What is "quadrate bone"

Quadrate \Quad"rate\, a. [L. quadratus squared, p. p. of quadrare to make four-cornered, to make square, to square, to fit, suit, from quadrus square, quattuor four. See Quadrant, and cf. Quadrat, Quarry an arrow, Square.]

1. Having four equal sides, the opposite sides parallel, and four right angles; square.

   Figures, some round, some triangle, some quadrate.
   --Foxe.

2. Produced by multiplying a number by itself; square. `` Quadrate and cubical numbers.''
   --Sir T. Browne.

3. Square; even; balanced; equal; exact. [Archaic] `` A quadrate, solid, wise man.''
   --Howell.

4. Squared; suited; correspondent. [Archaic] `` A generical description quadrate to both.''
   --Harvey.

   Quadrate bone (Anat.), a bone between the base of the lower jaw and the skull in most vertebrates below the mammals. In reptiles and birds it articulates the lower jaw with the skull; in mammals it is represented by the malleus or incus.

n. (context anatomy English) A bone between the base of the lower jaw and the skull in most vertebrates other than mammals. In reptiles and birds it articulates the lower jaw with the skull; in mammals it is represented by the incus.

The quadrate bone is part of a skull in most tetrapods, including amphibians, sauropsids ( reptiles, birds), and early synapsids. In these animals it connects to the quadratojugal and squamosal in the skull, and forms part of the jaw joint (the other part is the articular bone at the rear end of the lower jaw).

It is formed by endochondral ossification and is formed from the hindmost part of the primitive cartilaginous upper jaw.