TEMPORO-MAXILLARY. 195 



that between the posterior surface of the odontoid process and transverse liga- 

 ment. 



'Actions. The movements permitted in this joint are flexion and extension, 

 which give rise to the ordinary forward or backward nodding of the head, besides 

 slight lateral motion to one or the other side. When either of these actions is 

 carried beyond a slight extent, the whole of the cervical portion of the spine 

 assists in its production. 



2. ARTICULATION OF THE Axis WITH THE OCCIPITAL BONE. 

 Occipito-axoid. Three Odontoid. 



To expose these ligaments, the spinal canal should, be laid open by removing 

 the posterior arch of the atlas, the laminse and spinous process of the axis, and that 

 portion of the occipital bone behind the foramen magnum, as seen in fig. 120. 



The Occipito-axoid Ligament (Apparatus ligamentosus colli) is situated at the 

 upper part of the front surface of the spinal canal. It is a broad and strong 

 ligamentous band, which covers the odontoid process and its ligaments, and appears 

 to be a prolongation upwards of the posterior common ligament of the spine. It 

 is attached, below, to the posterior surface of the body of the axis, and becoming 

 expanded as it ascends, is inserted into the basilar groove of the occipital bone, in 

 front of the foramen magnum. 



Relations. By its anterior surface, it is intimately connected with the transverse 

 ligament ; by its posterior surface with the dura mater. By dividing this ligament 

 transversely across, and turning its ends aside, the transverse and odontoid liga- 

 ments are exposed. 



The Odontoid or Check Ligaments are strong rounded fibrous cords, which 

 arise one on either side of the apex of the odontoid process, and passing obliquely 

 upwards and outwards, are inserted into the rough depressions on the inner side 

 of the condyles of the occipital bone. In the triangular interval left between these 

 ligaments and the margin of the foramen magnum, a third strong ligamentous 

 band (ligamentum suspensorium) may be seen, which passes almost perpendicularly 

 from the apex of the odontoid process to the anterior margin of the foramen, being 

 intimately blended with the anterior occipito-atloid ligament, and upper fasciculus 

 of the transverse ligament of the atlas. 



Actions. The odontoid ligaments serve to limit the extent to which rotation 

 of the cranium may be carried ; hence they have received the name of check 

 ligaments. 



IY. TEMPORO-M AXILLARY ARTICULATION. 



This articulation is a double arthrodia. The parts entering into its formation 

 are, on each side, the anterior part of the glenoid cavity of the temporal bone and 

 the eminentia articularis above; with the condyle of the lower jaw below. The 

 ligaments are the following: 



External Lateral. Stylo-maxillary. 



Internal Lateral. Capsular. 



Interarticular Fibro-cartilage. 



The External Lateral Ligament (fig. 121) is a short, thin, and narrow fasciculus, 

 attached above to the outer surface of the zygoma and to the rough tubercle on 

 its lower border ; below, to the outer surface and posterior border of the neck 

 of the lower jaw. This ligament is broader above than below; its fibres are 

 placed parallel with one another, and directed obliquely downwards and back- 

 wards. Externally, it is covered by the parotid gland and by the integument. 

 Internally, it is in relation with the mterarticular fibro-cartilage and the synovial 

 membranes. 



