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Biomedical subjects

J P Gasc

Publications and source records attributed to J P Gasc.

8 recordsLinked to original sources

[The mechanism of digging in Arvicola terrestris and Spalax ehrenbergi: functional and evolutional studies].

The cineradiographic study of the digging modalities in Arvicola terrestris and Spalax erenbergi showed important convergences in the mechanisms used by both species. Head and incisors are the burrowing tools, acting as a "scraping-shovel" in Spalax and as a "scratching-shovel" in Arvicola. They are moved forward by a force originated by the pressure of the hind limbs against the ground, and transmitted through the vertebral axis. The myological study of these species revealed the increase of the insertional areas for the cephalic muscles. However, the adaptative answer of the cervical vertebrae to the mechanical constraints of digging are different in Arvicola and Spalax; the former developed high resistance moments and the latter increased vertebral stiffness. The characters of the post-cranial skeleton in the digging rodents tend to constitute a morphocline in which Spalax is the final stage and Arvicola an intermediate stage. Then, the adaptative divergences noted above between these animals might reflect their phyletic distance.

Animals

Patterns of correspondence between skin rings and vertebrae in gymnophiona (Amphibia).

The skin annulation seems to have a direct relation with the vertebral column segmentation. The type of rings, primary, secondary, tertiary, or quaternary set by binary division, probably results in an induction process during morphogenesis. The diverse stages of this division appear and are rubbed out from front to rear. The topographical correspondence is different for 3 distinct parts of the body: the collar, the trunk, and the posterior part. In this last region, we can find a more or less reduced true tail or a terminal appendage without vertebral element. All these new morphological data support elements of functional indications.

Amphibians

Preliminary note on biometric data relating to the human coraco-acromial arch.

A biometric study based on 20 human scapulae made it possible to specify the variations in the gap of the coraco-acromial arch in relation to its depth and height. A graphic representation in rectangular coordinates, then in spatial representation in relation to the three planes of reference, leads to the following findings: the bony variations in the arch occur essentially: at the coracoid apophysis, and two types of arch can be distinguished depending on the predominance of bony or of ligamentous components.

Acromion

[Synchronization of electromyographic and cinematographic recordings. Applications to vertebrate biomechanics].

Synchronizing each frame of the cinema of a moving animal with the corresponding EMG of some muscles permits a precise interpretation of the variations of the electric potentials in that muscle with each phase of the movement. e.g. in the rabbit, three bundles of the masseter muscle function independently during the mastication; in the pigeon, electric potentials appear in both ilio-tibialis and biceps femoris muscles some frames before the actual raising of the leg, when the animal on its perch becomes out of balance.

Animals