑力对侧卧姿势下肩关节生物力学的影响

对人体侧卧姿势下肩关节进行生物力学分析,建立了肩关节中盂肱关节、三角肌和冈上肌肌力的计算公式,探究了床垫支撑作用力对肩关节中盂肱关节力、三角肌和冈上肌肌力的影响。结果发现,随着床垫对肩部支撑力的增大至120 N时,盂肱关节力和三角肌肌力逐渐增大;当床垫对肩部支撑力大于120 N时,盂肱关节力和三角肌肌力逐渐减小。冈上肌肌力则随着床垫对肩部支撑力增大,呈现先减小后增大的趋势,在床垫支撑力在85 N左右时为该趋势的转折点。随着床垫对上肢支撑力的增大,盂肱关节力和三角肌肌力逐渐增大;冈上肌肌力则呈现先减小,后增大再减小的趋势,从生物力学角度阐明了人体在睡眠过程中需要进行睡姿调整的内在原因。     

Cumulative sperm whale bone damage and the bends

Diving mosasaurs, plesiosaurs, and humans develop dysbaric osteonecrosis from end-artery nitrogen embolism ("the bends") in certain bones. Sixteen sperm whales from calves to large adults showed a size-related development of osteonecrosis in chevron and rib bone articulations, deltoid crests, and nasal bones. Occurrence in animals from the Pacific and Atlantic oceans over 111 years made a pathophysiological diagnosis of dysbarism most likely. Decompression avoidance therefore may constrain diving behavior. This suggests why some deep-diving mammals show periodic shallow-depth activity and why gas emboli are found in animals driven to surface precipitously by acoustic stressors such as mid-frequency sonar systems.     

A mechanical trigger for the trot-gallop transition in horses.

It is widely thought that animals switch gaits at speeds that minimize energetic cost. Horses naturally switched from a trot to a gallop at a speed where galloping required more energy than trotting, and thus, the gait transition actually increased the energetic cost of running. However, by galloping at this speed, the peak forces on the muscles, tendons, and bones, and presumably the chance of injury, are reduced. When the horses carried weights, they switched from a trot to a gallop at a lower speed but at the same critical level of force. These findings suggest that the trot-gallop transition is triggered when musculoskeletal forces reach a critical level.     

野猪与长白猪骨骼的比较研究

[目的]揭示家猪和野猪骨骼的发育规律,探讨家猪与野猪的亲缘关系。[方法]对野猪和长白猪头骨、躯干骨和四肢骨的数量、长度、重量等解剖学特征进行比较。[结果]野猪全身骨骼总数246块,躯干骨骼80块,四肢骨骼数134块,比长白猪少,但野猪的头骨总数比长白猪多,为38块,野猪比长白猪多1块吻骨;野猪四肢骨的长度和数量均低于长白猪,但其重量与长白猪的差异不大;野猪胸廓的横径与纵径大于长白猪,表明野猪的血液循环系统和呼吸系统均强于长白猪。长白猪头小体长,腿臀部较发达,表明其在多年的选育和人为环境中已逐渐向肉用性能方面发展。[结论]该研究可为更好地利用野猪资源提供理论依据。     

平乐正骨“以筋为先,以衡为用”理念在退行性腰椎病中的应用分析

退行性腰椎病变主要是由于长期慢性劳损、不良姿势、退变致腰部筋伤,进一步发展累及于骨,导致腰椎失衡。"以筋为先,以衡为用"是平乐正骨"筋滞骨错"理论下筋骨病的治疗原则,旨在通过手法松筋、正骨、功能锻炼颐养筋骨等重建脊柱平衡,达到防治退行性腰椎病变的目的。     

不同营养水平对民猪和哈白猪影响的研究 Ⅱ.肌肉和骨骼生长发育规律

一、品种间差异 (一)正常饲养组在正常饲养情况下,哈白猪于50公斤体重以后,产肉量占绝对优势,而民猪在四肢骨长度上占优势,其中后肢骨表现最突出.在骨骼重量上两品种间无显著差异. (二)限制饲养组在维持和低维持饲养情况下,民猪不论在肌肉重量上,还是在骨骼重量和长度上都占优势,而且,随营养水平的降低优势程度越明显.由此充分说明,在营养缺乏的情况下,民猪在肌肉重量和骨骼重量与长度方面的抗逆性强于哈白猪. (三)限制饲养组恢复正常饲养总的结果表明:哈白猪和民猪尽管前期遇到营养严重缺乏(维持营养以下),如后期给予正常饲养补偿,两品种的产肉量基本相同,无显著差异,即缩小了两品种生产瘦肉能力的差异;但同时加大了骨骼长度的品种间差异;对骨骼重量的品种间差异无显著影响. 二、营养水平间的差异在70公斤体重阶段,哈白猪和民猪原限制饲养组的肌肉重量、骨骼重量和长度均与其正常饲养组拉平,即两品种限制饲养组都得到补偿.但很难下结论哪个品种的补偿力强. 三、肌肉和骨骼关系民猪股坐夹角比哈白猪小,而坐骨和股骨又比哈白猪长.因此,延长了股后肌群相对髋关节的力臂,相应增大力矩,提高肌肉功率,结果减少了股后肌群的重量.民猪这种肌肉骨骼结构特点有利于生存而不利于肌肉发育.     

