ARTICULATIONS OF THE THORACIC LIMB 245 



either side of the foramen magnum. The transverse ligament of the atlas (Lig 

 transversum atlantis) stretches across the dorsal surface of the dens and binds it 

 down on the ventral arch of the atlas, a bursa being interposed. It is attached on 

 either side to the lateral mass of the atlas. 



The tAvo capsules of the atlanto-occipital joint communicate with each other 

 and usually with the capsule of the atlanto-axial joint also. 



Articulations of the Thorax 



^ Ox.— The second to the eleventh costo-chondral joints inclusive are diarthroses 

 with close capsules, reinforced externally. (They are synchondroses in the sheep.) 

 The upper parts of the cartilages are attached to each other by distinct elastic liga- 

 ments (Ligg. intercostaha). 



The first pair of chondro-sternal joints are separate from each other; inter- 

 crossing fibers unite the costo-chondral junctions above the joints. 



The first segment of the sternum forms with the body a diarthrodial interstemal 

 joint (Articulatio intersternalis). The anterior joint surface is concave, the pos- 

 terior convex. The joint is surrounded by a close capsule, and the joint surfaces 

 are attached to each by a small inter-articular ligament. Limited lateral move- 

 ment is possible. (In the sheep the joint is a synchondrosis.) Both surfaces of the 

 sternum are covered by a layer of fibrous tissue (Membrana sterni). 



pig- — The second to the fifth or sixth costo-chondral joints are diarthroses. 

 The intersternal articulation and the sternal ligaments resemble those of the ox. 



Dog. — The first chondro-sternal joints do not coalesce. The internal sternal 

 ligament divides into three bands. 



TEMPORO-MANDIBULAR ARTICULATION 



Ox. — The articular surfaces are of such a character as to permit more extensive 

 transverse movement than in the horse {vide Osteology). The posterior ligament 

 is absent. 



Pig. — The considerable longitudinal diameter of the temporal articular sur- 

 faces and the very small size of the postglenoid process allow great freedom of 

 protraction and retraction of the lower jaw. Transverse movement is limited. 

 The posterior ligament is aljsent. 



Dog. — The articular surfaces allow extremely little transverse or gliding move- 

 ment. They are cylindrical in curvature, and the interarticular disc is very thin. 

 The posterior ligament is absent. 



The other articulations of the skull are sufficiently described in the Osteology. 



ARTICULATIONS OF THE THORACIC LiMB 

 SHOULDER JOINT 



Ox. — The articular angle is about 100°. 



Pig and Dog. — The joint capsule communicates so freely with the bicipital 

 bursa that the latter may well be regarded as a pouch of the capsule. There is a 

 rudimentary marginal cartilage around the rim of the glenoid cavity. In the pig 

 the front of the capsule is reinforced by cruciate bands. In the dog there is usu- 

 ally a strong band extending from the acromion to the lateral part of the capsule; 

 another band (Ligamentum coraco-acromiale) often stretches between the scapular 

 tuberosity and the acromion. 



