16 ABDOMEN. 



do well to note. M. Meniere* has described to the ribs, the vertebrae, and the pelvis, it 



a case in which a very large vein, arising from becomes evident that they must likewise be 



the external iliac, passed up along the linea destined to act upon the thoracic and pelvic 



alba to the umbilicus, was continued along cavities, as well as upon the vertebral column, 



the obliterated umbilical vein, and opened into In the constitution of the abdominal parietes 



the vena portae. In another case, recorded by we observe, as Berard* remarks, the most 



Manec, the vein originated in the same manner happy adaptation of structure to uses. A 



by two roots, reached the umbilicus, taking completely osseous covering would have greatly 



a course parallel to the umbilical artery, formed interfered with the functions of the abdominal 



an arch outside the navel, and having re-entered organs, which are liable to experience changes 



the abdomen, opened into the vena portae. In both extensive and often very rapid, either by 



another instance which occurred to Cruveilhier reason of the introduction of alimentary matter, 



the superficial veins in the hypogastric region whether solids or fluids, or by the disengage- 



were enormously enlarged, at the umbilicus ment of gases within the digestive tube, or by 



they ended in a trunk as large as a finger, the progressive development of the impregnated 



which communicated with the vena cava as it uterus. We may moreover add that an exact 



passed under the liver.f Berard proposes to repetition of the structure of the walls of the 



explain, by the supposition of the existence thorax would not have been well adapted to 



of such anomalies as those above described, the abdomen for the same reason, namely, the 



the occurrence of fatal hemorrhages from too great resistance which it would afford to 



wounds inflicted at the umbilicus, which have compression from within, thereby interfering 



been attributed to the persistence of the um- with the distensibility of the enclosed viscera, 



bilical vein.J The resistance, too, which a wall so constituted 



c. The lymphatics. Those on the anterior would afford to impulses from without could 

 wall communicate above with the axillary not have been so easily adapted to the impetus 

 glands, and below with those of the groin : the of the forces likely to act upon them as a 

 deep-seated lymphatics of the posterior wall purely muscular wall whose contractions and 

 communicate with the glands which lie along the intensity of them are obedient to the will, 

 the lateral and anterior surfaces of the lumbar The consideration of the action and uses of 

 spine. the abdominal muscles naturally comes under 



d. The nerves. The nerves of the abdo- two heads : 1 . their action upon the abdo- 

 minal parietes are derived from the inferior minal cavity and its contents ; 2. their influ- 

 intercostals and from branches of the lumbar ence on the trunk generally, or parts of it. 

 plexus. The seventh, eighth, ninth, tenth, It is the muscles that enter into the compo- 

 eleventh, and twelfth intercostal nerves termi- sition of the anterior and lateral walls of the 

 nate in supplying the transverse and oblique abdomen which act chiefly on the cavity'and 

 muscles and the recti ; the twelfth lies in front its contained viscera. The solidity of a con- 

 of the quadratus lumborum muscle, and gives siderable portion of the posterior wall, and 

 several filaments to that muscle. The ilio- the great strength of the lumbar muscles, give to 

 scrotal and inguino-cutaneous nerves are the that wall such a power of resistance as enables 

 branches of the lumbar plexus which mainly it to receive the compressed viscera without at 

 supply the inferior part of the oblique and all yielding. A reference simply to the attach- 

 transverse muscles. One branch of the genito- ments of the muscles of the anterior and lateral 

 crural, which is found in the inguinal canal, walls is sufficient to shew that these muscles 

 also sends some twigs to these muscles. when contracted must diminish the capacity 



The posterior wall is supplied by the sub- of the abdomen, both in the lateral and antero- 



divisions of the posterior branches of the posterior directions ; and as the posterior wall 



lumbar nerves. is but little influenced, the viscera will be 



Physiological action of the abdominal parietes pushed partly upwards against the diaphragm, 



and muscles. We have already alluded to the and partly downwards into the cavity of the 



peculiarity which distinguishes the abdominal pelvis, where their further descent is opposed 



cavity when compared with the other great by the levator ani. Hence it appears that 



cavities, namely, that its walls are in greatest a degree of antagonism exists between the 



part composed of contractile tissue. At first diaphragm and the abdominal muscles, as 



view the muscular apparatus of the abdomen well as also between those muscles and the 



would appear to be a great constrictor muscle levator ani. It is extremely difficult to maintain 



destined principally to exert its influence on the abdominal muscles and the diaphragm 



the cavity and its contents ; but when we take at the same moment in a state of contrac- 



into account the attachments of those muscles tion ; in general they alternately yield the 



one to the other : and when it does happen 



* Archives Gen. de Med. t. x. p. 381. The tha ' the y, are simultaneously contracted, the 

 vascular distribution which existed in this subject abdominal viscera must suffer an unusual de- 

 presents, as Meniere has remarked, a striking simi- gree of compression; and it is not improbable 

 larity to that which is naturally found in the Saurian, that vomiting is sometimes produced by Such 

 Ophidian, and Batrachian reptiles, viz. a division a cause and defecation, no doubt, is likewise 

 of the general venous system which communicates ^j- j u rpi A f .-, c 

 with th! hepatic vena portae. aided b / * Th e dan er J the protrusion of 



t Velpeau, Anat. Chir. ed. 2. vol. ii. p. 32, and some of th e hollow viscera between the fibres 

 Manec, Dissertation inaugurale. Paris, 1826. 



J Diet, de Med. art. Abdomen. * Loc. cit. 