Adaptations for climbing in north american multituberculates (mammalia)

A recently discovered skeleton of Ptilodus exhibits several specializations for climbing. A survey of postcranial bones of Cretaceous and early Cenozoic multituberculates from North America reveals similar locomotor specializations. Multituberculates possessed distinctive tarsal adaptations for a range of pedal mobility characteristic of arboreal mammals that descend trees headfirst. The divergent hallux could move independently of the other digits. The long robust tail of Ptilodus possessed musculoskeletal features that, among living mammals, are associated with prehensility.     

PALEONTOLOGY: Homoplasy in the Mammalian Ear

The separation of the middle ear bones from the mandible is considered a defining feature of all modern mammals. But did this event happen once in a primitive mammalian ancestor or independently in the monotreme lineage and therian (marsupial and placental) lineage? As Martin and Luo discuss in their Perspective, a new fossil-the dentary bone of an ancient toothed monotreme-suggests that the middle ear bones formed independently in these two mammalian lineages, providing a remarkable example of homoplastic evolution.     

瓯江彩鲤肌间小骨的骨化模式

分别利用形态解剖和整体骨骼染色的方法,对瓯江彩鲤(Cyprinus carpio var.color)成鱼肌间小骨的形态、分布,以及仔、稚鱼肌间小骨的形态发生和出现进行观察。结果表明,瓯江彩鲤肌间小骨有I形、卜形、Y形、一端多叉形、两端两叉形、两端多叉形和树枝形7种类型,肌间小骨越靠前端形态越复杂。肌间小骨出现前,其他骨骼均已骨化完成,肌间小骨在32 dpf(day past fertilization)首先出现在尾部,然后往前依次出现,到53 dpf全部出现。各种复杂形态的肌间小骨均是从I形发展而来。经比较,鲤科不同亚科鱼类肌间小骨在骨化时机和骨化形态方面具有相似的形态发生规律,为今后研究肌间小骨发生的分子机制提供了形态学基础。     

Hind limbs of eocene basilosaurus: evidence of feet in whales

New specimens of middle Eocene Basilosaurus isis from Egypt include the first functional pelvic limb and foot bones known in Cetacea. These are important in corroborating the intermediate evolutionary position of archaeocetes between generalized Paleocene land mammals that used hind limbs in locomotion and Oligocene-to- Recent whales that lack functional pelvic limbs. The foot is paraxonic, consistent with derivation from mesonychid Condylarthra. Hind limbs of Basilosaurus are interpreted as copulatory guides.     

双峰驼后肢骨骼解剖

对5具双峰驼后肢骨骼进行了形态学观察,并与单峰驼、马、牛的后肢骨骼做了比较,发现双峰驼后肢骨骼的特征如下:髋结节薄而窄小,荐结节厚而宽大;坐骨结节粗大,坐骨弓呈深“V”字形;转子窝很深,约3.5cm,无第三转子;膝盖骨呈上下行的椭圆球形;胫骨很发达,其骨干的外侧部较内侧部锐利;腓骨退化,近端只残留一痕迹,远端退化成胫骨远端外侧部下伸的踝突,无骨干;跗骨有6块排成3列。后肢其余的脚骨(跖骨、近趾节骨、中趾节骨和籽骨)较前肢相应的脚骨细、长,亦无远籽骨。     

林麝前肢骨骼解剖

运用大体解剖学方法对三头林麝前肢骨骼进行了研究，并与牛、羊和鹿类的前肢骨骼进行了比较。林麝前肢骨骼的主要特征是：肩胛骨短而宽、肩胛冈特别长，肩峰呈锐角，其末端与肩臼位于同一平面；肱骨近端外侧结节的前部特别发达；前臂骨明显向前弯，只有一个前臂骨间隙，尺骨体呈薄板状；第3和第4掌骨发达，第2和第5掌骨保留远侧部；第3和第4指发达，冠骨和蹄骨较长；第2和第5指较小，每指各有3个指节骨和2个近籽骨。     

