PRACTICAL CONSIDERATIONS: THE ABDOMEN. 



535 



The distribution to the pelvic organs will be considered later, but it may be said 

 here that the pelvic viscera are supplied from the fifth lumbar to the fourth sacral 

 segment and that no visceral 



branches emerge from the Fig. 535. 



second, third, or fourth lum- 

 bar segments. 



Division of any of the 

 motor nerves interferes with 

 the function and ultimately 

 with the nutrition of that 

 portion of the musculature 

 of the abdominal wall that is 

 supplied by them, giving rise 

 to weakness over that area, 

 favoring the development of 

 ventral hernia, and, if ex- 

 tensive, interfering with the 

 physiological action of those 

 muscles in defecation, urina- 

 tion, or parturition. 



For clinical purposes 

 these nerves may be divided 

 into three groups (Eads): 

 (a) the seventh and eighth 

 intercostals ascend obliquely 

 and supply the upper third 

 of the abdominal wall ; {b) 

 the ninth and tenth intercos- 

 tals run horizontally inward 

 and supply the middle third ; 

 (r) the eleventh intercostal, 

 the last thoracic, and the ilio- 

 hypogastric and ilio-inguinal 

 nerves run obliquely down- 

 ward and inward and supply 

 the lower third. 



It is obvious that verti- 

 cal incisions elsewhere than 

 in the linea alba (the nerves 

 do not cross the mid-line) 

 will divide a larger number 

 of these nerves and result 

 in more extensive atrophy of 

 abdominal wall than will in- 

 cisions more nearly parallel 

 with the nerves and, when 

 possible, with the chief mus- 

 cular fibres of the region in- 

 volved. 



The Anatomy of Ab- 

 domiiial bicisions. — A dia- 

 grammatic representation of 

 the structures of the abdom- 

 inal wall in their relation to 

 the most important incisions 

 may help to elucidate the 



practical application of some of the above-mentioned facts. It should be noted that 

 in many of these incisions the approximately parallel fibres of the internal oblique 

 and transversalis (where they are both muscular) may be regarded as one layer and 



Diagram of distribution of cutaneous ner\'es, based on figures of Hasse 

 and of Cunningham. On right side, areas supplied by indicated nerves are 

 shown ; on left side, points at which nerves pierce the deep fascia. V^. 

 V'^, V^, divisions of fifth crania! nerve; GA, great auricular; GO, SO. 

 greater and smaller occipital ; SC, superficial cervical ; S/, CI, Ac, sternal, 

 clavicular, and acromial branches of supraclavicular (Scl) ; O, circumflex ; 

 MS, musculo-spiral ; IH, intercosto-humeral ; LIC, IC, lesser internal and 

 internal cutaneous ; EC, external cutaneous ; IH, ilio-hypogastric ; //, ilio- 

 inguinal ; 7"'2 last thoracic; GC, genito-crural ; i?C, external cutaneous; 

 MC, middle cutaneous ; IC, internal cutaneous ; P, pudic ; .S'^', small sciatic ; 

 O, obturator; C, T,L, and S, cervical, thoracic, lumbar, and spinal nerves. 



