34 ANATOMY OF THE DOMESTIC FOWL 



ma tic, lying at the outer side of the upper jaw. They have been 

 described under zygomatic, which see. 



The Quadrate. Location. The quadrate bones, or ossa quadra ta, 

 two in number, are located antero-laterally to the temporal bones. 

 Each articulates inferiorly with the posterior articular portion, or 

 pars articulare, of the inferior maxilla and infero-laterally with 

 the quadrato-jugalare portion of the zygomatic. It articulates 

 antero-internally with the pterygoid and supero-posteriorly with 

 the temporal. 



Description. The quadrate bone is anvil-like in shape. It 

 has an anterior process, the orbital process, for muscular attach- 

 ments, and posteriorly it affords attachment to the ear drum. 



The Inferior Maxilla. Location. The inferior maxilla, lower jaw, 

 or os maxillare inferius, also called the mandibular bone, or pars 

 dentis, is analogous to the lower jaw of mammals. It articulates 

 posteriorly with the quadrate bone. 



Description. The inferior maxilla is the largest bone of the face. 

 It is made up of a right and a left limb which are separate in the fetus 

 and which unite subsequently anteriorly, forming the inferior por- 

 tion of the beak. Each limb of the jaw is developed from five ele- 

 ments: the pars articularis, which forms the jaw-joint and, expanded, 

 articulates with the quadrate bone; the pars angularis, lying just in 

 front of the pars articularis ; the pars supra-angularis, a slender bone 

 lying just above the angularis; the splenial, a thin plate of bone, 

 lying along the inner surface of the mandible; and the pars dentalis, 

 which forms the anterior portion of the jaw. 



The Turbinate Bones. Location. The turbinate bones, or ossa 

 turbinata, six in number, are attached to the lateral walls of the 

 nasal cavity (Fig. 26, No. A, i and 2). In each nasal cavity there are 

 three turbinate bones, one anterior and two posterior. Of the two 

 posterior the upper one lies supero-posterior to the inferior one. 

 The turbinate bones are attached to the lateral nasal walls, project 

 into the cavity and thus greatly diminishing its extent. 



Description. Each turbinate bone is composed of a very thin 

 lamina, finely cribriform in many places, and in the fresh state, 

 covered on both sides with mucous membrane. These bones are 

 curled and partly membrano-cartilaginous structures which give 

 greater surface in the nasal passage for mucous membrane in which 

 the olfactory nerve terminal filaments are distributed. 



