LIGAMENTS OF ATLAS AND AXIS. 



169 



Dissection (fig. 49). After the removal of the occipito-axoidean liga- 

 ment, by cutting transversely through it above, and reflecting it, the stu- 

 dent should define a strong band, the transverse ligament which crosses 



Fig. 49. 



INTERNAL LIGAMENTS BETWEEN THE OCCIPITAL BONE AND THE ATLAS AND Axis (Bourgery). 



1. The left cheek ligameut. 3. Cut end of the occipito-axoidean ligament. 



2. The transverse ligament, sending offsets 



upwards and downwards. 



the root of the odontoid process, and sends upwards and downwards a slip 

 to the occipital bone and the axis. The upper offset from the transverse 

 ligament may be cut through afterwards for the purpose of seeing the 

 check ligaments which diverge, one on each side, from the odontoid 

 process. , 



The lateral odontoid or check ligaments (fig. 49, T ) are two strong bun- 

 dles of fibres, attached by one end to the side of the head of the odontoid 

 process, and by the other to a depression on the inner surface of the con- 

 dyle of the occipital bone. These ligaments are covered by the occipito- 

 axoidean band ; their upper fibres are short and almost horizontal, and 

 the lower are longer and oblique. 



Between the lateral bands is a central odontoid ligament, which connects 

 the tip of the odontoid process to the margin of the basilar process of the 

 occipital bone. 



The transverse ligament of the atlas 



Union of the atlas with the axis. 

 (fig. 49, 2 ) is a flat, strong, arched 

 band behind the odontoid process, 

 which is attached on each side to a 

 tubercle below the inner part of the 

 articular process. This ligament is 

 widest in the centre; and at this 

 spot it has a band of longitudinal 

 fibres connected with the upper and 

 lower margins (fig. 49), so as to 

 produce a cruciform appearance : 

 the upper piece is inserted into the 

 basilar process, and the lower into 

 the body of the second vertebra. 

 Its surface towards the cord is con- 

 cealed by the occipito-axoid liga- 

 ment. 



Fig. 50. 



FIRST VERTEBRA WITH THE ODONTOID PROCESS 

 REMOVED FROM THE SOCKET FORMED BT THK 

 BONE AND THE TRANSVERSE LIGAMENT. 



1. Transverse ligament with its offsets cut. 



2. Socket for the odontoid process. 