食品添加剂Na2 SO3对小鼠嗜多染红细胞微核率的影响

[目的]了解经口进入机体的亚硫酸盐对哺乳动物的毒性效应。[方法]以92只7～12周龄的健康昆明种小鼠为试材, 采用灌胃染毒法进行剂量效应关系和时间效应关系的微核试验。[结果] Na2SO3能诱发小鼠骨髓嗜多染红细胞微核,且随剂量增高微核率明显增加（P＜0.01）。时间效应关系的微核试验表明,Na2SO3染毒后不同时间处死动物并制片,骨髓嗜多染红细胞微核率不同,染毒后12 h的微核率与阴性对照组相比有极显著差异（P＜0.01）,随染毒后时间的延长,细胞微核率增加,24 h达到高峰,与相邻各组差异极显著（P＜0.01）,之后随时间延长而降低,表明Na2SO3诱发小鼠骨髓嗜多染红细胞微核有一定时间效应关系。[结论] 亚硫酸盐是哺乳动物染色体断裂剂和基因毒性因子。     

Temperature acclimation: improved sustained swimming performance in carp at low temperatures

At low temperatures, the reduction in mechanical power output of the aerobic muscle forces cold-blooded animals, such as carp, to recruit their rapidly fatiguing anaerobic fibers at relatively slow swimming speeds. Previous experimental data have suggested that changes in the biochemistry and morphology of the aerobic muscle during cold acclimation might increase its output of mechanical power. The present experiments show that, because of these changes, carp can swim faster at low temperature using only their aerobic muscle, which results in an increase in their sustainable swimming speed. By modifying their musculature, cold-blooded animals can achieve some independence from the effects of seasonal changes in environmental temperature.     

黄河鲤肌间骨发育的形态学观察

采用整体骨骼染色、形态学解剖的方法,对黄河鲤(Cyprinus carpio haematopterus)仔稚鱼肌间骨的形态发生及成鱼肌间骨数目、形态、分布进行研究。结果显示,黄河鲤14 dpf(day post fertilization,体长11.29mm)肌间骨首先在尾部出现,此时其他骨骼包括主轴骨及附肢骨均已骨化完全。伴随鱼体生长,肌间骨由尾向头依次骨化,26 dpf(体长15.60 mm)肌间骨骨化全部完成。黄河鲤肌间骨数在93~104之间,平均为98根;鱼体一侧髓弓小骨平均为34枚,脉弓小骨平均为15枚。黄河鲤肌间骨存在7种形态:"I"形、"卜"形、"Y"形、一端多叉形、两端两分叉形、两端多叉形和树枝形,越靠近鱼体前端肌间骨形态越复杂。研究结果为今后揭示黄河鲤肌间骨骨化的分子机制,培育少肌间骨甚至无肌间骨的黄河鲤提供了形态学基础。     

几种常见鲤科养殖鱼类肌间刺的初步研究

对鲢、鳙、团头鲂和异育银鲫肌间刺的数目、形态和分布进行分析研究，结果显示：鲢的肌间刺数目在117～124之间，鳙的肌间刺数目在116～133之间，团头鲂的肌间刺数目在114～129之间，异育银鲫的肌间刺数目在79～87之间。每条鱼左右两侧的肌间刺数目不完全相等，但总体上两侧肌间刺的数目接近。不同部位的肌间刺数目也有差异：躯干部轴上肌中的肌间刺数目最多，尾部轴上肌与轴下肌中的肌间刺数目基本相等。鲢、鳙、鲫和团头鲂的肌间刺形态都在10种以上。这几种鱼每条鱼的躯干部轴上肌中都有一根很细很短的“l”形刺，这根最短刺的长度在不同规格的鱼上差别并不大。     

几种常见鲤科养殖鱼类肌间刺的初步研究

对鲢、鳙、团头鲂和异育银鲫肌间刺的数目、形态和分布进行分析研究，结果显示：鲢的肌间刺数目在117～124之间，鳙的肌间刺数目在116～133之间，团头鲂的肌间刺数目在114～129之间，异育银鲫的肌间刺数目在79～87之间。每条鱼左右两侧的肌间刺数目不完全相等，但总体上两侧肌间刺的数目接近。不同部位的肌间刺数目也有差异：躯干部轴上肌中的肌间刺数目最多，尾部轴上肌与轴下肌中的肌间刺数目基本相等。鲢、鳙、鲫和团头鲂的肌间刺形态都在10种以上。这几种鱼每条鱼的躯干部轴上肌中都有一根很细很短的“l”形刺，这根最短刺的长度在不同规格的鱼上差别并不大。