LIGAMENTS OF ATLAS AND AXIS. 



167 



The ligaments outside the spinal canal are thin fibrous membranes, 

 which connect the bodies and arches of the first two vertebrae in front and 

 behind; and join the atlas with the occipital bone at the same aspects. 



Fig. 46. 



EXTERNAL LIGAMENTS IN FRONT BETWEEN THE ATLAS AND Axis AND THE 

 OCCIPITAL BONE (Bourgery). 



1. Sawn basilar process. 3. Anterior atlo-axoid. 



2. Anterior occipito-atloid. 4. Articulation of the articular processes cut open. 



Capsular ligaments surround the articular surfaces of all the bones; but 

 these will be examined more conveniently after the spinal canal has been 

 opened. 



Union of the atlas with the axis. The posterior ligament (atlo-axoid) 

 (fig. 47, 2 ) is a thin loose membrane, which is attached by one margin to 

 the neural arch of the atlas, and by the other to the corresponding arch of 

 the axis. Below the superficial part are some deeper and stronger fibres. 

 The posterior primary branch of the second nerve pierces it. 



Fig. 47. 



EXTERNAL LIGAMENTS BEHIND BETWEEN THE ATLAS AND Axis AND THE OCCIPITAL BONE. 

 1. Posterior occipito-atloid ligament. 3. Vertebral artery entering beneath the oc- 



2. Posterior atlo-axoid. 



cipito-atloid ligament. 



The anterior ligament (fig. 46, 3 ) unites the bodies of the first two ver- 

 tebrae in the same manner as the preceding ligament connects their arches. 

 It is thickest in the middle. 



