SPECIAL VERTEBRAL ARTICULATIONS. 131 



SPECIAL VERTEBRAL ARTICULATIONS. 



Occipito-atloicl Articulation. — This joint is formed by the 

 •occipital condyles and the glenoid cavities of the atlas, and 

 possesses five ligaments — one capsular, two lateral or styloid, 

 superior suspensory, inferior suspensory. This joint is a true 

 one, having two synovial membranes — one for each condyle. The 

 styloid ligaments pass from the base of the occipital styloid 

 processes to the sides of the atlas. The superior suspensory or 

 occipito-atloid is very broad, and consists of fibres, which cross 

 each other, extending from the superior margin of the foramen 

 magnum to the notch on the anterior border of the atlas. The 

 inferior suspensory or occij>ito-atloid stretches from a notch on 



Fia. 46. 



Neural canal of first three cervical vertebrae, opened from above 

 to show the internal ligaments. The occiput and foramen mag- 

 num ore seen to the right. 6, The odontoid ligament ; a, The 

 occipito-atioid portion (long odontoid) ; c, Superior common 

 ligament ; d, Posterior articular cavity of a vertebral centrum. 



the antero-inferior part of the atlas to the inferior margin of the 

 foramen magnum ; it is thin and membranous. The capsular 

 ligament passing completely round the joint, becomes blended 

 with the other ligaments. The latter are sometimes considered 

 as mere enlargements or strengthenings of the capsular ligament, 

 which, this view being taken, would then become the only liga- 

 ment of the joint. This joint allows of flexion, extension, 

 circumduction, and lateral motion. 



Atlo-axoid Articulation. — This joint is formed by the oppo- 

 sing articular surfaces of the atlas and axis, and is also a true 

 joint. The atlo-axoid ligaments are the capjsular, the superior, 

 the inferior, and the odontoid. The capsular is very broad 

 superiorly, where it closes the atlo-axoid space. The superior 

 ligament passes from the supero-posterior part of the ring 

 of the atlas to the neural spine of the dentata. The inferior 

 joins the inferior spines of the tM'O bones. The odontoid springs 



