Vertebral Column 



35 



secondary line can be found running across the transverse process for this lamella, 

 dividing the front surface into an inner part for the Psoas and an outer covered by 

 Quadratus lumborum. 



The accessory tubercle or true transverse element gives origin to a slip of Longis- 

 simus dorsi, and the Multifidus spinae lies further in, on the back of the laminae and 

 articular masses, to which it is attached : the mammillary process is on the back 

 margin of the upper articular process, and affords origin to some fibres of Multifidus. 



Examine the line made by the strong ligamenta subflava on the neural surfaces 

 of the laminae. Evidently the ligament does not run into the capsule, as this is turned 



XI. 



XII. 



mu/K/iduf. 



FIG. 29. First lumbar and last two dorsal vertebrae, to show the transverse processes, i, upper 

 (mammillary) ; 2, lower ; and 3, external (accessory) tubercles. The smaller drawing is a 

 scheme of a dissection, including the tenth dorsal vertebra. 



out and away from it : as a result the edge of the ligament is free in the hinder part of 

 the intervertebral foramen just behind the issuing nerve. 



The lower articular processes of the fourth segment are further apart than in 

 those higher up, but not so widely separated as in the last lumbar vertebra, in which 

 they are practically as far apart as the upper pair. There is a slight change in the 

 curvature and direction of the articular surfaces from above downwards, but in all 

 the vertical plane in which they lie, directed mainly in an antero-posterior direction, 

 effectually inhibits the power of rotation in the lumbar column. This is shown in the 

 accompanying scheme (Fig. 28), and compared with the conditions in the cervical 

 and dorsal regions. 



32 



