Russian J. Theriol. 1 (2): 91109 © RUSSIAN JOURNAL OF THERIOLOGY, 2002 Cinefluorographical study of the burrowing movements in the common mole, Talpa europaea (Lipotyphla, Talpidae) Petr P. Gambaryan, Jean-Pierre Gasc & Sabine Renous ABSTRACT. The burrowing process of the common mole Talpa europaea Linnaeus, 1758 was investigated by the cinefluorography. During burrowing the humerus is abduced only on 2530°. This abduction is realized by the rotation of the scapula around its longitudinal axis and by the translation of the clavicle in the sternoclavicular and claviculohumeral joints. The abduction of the shoulder joint is limited to 1015° by nearly complete coincidence of the articular surfaces of the scapular glenoid fossa and the humeral head. The shoulder joint extension diminishes the abductors momentum on 3070% and in this case they cannot develop the force determined in the experiments. M. flexor digitorum profundus is transformed in the ligament which origins on the median epicondyle of humerus and inserts on all the five ungual phalanges. This is an unique mechanism for the neutralization pronation momentum of the humerus abductors. The increasing of the pressure of the hands on the soil augments the tension of the m. flexor digitorum profundus what hinders the pronation of the humerus. The increasing of the rotation of the antebrachium is necessary to maintain the hand in a parasagittal plane. An accretion of the humeral median epicondyle promotes decreasing of the humerus rotation. Humerus rotates during terrestrial locomotion in all tetrapods with sprawling limb position (humerus pronates in the propulsive phase and supinates in the swing phase). The recent Monotremata and probably primitive mammals use the humerus pronation for the lengthening of the stride. Mm. supraspinatus and infraspinatus prevent the humerus retraction. The widening of the humerus in these mammals is an adaptation to its rotation by the limited abduction and retraction. On the contrary, the widening of humerus in moles is an adaptation to its abduction by the limited rotation. Thus the convergent widening of the humerus in these animals is caused by the diametrically opposite functions. KEY WORDS: Talpa europaea, cinefluorography, biomechanical analysis, burrowing. Petr P. Gambaryan [[email protected]], Zoological Institute, Russian Academy of Sciences, Univer- sitetskaya nab.1, Saint Petersburg 199034, Russia; Jean-Pierre Gasc [[email protected]], URA 1137 Labora- toire dAnatomie comparée, Muséum national dHistoire naturelle, 55 rue Buffon, 75231 Paris Cedex 05, France; Sabina Renous, URA 1137 Laboratoire dAnatomie comparée, Muséum national dHistoire naturelle, 55 rue Buffon, 75231 Paris Cedex 05, France. Êèíîðåíãåíîñêîïè÷åñêîå èññëåäîâàíèÿ ðûòüÿ îáûêíîâåííîãî êðîòà, Talpa europaea (Lipotyphla, Talpidae) Ï.Ï. Ãàìáàðÿí, Æ.-Ï. Ãàñê, Ñ. Ðåíî ÐÅÇÞÌÅ. Ñ ïîìîùüþ êèíîðåíãåíîñêîïèè èçó÷àëîñü ðûòüå îáûêíîâåííîãî êðîòà Talpa europaea Linnaeus, 1758. Ïðè ðûòüå ïëå÷î àáäóöèðóåòñÿ òîëüêî íà 2530°. Àáäóêöèÿ îáåñïå÷èâàåòñÿ âðàùå- íèåì ëîïàòêè âîêðóã åå äëèííîé îñè è ïåðåìåùåíèåì êëþ÷èöû â ãðóäîêëþ÷è÷íîì è êëþ÷è÷íîïëå- ÷åâîì ñóñòàâàõ.  