LIGAMENTS OF THE VERTEBRAL COLUMN. 109 



Anterior atlo-axoid. Two capsular. 



Posterior atlo-axoid. Transverse. 



The anterior ligament consists of ligamentous fibres, which pass 

 from the anterior tubercle and arch of the atlas to the base of the 

 odontoid process and body of the axis, where they are continuous 

 with the commencement of the anterior common ligament* 



The posterior ligament is a thin and membranous layer, passing 

 between the posterior arch of the atlas and the laminae of the axis. 



The capsular ligaments surround 

 the articular processes of the atlas Fi g- 45 -t 



and axis ; they are loose, to permit 

 of the freedom of movement which 

 subsists between the atlas and axis. 

 The ligamentous fibres are most 

 numerous on the outer and anterior 

 part of the articulation, and the 

 synovial membrane usually commu- 

 nicates with the synovial cavity be- 

 tween the transverse ligament and 

 the odontoid process. 



The transverse ligament is a strong ligamentous band, which 

 arches across the area of the ring of the atlas from a rough tubercle 

 upon the inner surface of one articular process to a similar tubercle 

 on the other. It serves to retain the odontoid process of the axis 

 in connexion with the anterior arch of the atlas. As it crosses the 

 odontoid process, some fibres are sent downwards to be attached to 

 the body of the axis, and others pass upwards to be inserted into 

 the basilar process of the occipital bone ;J hence the ligament has a 

 cross-like appearance, and has been denominated cruciform. A 

 synovial membrane is situated between the transverse ligament and 

 the odontoid process ; and another between that process and the 

 inner surface of the anterior arch of the atlas. 



Actions. It is the peculiar disposition of this ligament in relation 

 to the odontoid process, that enables the atlas, and with it the entire 

 cranium, to rotate upon the axis ; the perfect freedom of movement 

 between these bones being ensured by the two synovial membranes. 

 The lower part of the ring, formed by the transverse ligament with 

 the atlas, is smaller than the upper, while the summit of the odontoid 

 process is larger than its base ; so that the process is still retained in 



* Usually considered a part of the anterior vertebral ligament. G. 



t A posterior view of the ligaments connecting the atlas, the axis, and the occipital 

 bone. The posterior part of the occipital bone has been sawn away, and the arches of 

 the atlas and axis removed. 1. The superior part of the occipito-axoid ligament, 

 which has been cut away in order to show the ligaments beneath. 2. The transverse 

 ligament of the atlas. 3, 4. The ascending and descending slips of the transverse liga- 

 ment, which have obtained for it the title of cruciform ligament. 5. One of the odon- 

 toid ligaments. 6. One of the occipito-atloid capsular ligaments. 7. One of the atlo- 

 axoid capsular ligaments. 



t These bands are called the appendices of the transverse ligament. G. 



