262 ANATOMY IN A NUTSHELL. 



to the ligamenta subflava which are below the axis but has no elastic tissue in 

 its composition. In front this ligament is attached to the dura mater and be- 

 hind are the Rectus capitis posticus minor and Superior oblique muscles. 



The two capsular ligaments are attached above to the margins of the con- 

 dyL - of the occipital bone and below to the margins of the articular surfaces of 

 the atlas. Each capsular ligament is lined with synovial membrane which 

 sometimes communicates with the synovial membrane of the transverse odon- 

 toid ligament. 



The two anterior oblique or lateral occipito-atlantal ligaments are situated 

 in front of the external part of the capsular ligament. They are attached above 

 to the jugular process of the occipital bone, and below to the base of the trans- 

 verse process of the atlas. Their direction is forward, upward, and inward. 



The articulation of the lower part of the atlas with the upper part of the 

 axis is a diarthrodiaJ joint, subclass arthrodial. The nerve supply is the loop 

 between the first and second cervical nerves. The blood supply is the vertebral 

 artery. The ligaments are anterior atlanto-axial, posterior atlanto-axial, 

 transverse, and two capsular. 



The anterior atlanto-axial ligament is attached above to the anterior sur- 

 face and lower border of the anterior arch of the atlas, and below to the base 

 of the odontoid process and the transverse ridge on the front of the body of the 

 axis. It is continuous on each side with the capsular ligaments. In front in 

 the median line is the anterior common ligament of the vertebral column which 

 is sometimes called the superficial anterior atlanto-axial ligament. It has im- 

 mediately in front the Longus colli, then the Recti capitis antici minores. 



The posterior atlanto-axial ligament takes the place of the ligamenta sub- 

 flava of the joints below the axis. It is attached above to the posterior surface 

 and lower edge of the posterior arch of the atlas and below to the dorsal aspect 

 of the upper edge of the lamina of the axis. It is continuous with the capsular 

 Ligament on each side. It is perforated on each side by the second cervical 

 nerve. In front it is connected to the dura mater, behind is the Inferior ob- 

 lique muscle. 



The two capsular ligaments. These articulations are between the superior 

 articular surfaces of the axis and inferior articular surface of the atlas. Each 

 joint has a loose capsular ligament and synovial sac. These ligaments are 

 strengthened in front and behind by the anterior and posterior atlanto-axial 

 ligaments. 



The transverse ligament is a strong fibrous band passing from the tubercles 

 on the inner side of the lateral masses of the atlas, holding the odontoid process 

 in place. It is thicker in the center and gives fibers which pass above to the 

 basilar process of the occipital and some passing below to the base of the odon- 

 toid process and body of the axis, thus forming a crucial ligament. This liga- 

 ment divides the canal of the atlas into two parts, a small anterior one which 

 is for the odontoid process and a large posterior one for the spinal cord, the spinal 

 acci ssory nerves, the spinal arteries, vertebral arteries, and the meninges of the 

 cord. 



The articulation of the posterior surface of the anterior arch of the atlas 