ñâÿçè ñ ïî÷òè ïîëíûì ñîâïàäåíèåì ñóñòàâíûõ ïîâåðõíîñòåé ãëåíîèäíîé ÿìêè ëîïàòêè è ãîëîâêè ïëå÷à, àáäóêöèÿ â ïëå÷åâîì ñóñòàâå îãðàíè÷èâàåòñÿ 1015°. Åñëè âðàùåíèå ïëå÷à áóäåò óâåëè÷èâàòüñÿ, òî àáäóêòîðíûé ìîìåíò îñíîâíûõ àáäóêòîðîâ áóäåò óìåíüøàòüñÿ. Èç-çà ðàçãèáàíèÿ ïëå÷åâîãî ñóñòàâà ìîæåò ðåçêî ñîêðàùàòüñÿ àáäóêòîðíûé ìîìåíò (íà 3070%); â ýòîì ñëó÷àå íå ñìîæåò ðàçâèâàòüñÿ ñèëà, êîòîðóþ ìû ýêñïåðèìåíòàëüíî îïðåäåëèëè. M. flexor digitorum profundus ïðåâðàùåí â ñóõîæèëèå, êîòîðîå íà÷èíàåòñÿ íà ìåäèàëüíîì íàäìûùåëêå ïëå÷à è îêàí÷è- âàåòñÿ íà âñåõ ïÿòè êîãòåâûõ ôàëàíãàõ. Ýòà óíèêàëüíàÿ êîíñòðóêöèÿ ñëóæèò äëÿ íåéòðàëèçàöèè ïðîíàòîðíîãî ìîìåíòà àáäóêòîðîâ ïëå÷à. Âîçðàñòàíèå äàâëåíèÿ êèñòÿìè íà ïî÷âó ïðèâîäèò ê íàïðÿæåíèþ m. flexor digitorum profundus, êîòîðûé ïðåïÿòñòâóåò ïðîíàöèè ïëå÷à. Äëÿ ïîääåðæàíèÿ êèñòåé â ïàðàñàãèòòàëüíîé ïëîñêîñòè íåîáõîäèìî óâåëè÷åíèå âðàùåíèÿ ïðåäïëå÷üÿ. Ðàçðàñòàíèå ìåäèàëüíîãî íàäìûùåëêà ïëå÷à ñïîñîáñòâóåò óìåíüøåíèþ âðàùåíèÿ ïëå÷à. Âî âðåìÿ íàçåìíîé ëîêîìîöèè ïëå÷î âðàùàåòñÿ ó âñåõ òåòðàïîä ñ ðàññòàâëåííûì ïîëîæåíèåì êîíå÷íîñòåé (ïëå÷î ïðîíèðóåò â ïðîïóëüñèâíîé ôàçå è ñóïèíèðóåò â ïåðåíîñíîé ôàçå). Ó ñîâðåìåííûõ îäíîïðîõîäíûõ è, âåðîÿòíî, ó ïåðâè÷íûõ ìëåêîïèòàþùèõ ïðîíàöèÿ ïëå÷à ñëóæèëà äëÿ óâåëè÷åíèÿ äëèíû øàãà. Mm. supraspinatus è infraspinatus ïðåïÿòñòâîâàëè ðåòðàêöèè ïëå÷à. Ðàñøèðåíèå ïëå÷à ó ïðèìèòèâíûõ ìëåêîïèòàþùèõ - àäàïòàöèÿ ê âðàùåíèþ ïëå÷à ïðè îòñóòñòâèè åãî ðåòðàêöèè è àáäóêöèè. Íàîáîðîò, ó êðîòîâ ðàñøèðåíèå ïëå÷à ñâÿçàíî ñ àäàïòàöèåé ê ñîêðàùåíèþ âðàùåíèÿ ïðè óâåëè÷åíèè åãî àáäóêöèè. Êîíâåðãåíòíîå ðàñøèðåíèå ïëå÷à â ýòîì ñëó÷àå âîçíèêàåò â ñâÿçè ñ ïðèñïîñîáëåíèåì ê äèàìåòðàëüíî ïðîòèâîïîëîæíûì ôóíêöèÿì. ÊËÞ×ÅÂÛÅ ÑËÎÂÀ: Talpa europaea, êèíîðåíãåíîñêîïèÿ, áèîìåõàíè÷åñêèé àíàëèç, ðûòüå. 92 Petr P. Gambaryan, Jean-Pierre Gasc & Sabine Renous Introduction directed backward and downward in most other mam- mals. Theoretically such position of the humerus might The process of burrowing includes the substrate be attained through hyperextension or hyperabduction. loosening and throwing of the ground out of a tunnel, In Talpidae it is undoubtedly due to the hyperabduction actions, which need a great amount of energy. Thus, since the medial epicondyle is situated laterally, where- adaptations to a subterranean mode of life, involving the as the lateral one is facing medially, and the caput humeri excavation of long tunnels for feeding and other aspects keeps its position on the dorsal surface of the bone. of the life history, affect skeletal and muscular structures Therefore, the mole, abduction, i.e. the moving of the (Hildebrand, 1985). Among the most highly specialized distal end of the arm away from parasagittal plane, diggers, the representatives of the family Talpidae, corresponds to the action of adductor muscles. The specifically Talpa europaea Linnaeus, 1758, exemplify flexion of the shoulder joint is unusual also. Flexion of a unique mode of burrowing where both components of this joint in mole reduce the distance between cranial the burrowing process are united into a single movement border of the scapula and humerus (unlike the flexion in (Gambaryan, 1960), realizing the so called lateral thrust other mammals, which reduce the distance