344 



DISSECTION OF THE THORAX. 



Fig. 108. 



bodies of the vertebrae; a second from the neck and tubercle to the trans- 

 verse processes of the vertebrae ; and a third between it and the cartilage. 



Dissection. For the purpose of examining the ligaments between th<> 

 rib and the vertebrae, take a piece of the spinal column with three or four 

 ribs attached. After removing the intercostal and other muscles, and the 

 loose tissue from the surface of the bones, the student will be able to define, 

 as below, the ligaments passing from the head and neck of the rib to the 

 bodies and transverse processes of the vertebrie. 



The ligaments attaching the costal cartilage to the rib and sternum arc, 

 to be dissected on the part of the thorax which was removed in opening 

 the cavity. 



LIGAMENTS OF THE HEAD OF THE RIB. Where the head of the rib is 



received into a hollow in the bodies of two 

 continuous vertebrae, the articulation is pro- 

 vided with two retaining ligaments costo- 

 vertebral and interarticular, with two syno- 

 vial sacs. 



The costo-vertebral ligament (fig. 108, 3 ), 

 named stellate from its form, is composed of 

 radiating fibres, and is placed in front of the 

 joint. Attached by one end to the rib, it is 

 divided at the other into three sets of fibres: 

 The upper, the largest, ascends to the body 

 of the vertebra above the rib head ; the 

 lower descends to the vertebra below the 

 head; and the central part is united with the 

 fibro-cartilage between the vertebrae. 



Where the rib is in contact with only one 

 vertebra, as in the first, eleventh, and twelfth, 

 the ligament has but two sets of fibres. The 

 chief fibres in those three joints are fixed 

 into the body of that vertebra which is 

 touched by the costal head ; whilst the as- 

 cend'ng band is attached to the body of the 

 vertebra immediately above. In the first 

 rib-jo'nt the ascending band is continued to 

 the last cervical vertebra. 



The interarticular ligament will be seen 

 when the stellate is divided. It is a short 

 thin band of fibro-cartilage, which is attached 

 on one side to the ridge separating the articu- 

 lar surfaces on the head of the rib, and on 

 the other to the fibro-cartilage between the 

 vertebrae. In the joints of the first, eleventh, 



and twelfth ribs, where the head is not in contact with the intervertebnil 

 substance, the ligament is absent. 



Synovial sacs. There are two sacs in the articulation, one on each 

 side of the interarticular ligament. In the three joints before mentioned 

 (1st, llth, and 12th) there is but one sac. 



Movements. In the costo-vertebral articulation there is a gliding of the 

 rib up and down, and forwards and backwards. The movement of the 

 head is more limited in the first seven ribs which are fixed to the sternum 

 than in the others; and is greatest in the last two, in consequence of the 



LlQAMBNTS OF THE RlBS AND VER- 

 TEBRAE (Bourgery). 



1 . Anterior ligament of the bodies of 



the vertebra. 



2. Lateral part of the anterior liga- 



ment of the spine. 



3. Ligament (stellate) between the 



vertebrae and head of the rib. 



4. Ascending costo-transverse liga- 



ment. 



5. Interspinous ligament. 



