DISSECTION OF THE HEAD AND NECK. 221 



Synovial Sacs. Each of these belongs to an occipital condyle and 

 its receiving cavity on the front of the atlas. On the inner side each is 

 related to the dura mater and the occipital continuation of the odontoid 

 ligament, and elsewhere they are supported by the occipito-atlantal 

 ligament. 



Movements. — It is at this joint that the nodding movements of the head 

 are executed. 



THE ATLANTO-AXIAL ARTICULATION. 



This joint possesses four ligaments and a synovial capsule. 



The Inferior Atlanto-axial Ligament is riband-shaped, and stretches 

 below the joint, from the forepart of the inferior ridge of the axis to the 

 tubercle of the atlas. 



The Superior Atlanto-axial Ligament is exactly like the inter spinous 

 ligament of the succeeding joints of the neck. It consists of two parallel 

 bands of yellow elastic tissue connecting the bones above the joint. 



The Atlanto-axial Interannular Ligament is membranous, and 

 connects the neural arch of the atlas with that of the axis. It represents 

 the ligamentum subflavum of succeeding joints. 



The Odontoid Ligament is placed at the floor of the spinal canal in 

 this region. To expose it, it is necessary to remove the upper part of 

 the ring of the atlas. It is strong, flattened, and triangular. It is 

 narrow behind, where it is fixed to the depressed upper surface of the 

 odontoid process. It is widest in front, where it is fixed to the floor of 

 the atlas. A thin continuation of the ligament is carried forwards on 

 each side to be attached to the edge of the foramen magnum. 



Synovial Sac. This is supported by the odontoid ligament above, 

 by the inferior atlanto-axial ligament below, and by the interannular 

 ligament laterally. 



Movements. It is at this joint that the movements of the head from 

 side to side are executed. In these movements the axis remains fixed, 

 while the atlas rotates around the odontoid process, carrying with it the 

 head. 



TEMPORO-MAXILLARY ARTICULATION. 



This is the joint formed between the articular surface of the squamous 

 temporal and the condyle of the inferior maxilla. An interarticular 

 fibro-cartilage is interposed between the osseous surfaces, and the joint 

 possesses a capsular ligament and two synovial sacs. 



Capsular Ligament. This envelopes the joint, being attached around 

 the temporal articular surface above, and around the condyle of the 

 lower jaw below. Its inner surface is adherent to the interarticular 

 cartilage. In front and inwardly the capsule is thin and membranous, 

 but behind and on the outer side it shows thickenings which are some- 



