THE BONES OF THE HEAD 



119 



The condyle surmounts the posterior border of the ramus. It 

 is oval and convex, and it articulates with the anterior part of the 

 glenoid fossa of the temporal, an interarticular fibro - cartilage 

 inter\-ening. Its long axis is oblique, so that the axes of the two 

 condvles, if sufficiently prolonged inwards and slightly backwards, 

 would meet near the anterior margin of the foramen magnum. 

 Extemallv the condyle presents a projection, called the condylar 

 tubercle, for the external lateral ligament of the temporo-mandi- 

 bular articulation. Below the condyle is the neck, which presents 

 anteriorly a depression for the inser- 

 tion of the greater part of the 

 external pter\'goid muscle. 



The bone receives its chief blood- 

 supply from the inferior dental branch 

 of the internal maxillary artery. 

 Other sources are the facial, and the 

 sublingual branch of the lingual. 



Articulations. — With the glenoid 

 fossae of the temporal bones. 



Structure. — ^The inferior maxilla is 

 composed of two dense plates of compact bone, which are particu- 

 larly strong in the region of the base, but become thinner superiorly 

 at the alveolar border. Between these plates there is cancellated 

 tissue with wide meshes. 



Ossification. — The mandible is a mixed bone, being chiefly a membrane 

 bone, but in part also a cartilage bone. It is ossified in connection with 

 Meckel's cartilage and its fibrous investment. Each half of the bone has 

 one centre (Low and Fawcett), which appears about the sixth week of intra- 



Coronoid Process 



Fig. 74A, — The Inferior 

 Maxill.\ry Bone at Birth. 



Mai leas 



Alveolar Groove 



Hamulus 



^3 _Tym panic 

 .'\nnulus 



and 

 Membrane 



Mecke^^ Cartilage 



Manubrium of Malleus Long Process of Incus 



Fig. 74B. — Meckel's Cartil.\ge. {From Keibel .\nd Mall. After 



KotLM.\NN). 



uterine hfe, being only preceded by the primary centres for the cla\icle. 

 It is deposited in the membrane which covers the outer surface of Meckel's 

 cartilage in the region of the future mental foramen. From this centre one- 

 half of the bone is ossified, chiefly in membrane, but also in cartilage, namely, 

 the mesial end of Meckel's cartilage, and certain other accessory cartilages. 

 The original centre gives membranous origin to (i) the walls of the alveoli and 



