13S 



AETICULATIONS OF THE TRUNK AND HEAD. 



nrticnlar surfaces of the axis and with the condyles of the occipital bone. 

 The atlanto-axial capsule is strengthened behind by an accessory liga- 

 ment, directed downwards and inwards to the body of the axis near the 

 base of the odontoid process. 



The transverse ligament of the atlas is a strong and thick 

 band, which extends across the ring of the atlas, and retains the odon- 

 toid process in its place. It is attached on each side to the tubercle 

 below the inner border of the superior articulating process. It is arched 

 backwards behind the odontoid process, and is broadened out in the 

 middle line. From the middle of its posterior surface a short thin 

 bundle of fibres passes down to be attached to the body of the axis, 

 whilst another passes up to the basilar process. These form, vdth the 

 transverse portion, the figure of a cross, and serve to bind the occiput 

 to the first two vertebra3 ; from this arrangement is derived the term 

 cruciform, which is sometimes applied to the transverse ligament and 

 its appendages together. 



Fi-. 122. Fig. 122.— TuANSvERSE Ver- 



tical Section of the 



1 LOWER PART OF THE Oc- 



cii'iTAL Bone, and the 



TWO LTPER YeRTEBR.E 



BEniND THE Articula- 

 tions (A. T. after Arnold). 



1, 1, apparatus ligamen- 

 tosTis tui-ned up on the occi- 

 jiital hone ; 2, 2', vertical 

 l^art, and 3, 3, transverse 

 or principal i)art of the cru- 

 ciform ligament ; x , neck 

 of the odontoid process ; 4, 

 4, the alar or lateral odon- 

 toid ligaments ; 5, 5, the 

 accessory ligaments of the 



atlanto-axial capsules ; 0, G, part of the capsular ligaments of the condylar articulations ; 



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



tetweeu 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 



Fig. 123. 



Fig. 123.- — Horizontal Section throVgh the 

 Odonto-Atlantal Articulation. (A. T.) i 



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, and between 1 and 3, the 

 posterior synovial cavity of the articulation ; 4, is 

 placed on the back part of the left superior ai-ti- 

 cular 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. 



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

 and the transverse ligament. 



