110 



LIGAMENTS OP THE LOWER JAMf. 



its position by the transverse ligament, when the other ligaments are 

 cut through. The extent to which the rotation of the head upon the 

 axis can be carried is determined by the odontoid ligaments. The 

 odontoid process with its ligaments is covered in by the occipito- 

 axoid ligament. 



5. Articulation of the Lower Jaw. The lower jaw has properly 

 but one ligament, the external lateral; the ligaments usually described 

 are three in number ; to which may be added, as appertaining to the 

 mechanism of the joint, an interarticular fibre-cartilage, and two 

 synovial membranes : v 



External lateral, 



Internal lateral, 



Capsular. 



Interarticular fibro-cartilage, 

 Two synovial membranes. 



Fig. 46 * 



The external lateral ligament is a short and thick band of fibres, 

 passing obliquely forwards from the tubercle of the zygoma, to the 



external surface of the neck of the 

 lower jaw. It is in relation, exter- 

 nally with the integument of the 

 face, and internally with the syno- 

 vial membranes of the articulation,, 

 and with the interarticular fibro-car- 

 tilage. The external lateral ligament 

 acts conjointly with its fellow of the 

 opposite side of the head in the move- 

 ments of the jaw. 



The internal lateral ligament has 

 no connexion with the articulation 

 of the lower jaw, and is incorrectly 



named in relation to the joint ; it is a thin aponeurotic expansion 

 extending from the extremity of the spinous process of the sphenoid 

 bone to the margin of the dental foramen. It is pierced at its inser- 

 tion, by the mylo-hyoidean nerve. 



A triangular space is left between the internal lateral ligament and 

 the neck of the jaw, in which are situated the internal maxillary 

 artery and auricular nerve, the inferior dental artery and nerve, and 

 a part of the external pterygoid muscle ; internally it is in relation 

 with the internal pterygoid. 



The capsular ligament consists of a few irregular ligamentous 

 fibres, which pass from the edge of the glenoid cavity to the neck 

 of the lower jaw, upon the inner and posterior side of the articula- 



* An external view of the articulation of the lower jaw. 1. The zygomatic arch. 

 2. The tubercle of the zygoma. 3. The ramus of the lower jaw. 4. The mastoid 

 portion of the temporal bone. 5. The external lateral ligament. 6. The stylo-maxil- 

 lary ligament. 



