TH£ BONES OF THE TRUNK 23 



The transverse processes spring from the junction of the pedicles 

 and laminae, and each is directed outwards and backwards. They 

 are long and club-shaped, being somewhat constricted at their 

 bases, but expanding into knob-like enlargements at their ex- 

 tremities. The anterior surface of the extremity of each presents 

 a circular concave facet, called the costo-tuhercular facet, for articula- 

 tion with the tubercle of a rib. The posterior surface of the 

 extremity gives attachment to the posterior costo - transverse 

 ligament. The anterior svu^face of the transverse process faces 

 the posterior surface of the neck of a rib, and gives attachment to 

 the middle costo- transverse or interosseous ligament. This region 

 corresponds with the costo- transverse foramen in a cervical vertebra. 

 The lower border of the transverse process gives attachment to 

 the superior costo- transverse ligament, which connects it with 

 the crest, or upper border of the neck, of the rib below. The 

 transverse process is serially homologous with a cervical transverse 

 process. 



The neural foramen is almost circular, and is of smaller size than 

 in the cervical or lumbar vertebrae. 



Peculiar Thoracic Vertebrae. — ^These are the first, tenth, eleventh, 

 and twelfth (sometimes also the ninth). 



The Fiftt Thoracic Vertebra. — ^This vertebra closely resembles the 

 seventh cervical, as, indeed, do one or two below it. Its distinctive 

 character is the presence on each side of the body of one entire facet 

 close to the upper part, and situated on the pedicular portion, for the 

 head of the lirst rib, and one demi -facet close to the lower part for 

 a portion of the head of the second rib. With the exception of the 

 inferior articular and transverse processes, this vertebra in other 

 respects closely corresponds with the seventh cervical, with this 

 difference, that the antero-posterior lips of the superior surface of 

 the body of the seventh cervical are replaced by transverse 

 lips lying in front of the superior vertebral notches. The 

 inferior articular and transverse processes are similar to those 

 of a t\-pical thoracic vertebra, each transverse process haWng 

 the usual costo - tubercular facet on the anterior surface of its 

 extremity. 



The Tenth Thoracic Vertebra. — ^This vertebra has usually bne 

 entire facet on either side, mainly on the pedicle, for the head of 

 the tenth rib. This facet, however, may only be a three-quarter 

 tacet, if the ninth thoracic vertebra is normal. It has, usually, a 

 costo- tubercular facet on the anterior aspect of the extremitj' of 

 each transverse process for the tubercle of the tenth rib, but this 

 facet may be wanting. The body and spinous process of this 

 vertebra show indications of the lumbar type, its other characters 

 being thoracic. 



The Eleventh Thoracic Vertebra. — ^This vertebra has an entire 

 facet on the outer surface of each pedicle for the head of the eleventh 

 rib, but there is no facet on the transverse process, which has become 

 short and stunted, the tendency to the club shape being, however. 



