SYSTEMATIC SYNTHESIS OF TISSUES INTO ORGANS. 211 



passages through the nose and mouth to the upper part 

 of the throat or pharynx, that extends up in front of the 

 spinal column, and between it and the facium, to the 

 under surface of the cranium. 



297. IT is ALSO WORTHY OF NOTICE HERE that a part 

 (Petrous) of the TEMPORAL bone, in which the internal 

 ear is wrought, is connected by an arm with the facium 

 (Fig. 1, PL 9), and, properly speaking, is to be counted 

 as a part of it. 



298. THE PETROUS is FORMED distinct from t the 

 temporal bone, and afterwards, in man, consolidates with 

 it, though it does not in all animals ; and as it con- 

 tains organs of sense, and is constructed with reference 

 to them, it is to be classed with the facium, constructed 

 for similar reasons. 



299. THE EIGHT BONES OF THE EAR MAY BE DE- 

 SCRIBED in connection with that organ. 



300. THE SKULL NEEDS BUT TWO MOVABLE JOINTS, 

 similar, since they unite the lower jaw to its sockets. 



FIG. 162. 



Fig. 162 represents the joint of the 

 lower jaw, that is very curious on ac- 

 count of the friction cartilage 6, intro- 

 duced in the joint at 3, there being a 

 lubricating space above and below it. 

 This is required on account of the great 

 and frequent pressure produced here in 

 eating. 



301. Remark. SOMETIMES in gaping this bone slips forward, and 

 the jaw cannot be raised. Press the back part of the jaw down and 

 backward with sufficient force to carry it into place. 



302. Inf. Very little CARTILAGE OR gristle, very little SINEWY TIS- 

 SUE in the form of ligaments, is REQUIRED BY the construction of THE 



SKULL. 



29T. What ? 299. How ? 299. When ? 300. What ? Describe Fig. 

 162. 801. What the effect of gaping ? 802. What ? 



