DISSECTION OF THE BACK 49 



of the vertebrae (Fig. 25). They follow each other in con- 

 secutive order, and it may be noted, when the finger is passed 

 over them, that all of them do not lie in the median plane ; 

 some may be deflected, in a slight degree, to one side or the 

 other. The spines of the vertebras are the only parts of 

 the spinal column which come to the surface ; they alone 

 yield direct information, by touch, to the surgeon as to the 

 condition of the spine. At the lower end of the neck, the 

 spine of the seventh cervical vertebra (vertebra prominent) 

 makes a visible projection ; and the spines of the first 

 two thoracic vertebrae likewise are very prominent. As 

 a rule, the most evident of the three is that of the first 

 thoracic vertebra. At a lower level, in subjects of good 

 muscular development, a median furrow is produced by the 

 prominence of the sacrospinalis muscle on each side, and 

 the spines of the vertebrae may be felt at the bottom of 

 the groove. The furrow attains its greatest depth in the 

 upper part of the lumbar region, and it fades away, below, 

 at the level of the spine of the third sacral vertebra. The 

 finger should next be passed downwards from the third sacral 

 spine, between the buttocks, along the lower part of the tuber- 

 culated posterior surface of the sacrum, and along the posterior 

 surface of the coccyx to the tip of the coccyx, which is the 

 inferior extremity of the vertebral column. Afterwards the 

 finger should be carried along the crest of the ilium. It 

 commences at the posterior superior spine of the ilium which 

 can easily be detected because its position is indicated by 

 a small but distinct dimple which lies at the level of the 

 second sacral spine. From the posterior superior spine the 

 crest of the ilium pursues a sigmoid course, laterally and 

 forwards. The highest point it reaches is on a level with 

 the spine of the fourth lumbar vertebra, and it terminates 

 in front in a prominence called the anterior superior 

 spine. 



The scapula, or shoulder blade, is, for the most part, thickly 

 covered by muscles ; but, in spite of that, its general outline 

 can be made out (Fig. 25). It covers a considerable area of 

 the upper portion of the posterior aspect of the thorax. With 

 the hand by the side its medial angle lies over the second 

 rib, the root of its spine is placed opposite the spine of the 

 third thoracic vertebra, whilst its inferior angle reaches 

 down as far as the seventh, or even the eighth, rib. The 



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