228 DISSECTION OF THE DOG 



Articulatio atlanto-epistrophtca. — The joint cavity of the atlanto- 

 epistrophic articulation, continuous as previously stated with that of the 

 foregoing joint, is enclosed by the customary joint-capsule. Intimately 

 connected therewith, and passing between the arches of the atlas and epistro- 

 pheus, is a tectorial membrane (membrana tectoria) , from which an interspinal 

 ligament (ligamentum interspinal) may be separated with difficulty. Asso- 

 ciated with the dens of the epistropheus are alar and transverse ligaments. 

 The former (ligamenta alaria) spring from the tip of the dens, and diverging 

 proceed forwards to be attached within the occipital condyles. The transverse 

 ligament (lig. transversum dentis), along with the atlas, forms a ring within 

 which the dens rotates. 



Articulationes costo-vertebrales. — Since a rib is in contact by its 

 head with the bodies of two vertebrae, and by its tubercle with the transverse 

 process of the more caudal of the two vertebras, it follows that there are two 

 joints between a typical rib and the vertebral column. 



The capitular articulation (articulatio capituli) possesses two joint-cavities, 

 corresponding to the two vertebral bodies with which the head of the rib is 

 in contact, and separated from each other by an interarticular ligament to 

 which the two joint-capsules are attached. The interarticular ligament (lig. 

 capituli costae interarticulare) springs from the depression on the head of the 

 rib, and passes to the middle plane of the body where it is continuous with the 

 same ligament of the corresponding joint of the other side of the body. Broad 

 at its attachment to the head of the rib, the ligament narrows as it lies under 

 cover of the dorsal longitudinal ligament of the vertebral column. There is 

 a slight connection between the ligament and the intervertebral fibro-cartilage. 

 On the ventral aspect of the joint is the radiate ligament (lig. capituli costae 

 radiatum) with fibres extending, in a radiating fashion, from the neck 

 of the rib to the bodies of the vertebras and the interposed intervertebral 

 fibro-cartilage. 



The costo-transverse articulation (articulatio costo-transversaria) between the 

 tubercle of the rib and the transverse process of the vertebra, is provided with 

 the customary joint-capsule. In addition there are a dorsal ligament and 

 the ligament of the neck. The former (lig. costo-transversaria dorsale) passes 

 from the vertebral transverse process to a point on the rib immediately lateral 

 to the tubercle. The ligament of the neck (lig. colli costae) runs between the 

 vertebra and the dorsal aspect of the neck of the rib. 



Articulatio sacro-iliaca. — The slightly moveable articulation between 

 the sacrum and the ilium is provided with a very short joint-capsule. Ligaments 

 disposed in the vicinity of the joint all tend to restrict its range of movement. 



