Peculiarities of thorax intervertebral joints in muskrat (Ondatra zibethica)

The transverse process of thorax vertebra had a different conformation in the muskrat’s case. This process was completely formed in the first three and the last two thoracic vertebra (the lamina separated from the body is knitted with the one separated from the arch). Starting with the fourth vertebra until the eleventh one, the transverse process was incomplete. Between the two laminas, a deep incision was created. The lamina separated from the body was changed in an articulatory process, made up of two surfaces: a lateral (ventral) one, of articulation with the tubercle of the rib, and a medial (dorsal) one. The transverse incision was used for sliding like on a trochlea of the costal-transverse intraarticular ligament, which was specific to the muskrat, for the insertion in the back of the incision