126 



ARTICULATIONS OF THE TRUNK AXD HEAD. 



process. These form the figure of a cross with the transverse ligament, 

 and serve to bind the occiput to the first two vertebrae ; from this arrange- 

 ment is derived the term cruciform, which is sometimes applied to the 

 transverse ligament and its appendages together. 



Fig. 113. TRANSVERSE VER- 

 TICAL SECTION OP THE 



LOWER PART OF THE Oc- 



CIPITAL BONE, AND THE 

 TWO UPPER VERTEBRA 

 BEHIND THE ARTICULA- 

 TIONS (after Arnold). ^ 



1, 1, apparatus ligaraen- 

 tosus and posterior common 

 ligament of the bodies of the 

 vertebrae dissected off the 

 back of the odontoid process, 

 and turned up on the occi- 

 pital bone; 2, 2', vertical 

 part, and 3, 3, transverse 

 or principal part of the cru- 

 cial ligament ; x , neck of 



the odontoid process ; 4, 4, the alar, lateral, check, or occipito-odontoid ligaments ; 

 5, 5, the accessory ligaments of the atlanto-axial capsules, or the lower lateral ligaments 

 of the odontoid process ; 6, 6, part of the capsular ligaments of the condyloid articula- 

 tions ; 7, 7, capsular ligaments of the atlanto-axial articulations ; 8, 8, intertransverse 

 ligaments between the occiput and atlas. 



Two synovial membranes are placed one in front and another behind the 

 odontoid process ; the first of these is situated between the process and the 

 anterior arch of the atlas, the other between the process and the transverse 

 ligament. 



icjg 114 Fig. 114. VIEW OF THE ARTICULATION OF 



THE ODONTOID PROCESS OF THE Axis WITH 

 THE ATLAS, THE UPPER PART OF THE AN- 

 TERIOR ARCH OF THE ATLAS AND THE HEAD 

 OF THE ODONTOID PROCESS HAVING BEEN 



REMOVED BY A HORIZONTAL SECTION. 



1, cut surface of the odontoid process ; 2, 

 cut surface of the anterior arch of the atlas ; 

 3, transverse ligament ; between 1 and 2, the 

 anterior synovial cavity ; between 1 and 3, the 

 posterior synovial cavity of the articulation ; 

 at the sides of the odontoid process, between 

 the anterior and posterior synovial sacs, are 

 seen loose ligamentous fibres ; 4, is placed on 



the back part of the left superior articular process of the atlas : the anterior part of 



this process, and that of the other side, have been partly removed by the section. 



For the sake of distinctness, the synovial spaces are represented somewhat wider than 



natural. 



The odontoid or check ligaments are two thick and very strong bundles of 

 fibres, which extend from the sides of the summit of the odontoid process 

 outwards and a little upwards to be implanted into the rough depression on 

 the inner side of the condyles of the occipital bone, and into a small part of 

 the margin of the foramen magnum. Some of the fibres of the two liga- 

 ments are continuous across the middle line. 



