LIGAMENTS OF THE LCWER JAW. 



143 



The external lateral ligament is a short r,nd thick band of fibres, pass 

 311? obliquely backwards from the tubercle of the zygoma, to the external 

 surface of the neck of the lower jaw. It is in relation, externally with the 

 integument of the face, and internally with the two synovia! membranes 

 of the articulation and the iriterarticular cartilage. The external lateral 

 ligament acts conjointly with its fellow of the opposite side of the head in 

 the movements 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 pro- 

 cess of the sphenoid bone to the margin of the dental foramen. It is 

 pierced at its insertion, by the mylo-hyoidean nerve. 



Fig. 79 * 



Fig. 80.f 



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 ex- 

 ternal pterygoid muscle ; internally it is in relation with the internal ptery- 

 goid muscle. 



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 articulation. These fibres 

 scarcely deserve consideration as a distinct ligament. 



The inter articular fibrous cartilage is a thin oval plate, thicker at the 

 edges than in the centre, and placed horizontally between the head of the 

 condyle of the lower jaw and the glenoid cavity. It is connected by its 

 outer border with the external lateral ligament, and in front receives some 

 fibres of the external pterygoid muscle. Occasionally it is incomplete in 

 the centre. It divides the joint into two distinct cavities, the one being 

 above and the other below the cartilage. 



The synovial membranes are situated the one above, the other below, 

 the fibrous cartilage, the former being the larger of the two. When the 

 fibrous cartilage is perforate, the synovial membranes communicate. 



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

 2. The tubercle of the zygoma. 3. The ram us of the lower jaw. 4. The mastoid por 

 tion of the temporal bone. 5. The external lateral ligament. 6. The stylo-maxillary 

 .igament. 



j- An internal view of the articulation of the lower jaw. 1. A section through the pe- 

 trous portion of the temporal bone and spinous process of the sphenoid. 2. An internal 

 view of the ramus, and part of the body of the lower jaw. 3. The internal portion of 

 the capsular ligament. 4. The internal lateral ligament. 5. A small interval at its in 

 sertion, through which the mylo-hyoidean' nerve passes. 6. The stylo-maxillary iiga 

 ment, a process of the deep cervical fascia. 



