Zygosphene-zygantrum articulation

The Zygosphen Zygantrum - joint is an additional joint between the vertebrae, which occurs from the group of Lepidosauromorpha at various reptiles. This pivot joint is formed by a forward wedge- like appendage, the Zygosphen that fits in a back recess of the preceding vertebra, the Zygantrum. The Zygosphen located between the prezygapophyses on the front of the vertebral arch, while the Zygantrum between postzygapophyses sitting on the back of the vertebral arch.

This joint occurs in snakes, lizards rights, rail lizards, Zwergtejus and in some iguanas and belt tails. Less pronounced, it is also present in the tuatara. In addition, it is found in some purely fossil groups such as the plesiosaurs, the Nothosauriern and Pachypleurosauriern. It is missing in today's lizards, but was present in fossil representatives of this group.

The Zygosphen - Zygantrum joint serves to stabilize the spine. It allows horizontal and vertical movements of the spine, but prevents twisting the individual vertebrae against each other.

Documents

• Joint
• Anatomy of Reptiles