118 SURGICAL ANATOMY OF 



disease depends upon caries of the bodies of the vertebrae 

 and abscesses form, the course taken by the pus will de- 

 pend upon the part of the spine which is the seat of dis- 

 ease ; and it generally escapes beneath the pillars of the 

 diaphragm, and passes beneath the fascia, along the side 

 of the aorta and iliac arteries, pointing in the abdominal 

 parietes above Poupart's ligament. If the abscess de- 

 pends upon disease of the lower dorsal vertebrae, the pus 

 is directed forwards by the sheath of the psoas muscle, 

 and points below Poupart's ligament, in the front of the 

 thigh, and external to the vessels. The pus sometimes 

 passes backwards, forming dorsal abscess. If it gets into 

 the subperitoneal areolar tissue in the pelvis, it may find 

 its way into the perineum by the side of the rectum, or 

 pass out of the great sciatic notch, and appear in the 

 region of the great trochanter. From the continuity and 

 density of the fascia of the leg, such collections of matter 

 may make their way into the popliteal space, or even 

 along the side of the tendo-Achillis. 



Injuries to the cord in the dorsal region, if below the 

 second dorsal vertebra, do not affect the upper extremity, 

 but the respiration is greatly affected, owing to implica- 

 tion of the nerves supplying the intercostals and ab- 

 dominal muscles ; moreover, there is paralysis of all the 

 parts supplied by the nerves below the seat of injury. 



Region of the Cavity of the Thorax. 



As this region can scarcely be considered as within 

 the province of surgical anatomy, it is proposed there- 

 fore to allude to it as shortly as possible. Its practical 

 bearings to the surgeon seem rather to be upon the re- 



