ARTICULA riONS. LIGAMENTS. 47 1 



The rule is, the articular part of the costal tubercle articulates with the trans- 

 verse process of the lower of the two vertebrae with which the head of the 

 rib articulates ; thus, the first articulates with the first, the second with the 

 second, and the third with the third. 



Are there any exceptions to tlie rule governing tlie articulation of transverse pro- 

 cesses and articular parts of costal tubercles f 



Yes ; the eleventh and twelfth ribs do not articulate with the transverse 

 processes. 



Enumerate tlie articulations of the ribs with the vertebra. 



(i) Costocentral, between heads of ribs and bodies of vertebrae; (2) costo- 

 transverse, between tubercles of ribs and transverse processes. 



COSTOCENTRAL ARTICULATION LIGAMENTS. 



1. Class. Diarthrosis, because of capsule and free movement. 



2. Subdivision. Condylarthrosis, there being absent axial rotation. 



3. Osteological Units. A rib and a vertebra. 



4. Subdivisionai Parts. Head of a rib, centrum, and cartilage. 



Anterior costo-central 

 or stellate ligament 



Costo-central synovial 

 sac 



Laminar portion of inter- 

 vertebral disc 



Central pulpy portion of inter- 

 vertebral disc 



Middle eqsto-trans- 

 verse ligament 



Costo-transverse synovial sao 



Posterior costo-transverse 

 ligament 



FIG. 346. HORIZONTAL SECTION THROUGH THE INTERVKRTEBRAL Disc AND RIBS. 



5. Basis. A capsule lined by synovial membrane. 



6. Subdivisions. Interarticular and costocentral or stellate ligaments. 

 From what point to what point does the interarticular ligament extend / 

 From the interarticular cartilage to the horizontal ridge on the head of the 



rib, between the articular surfaces of the same. 



From wJiat point to wliat point does the stellate ligament extend / 



From the front of the head of a rib, externally, to the bodies and cartilage 

 with which the head articulates. 



Of liow many parts does tlie articulation between the head of the rib and the 

 centrum consist / 



This cavity is divided into two distinct parts by the interarticular ligament. 



COSTOTRANSVERSE ARTICULATION LlGAMENTS. 



Class. Diarthrosis, because of free motion and a capsule. 

 Subdivision. Arthrodia, because motion is simple and gliding. 

 Osteological Units. A rib and a vertebra. 



