THE BACK 



1405 



Muscles. — The student will remember the greater number and complexity and the numerous 

 tendons of the muscles which run up on either side of the spines; the firmness and inextensibility 

 of their sheaths; the large amount of cellular tissue between them; and the fact that toward the 

 nape of the neck these muscles lie exposed instead of being protected in gutters, as is the case 

 below: all these anatomical points explain the extreme painfulness and obstinacy of sprains 

 here. 



Trapezius. — To map out this muscle, the arm should be raised to a right angle with the 

 trunk. The external occipital protuberance should be dotted in, and the superior nuchal line 

 passing out from this; below, the twelfth thoracic spine should be marked; and laterally, the 

 lateral third of the clavicle and the commencement of the scapular spine. Then a line should 

 be drawn from the protuberance vertically downward to the twelfth thoracic spine; a second 

 from about the middle of the superior nuchal hne to the posterior and lateral third of the 

 clavicle; and a third from the last thoracic spine upward and laterally to the root of the spine 

 of the scapula. 



Fig. 1125. — Relations of the Abdominal Viscera to the Anterior Body Wall. 



Sterno-xiphoid line 

 Liver 



Right kidney 

 Right colic (hepatic) 

 flexure 



Ascending colon 



Cscum and vermiform process 



Lateral vertical (mid- 

 clavicular) line 



Sterno-xiphoid line 



Left colic (splenic) 



flexure 

 Stomach 



Addison's "trans- 

 pyloric" Une 



Infracostal line 



Descending colon 

 Transverse colon 



Hiac colon 

 Intertubercular line 



Sigmoid colon 



Latissimus dorsi. — The arm being raised above a right angle, the spines of the sixth thoracic 

 and the third sacral vertebrae should be marked; then the outer hp of the crest of the ihum, the 

 lower two or three ribs, the lower angle of the scapula, and the posterior fold of the axilla, and 

 finally the intertubercular (bicipital) groove should all be marked. 



A vertical line from the sixth thoracic to the third sacral spine will give the spinal origin of 

 the muscle. Another from the third sacral spine to a point on the ihac crest, 2.5 cm. (1 in.) or 

 more lateral to the edge of the sacro-spinalis, will give the origin of the muscle from the sheath 

 of the sacro-spinalis and the ilium. A line from the sixth thoracic spine, ahnost transversely 

 at first, with increasing slight obliquity over the inferior angle of the scapula to the axilla and 

 Intertubercular groove, will mark the upper border of the muscle. Another very oblique line 

 from the point of the iliac crest upward and laterally to the axiUa will give the lower border 

 and the tapering triangular apex of the insertion. The muscle may be attached to the angle 

 of the scapula, or separated from it by a bursa. 