between the method of digging (Reed, 1951). caudal border of the scapula and humerus) and could be The definition of certain descriptive terms is neces- designated as hyperextension. sary since the mole forelimb skeleton is peculiar in Consequently anatomical dorsal surface of the hu- comparison to that of other mammals. The distal end of merus is directed cranially, and the volar one caudally. the mole humerus is directed forward and upward (Figs. The longitudinal axis of the humerus and its plane usually 13) with respect to the shoulder joint whereas it is lie vertical (Figs. 2, 3). During lateral thrust a little Figure 1. Mole, Talpa europaea, digging in dorsal view. Several successive positions (I to VI) of forelimbs during the removal of the soil drew from the cinefluorographic film taken at 60 frames per second. The arrows A indicate sum vectors forces of the muscles taking place in movement in claviculohumeral joint (O). Length of the vectors are proportional to physiological section of the muscles. B, C, and D are representing pressing force of the hand: B 120°, C 90°, D 60° to the sagittal plane (C is a usual direction pressing force of the hand; B and D are the extreme directions of the pressing force). Solid line force moment; dotted line direction of the force vectors. Burrowing in Talpa 93 94 Petr P. Gambaryan, Jean-Pierre Gasc & Sabine Renous Figure 2. Lateral view of Talpa europaea skeleton syndesmological preparation in positions corresponding to those on the frames IVI (Fig 1). This view shows the flexio-extension in shoulder and elbow joints, not seen in dorsal view (Fig. 1). Figure 3. Mole, Talpa europaea, digging in lateral view. Several successive positions (I to IV) of forelimbs drew from the cinefluorographic film taken at 60 frames per second. rotation of the humerus shifts the medial epicondyle (Reed, 1951; Gambaryan, 1960). Graphical analysis of caudolaterally, and the lateral one craniomedially. static equilibrium (Nikolskii, 1978) revealed the adap- Many investigators described the mole skeleton and tive significance of some structural features in the mole. muscles (e.g., Dobson, 1882; Todorowa, 1927; Ed- However, a detailed analysis of the burrowing process wards, 1937; Reed, 1951; Gambaryan, 1960; Yalden, has not been undertaken yet. Cinefluorography is the 1966; Castiella et al., 1992). In some of these works the most precise method to study the movements of the influence of the burrowing on the structure of the skel- skeleton and to analyze muscles functioning. Some eton and muscles was discussed. Sometimes, quantita- fossorial forms have been studied by this method, in- tive parameters of the muscles were taken into account cluding Eremitalpa granti (Broom, 1907) (Gasc et al., Burrowing in Talpa 95 1986), Arvicola terrestris (Linnaeus, 1758) (Laville, 1988), and Myospalax myospalax (Laxmann, 1773) (Gambaryan & Gasc, 1993). In the present paper we discuss the results of the cinefluorographical study of the burrowing in Talpa europaea. Despite of the detailed description of muscles in Talpa europaea, the forces, which can be exerted by its forelimbs, are not estimated yet. The aims of our inves- tigation were: