The Peculiarities Of The Spinal Column Joints At Muskrat (Ondatra Zibthica)

摘要

The mobility of the muskrat head is determined by the massive cervical muscles and the particularity of the joints and the bones structures. Considering the dorso-ventral flatting of the cervical vertebrae C3-C7, the long transverse processes, the presence of joints between the transvers processes of the vertebrae C5-C6, C6-C7, the jointing surface like aZ between the jointing processes of cervical vertebra and that the first ribs is jointed with the transverse process of C7 vertebra may show that the cervical vertebrae produce a complex rigid, the neck movements are products only of the occipito-atlanto-axial jointing complx. At muskrat, each of two occipital condyles consists of two sub-units separated by an articular notch: a classic biconvex condyl lateral placed, and a capitulum, ventro-medially. During the head flexion, the angle between the head and cervical region is about 900, and is condyl occipital is articulated with the atlas through the capitulum (subunits of the occipital condyle) so that movement possible is flexion, extension, and especially for side widening area visual and audible. Conformation of the bones and articular structures of the lumbar region of the muskrat shows increased mobility, the flexion and the extension is mainly due to large areas of joint of the jointing process joints. The region of the tail is highly mobile, being used for body direction during the swimming.