Frantsevich Leonid, Wang Weiying
Schmalhausen-Institute of Zoology, B.Chmelnicky str., 15, Kiev-30, 01001, Ukraine.
Arthropod Struct Dev. 2009 Jan;38(1):16-30. doi: 10.1016/j.asd.2008.06.002. Epub 2008 Oct 5.
We studied the common kinematic features of the coxa and trochanter in cursorial and raptorial legs, which are the short size of the podomers, predominantly monoaxial joints, and the approximate orthogonality of adjacent joint axes. The chain coxa-trochanter with its short elements and serial orthogonality of joint axes resembles the gimbals which combine versatility and tolerance to external perturbations. The geometry of legs was studied in 23 insect species of 12 orders. Insects with monoaxial joints were selected. The joint between the trochanter and the femur (TFJ) is defined either by two vestigial condyles or by a straight anterior hinge. Direction of the joint axes in the two basal podomers was assessed by 3D measurements or by goniometry in two planes. Length of the coxa is <15% (mostly <8%) of the total length of the cursorial leg, that of the trochanter <10%. Angles between the proximal and distal joint axes in the middle coxa range from 124 to 84 degrees (mean 97+/-14 degrees ), in the trochanter (in all legs studied) from 125 to 72 degrees (mean 90+/-13 degrees ). Vectors of the distal axis in the coxa are concentrated about the normal to the plane defined by the proximal axis and the midpoint between the distal condyles. These vectors in the trochanter lie at various angles to the normal; angles are correlated with the direction of the TFJ relative to the femur. Range of reduction about the TFJ is over 60 degrees in the foreleg of Ranatra linearis, Mantispa lobata and the hind leg in Carabus coriaceus (confirming observations of previous authors), 40-60 degrees in the foreleg of Vespa crabro and in the middle one in Ammophila campestris, 10-30 degrees in other studied specimens. The special role of the trochanter in autotomy and in active propulsion in some insect groups is discussed. The majority of insects possess small trochanters and slightly movable TFJs with the joint axis laying in the femur-tibia plane. We pose the hypothesis that the TFJ damps external forces, the vectors of which lie off the femur-tibia plane, the reductor muscle acting as a spring. Thus the TFJ contributes to dynamic stability of legged locomotion.
我们研究了疾走型和捕捉型腿部中髋节和转节的共同运动学特征，即肢节短小、主要为单轴关节以及相邻关节轴近似正交。髋节 - 转节链及其短元件和关节轴的连续正交性类似于万向节，兼具通用性和对外界扰动的耐受性。我们研究了12个目的23种昆虫腿部的几何结构。选取了具有单轴关节的昆虫。转节与股骨之间的关节（TFJ）由两个残留髁或一个直的前铰链界定。通过三维测量或在两个平面上进行测角法来评估两个基部肢节中关节轴的方向。在疾走型腿部中，髋节长度小于总长度的15%（大多小于8%），转节长度小于10%。中髋节近端和远端关节轴之间的角度范围为124至84度（平均97±14度），转节（在所有研究的腿部中）为125至72度（平均90±13度）。髋节中远端轴的向量集中在与由近端轴和远端髁之间中点所确定平面的法线附近。转节中的这些向量与法线呈不同角度；这些角度与TFJ相对于股骨的方向相关。在长蝽、螳蛉的前腿以及步甲的后腿中，围绕TFJ的活动范围超过60度（证实了先前作者的观察结果），在胡蜂的前腿和地蜂中间腿中为40 - 60度，在其他研究标本中为10 - 30度。讨论了转节在某些昆虫类群的自切和主动推进中的特殊作用。大多数昆虫的转节较小，TFJ活动轻微，关节轴位于股骨 - 胫节平面内。我们提出假说，即TFJ可衰减外力，这些外力的向量偏离股骨 - 胫节平面，内收肌起到弹簧的作用。因此，TFJ有助于腿部运动的动态稳定性。
