16 



ABDOMEN. 



do well to note. M. Meniere* has described 

 a case in which a very large vein, arising from 

 the external iliac, passed up along the linea 

 alba to the umbilicus, was continued along 

 the obliterated umbilical vein, and opened into 

 the vena portoe. In another case, recorded by 

 Manec, the vein originated iu the same manner 

 by two roots, reached the umbilicus, taking 

 a course parallel to the umbilical artery, formed 

 an arch outside the navel, and having re-entered 

 the abdomen, opened into the vena portae. In 

 another instance which occurred to Cruveilhier 

 the superficial veins in the hypogastric region 

 were enormously enlarged, at the umbilicus 

 they ended in a trunk as large as a finger, 

 which communicated with the vena cava as it 

 passed under the liver.f Berard proposes to 

 explain, by the supposition of the existence 

 of such anomalies as those above described, 

 the occurrence of fatal hemorrhages from 

 wounds inflicted at the umbilicus, which have 

 been attributed to the persistence of the um- 

 bilical vein.J 



c. The lymphatics. Those on the anterior 

 wall communicate above with the axillary 

 glands, and below with those of the groin : the 

 deep-seated lymphatics of the posterior wall 

 communicate with the glands which lie along 

 the lateral and anterior surfaces of the lumbar 

 spine. 



d. The nerves. The nerves of the abdo- 

 minal parietes are derived from the inferior 

 intercostals and from branches of the lumbar 

 plexus. The seventh, eighth, ninth, tenth, 

 eleventh, and twelfth intercostal nerves termi- 

 nate in supplying the transverse and oblique 

 muscles and the recti ; the twelfth lies in front 

 of the quadratus lumborum muscle, and gives 

 several filaments to that muscle. The ilio- 

 scrotal and inguino-cutaneous nerves are the 

 branches of the lumbar plexus which mainly 

 supply the inferior part of the oblique and 

 transverse muscles. One branch of thegenito- 

 crural, which is found in the inguinal canal, 

 also sends some twigs to these muscles. 



The posterior wall is supplied by the sub- 

 divisions of the posterior branches of the 

 lumbar nerves. 



Physiological action of the abdominal parietes 

 and muscles. We have already alluded to the 

 peculiarity which distinguishes the abdominal 

 cavity when compared with the other great 

 cavities, namely, that its walls are in greatest 

 part composed of contractile tissue. At first 

 view the muscular apparatus of the abdomen 

 would appear to be a great constrictor muscle 

 destined principally to exert its influence on 

 the cavity and its contents ; but when we take 

 into account the attachments of those muscles 



* Archives Gen. de Med. t. x. p. 381. The 

 vascular distribution which existed in this subject 

 presents, as Meniere has remarked, a striking simi- 

 larity to that which is naturally found in the Saurian, 

 Ophidian, and Batrachian reptiles, viz. a division 

 of the general venous system which communicates 

 with the hepatic vena portse. 



t Velpeau, Anat. Chir. ed. 2. vol. ii. p. 32, and 

 Manec, Dissertation inaugurale. Paris, 1826. 



t Diet, de Med. art. Abdomen. 



to the ribs, the vertebrae, and the pelvis, it 

 becomes evident that they must likewise be 

 destined to act upon the thoracic and pelvic 

 cavities, as well as upon the vertebral column. 

 In the constitution of the abdominal parietes 

 we observe, as Berard* remarks, the most 

 happy adaptation of structure to uses. A 

 completely osseous covering would have greatly 

 interfered with the functions of the abdominal 

 organs, which are liable to experience changes 

 both extensive and often very rapid, either by 

 reason of the introduction of alimentary matter, 

 whether solids or fluids, or by the disengage- 

 ment of gases within the digestive tube, or by 

 the progressive development of the impregnated 

 uterus. We may moreover add that an exact 

 repetition of the structure of the walls of the 

 thorax would not have been well adapted to 

 the abdomen for the same reason, namely, the 

 too great resistance which it would afford to 

 compression from within, thereby interfering 

 with the distensibility of the enclosed viscera. 

 The resistance, too, which a wall so constituted 

 would afford to impulses from without could 

 not have been so easily adapted to the impetus 

 of the forces likely to act upon them as a 

 purely muscular wall whose contractions and 

 the intensity of them are obedient to the will. 



The consideration of the action and uses of 

 the abdominal muscles naturally comes under 

 two heads : 1 . their action upon the abdo- 

 minal cavity and its contents ; 2. their influ- 

 ence on the trunk generally, or parts of it. 



It is the muscles that enter into the compo- 

 sition of the anterior and lateral walls of the 

 abdomen which act chiefly on the cavity and 

 its contained viscera. The solidity of a con- 

 siderable portion of the posterior wall, and 

 the great strength of the lumbar muscles, give to 

 that wall such a power of resistance as enables 

 it to receive the compressed viscera without at 

 all yielding. A reference simply to the attach- 

 ments of the muscles of the anterior and lateral 

 walls is sufficient to shew that these muscles 

 when contracted must diminish the capacity 

 of the abdomen, both in the lateral and antero- 

 posterior directions ; and as the posterior wall 

 is but little influenced, the viscera will be 

 pushed partly upwards against the diaphragm, 

 and partly downwards into the cavity of the 

 pelvis, where their further descent is opposed 

 by the levator ani. Hence it appears that 

 a degree of antagonism exists between the 

 diaphragm and the abdominal muscles, as 

 well as also between those muscles and the 

 levator ani. It is extremely difficult to maintain 

 the abdominal muscles and the diaphragm 

 at the same moment in a state of contrac- 

 tion ; in general they alternately yield the 

 one to the other : and when it does happen 

 that they are simultaneously contracted, the 

 abdominal viscera must suffer an unusual de- 

 gree of compression ; and it is not improbable 

 that vomiting is sometimes produced by such 

 a cause, and defecation, no doubt, is likewise 

 aided by it. The danger of the protrusion of 

 some of the hollow viscera between the fibres 



* Loc. cit. 



