132 



ARTICULATIONS OF THE TRUNK AND HEAD. 



muscles. It is sufficient at present to state that the elevation and rotation of the 

 ribs in inspiration are the main causes of the antero-posterior and transverse enlarge- 

 ment of the chest. The angular movement is greatest in the upper and least in the 

 lowest ribs. 



TEMPOfcO-MAXILLARY ARTICULATION. 



The lower jaw articulates by its condyle on each, side with, the smooth 

 surface of the temporal bone, extending over the part of the glenoid fossa 



Fig. 121. 



Fig. 121. A PORTION OP THE 



SKULL AND LOWER JAW WITH 

 HALF THE HYOID BONE, SEEN 

 FROM THE RIGHT AND OUTER 

 SIDE (after Arnold). ^ 



1, the external lateral ligament 

 of the temporo-maxillary articula- 

 tion ; 2, a part of the capsular 

 ligament of the joint ; 3, styloid 

 process; 4, stylo-maxillary liga- 

 ment ; 5, stylo-hyoid ligament ; 

 6, the lesser cornu of the hyoid 

 bone with some short ligaments 

 attaching it to the body and great 

 cornu ; 7, the body ; 8, the ex- 

 tremity of tbe great cornu. 



in front of the Glaserian 

 fissure and the anterior root 

 of the zygoma. The joint is 

 divided by an interarticular 

 nbro-cartilage into an upper 

 and a lower synovial cavity. 

 The external lateral ligament is a short fasciculus of fibres, attached 



Fig. 122. A PORTION OF THE SKULL 



AND LOWER JAW WITH HALF THE HYOID 

 BONE, SEEN FROM THE INSIDE. 



The indications where marked are the 

 same as in Fig. 121 ; the styloid process, 

 3, is detached from the skull ; the body of 

 the hyoid bone, 7, is represented as cut 

 through in the middle, so tbat tbe posterior 

 and inner surface of the right half of the 

 bon is seen ; 9, the internal lateral liga- 

 ment of the temporo-maxillary joint ; 10, 

 the upper opening of the inferior maxillary 

 canal. 



above to the external surface and the 

 tubercle of the zygoma ; and below, 

 to the external surface and poste- 

 rior border of the neck of the 

 lower jaw, its fibres being directed 

 downwards and backwards. Thin 

 and short additional ligamentous 



fibres cover the synovial membrane and form an irregular capsule round 



the joint. 



