Anat. and Zool. [f. Gr. ζυγόν yoke + σφήν wedge.] A double wedge-shaped projection on the anterior side of the neural arch of each ordinary vertebra in serpents and some lizards, which fits into the zygantrum of the next vertebra. Hence Zygosphernal a., belonging to or constituting a zygosphene.
1854. Owen, in Orr’s Circ. Sci., Org. Nat., I. 196. A wedge-shaped process (the ‘zygosphene’) … is developed from the fore part of the base of the spine. Ibid., 197. Surfaces to which the zygosphenal surfaces are adapted.
1892. Proc. Zool. Soc., 1 March, 176. The zygosphenes and zygantra of the Ophidian vertebræ.
