508 



CAVITY. 



the abdomen may be considered under two 

 heads : 1 . as they regard the parietes of the 

 cavity; and, 2. as they refer to the positions of 

 the contained organs. We shall first examine 

 the abnormal conditions of the parietes. 



Congenital malformations of the abdominal 

 parietes. The first class of these malformations 

 which demands consideration is that which de- 

 pends on a defect in the development of the 

 structures which form the abdominal walls, and 

 these are by far the most numerous. In ex- 

 amining them it is to be borne in mind that 

 many of the abdominal viscera exist before the 

 walls of the cavity, which are formed around 

 the viscera, and that the anterior wall is later in 

 its formation than any of the others. The ca- 

 vity containing the viscera seems at first to be 

 a continuation of that of the umbilical cord, 

 its walls being continued from the sheath of 

 the cord. A distinct separation does not appear 

 to take place until the skin has become deve- 

 loped, when a line of demarcation is evident 

 between the skin of the abdomen and the 

 sheath of the cord. 



The anterior wall may be deficient on 

 both sides to a greater or less extent, the 

 lateral and posterior being also more or less 

 involved. The maximum is when the defect 

 extends not only throughout the whole anterior 

 abdominal wall, but also to that of the thorax, 

 leaving all the viscera of both abdomen and 

 thorax visible, being covered only by a thin 

 membrane ; and frequently congenital deficien- 

 cies of the lower part of the anterior wall of the 

 thorax are accompanied by a more or less ex- 

 tensive defect of the upper part of the same 

 wall of the abdomen, and the heart is included 

 with the abdominal viscera, which are rendered 

 visible, and which, in some instances, protrude 

 forwards. There may, however, be a con- 

 genital deficiency of, or fissure in the deeper 

 seated elements of the anterior abdominal and 

 thoracic wall, and yet the skin remain per- 

 fect and cover the protruded viscera.* But 

 the thoracic parietes may be perfect, and yet 

 there may exist an imperfect condition of the 

 abdominal parietes to a greater or less extent, 

 which imperfection evidently results from the 

 continuance of a greater or less portion of the 

 abdominal wall in that condition in which it 

 naturally exists in the early stages of fetal 

 development. In such cases the viscera are 

 covered by an expansion which is continuous 

 with the sheath of the umbilical cord. When 

 the deficiency of the abdominal wall exists to 

 a great extent, the tumour formed by the pro- 

 truding viscera is designated by the term even- 

 tration ; but if the defect be very limited, and 

 exist, as it generally does, at the base of the 

 umbilical cord, then the protrusion is an exom- 

 phalos or congenital umbilical hernia. Both, 

 as Isidore Geoffrey St. Hilaire remarks, are 

 results of an arrest in the development of the 

 abdominal walls, with this difference, that in 

 the former the cessation of development takes 



* See Geoffrey St. Hilaire's description and plate 

 of an hyperenceohalous foetus : Monstruosites 

 Hnmaines, pp. 183 & seqq. plate 15. 



place at an early period of foetal existence, but 

 in the latter at a late period. In conformity 

 with the same laws, under the influence of 

 which the arrest of development took place, 

 we find that, as in the progress of the natural 

 formation, the small intestine is the last to 

 enter the abdominal cavity, so a larger or 

 smaller portion of that intestine is generally 

 found in the tumour of a congenital exom- 

 phalos. The nature of the contents of an 

 eventration depends evidently on the extent of 

 the deficiency and the region of the abdomen 

 which is most involved. 



In some instances the peritoneum is deficient 

 to an extent corresponding to that of the defi- 

 ciency of the abdominal parietes. This is a 

 rare occurrence, and is generally met with where 

 the defect of development is very extensive.* 

 There are cases, however, where, although the 

 defect was small, the peritoneum was absent 

 to a corresponding extent, and the intestines 

 protruded through the opening in a naked 

 state.f 



The congenital inguinal hernia must likewise 

 be referred to an arrest in the development 

 of a very small portion of the anterior abdo- 

 minal wall. The canal of communication 

 which at one period exists between the peri- 

 toneal sac and the sac of the tunica vaginalis 

 remains pervious, the natural process by which 

 it is closed having been arrested. This mode 

 of explaining the formation of congenital bubo- 

 nocele does not preclude the possibility of its 

 accidental occurrence, the material which closes 

 the canal having given way under the influence 

 of some force applied to it. 



The superior wall of the abdomen sometimes 

 presents a defect of development, giving rise 

 to the congenital perforation of the diaphragm, 

 through which herniae take place into the 

 thorax. Such a perforation may exist on either 

 side, although it is much more frequently 

 found upon the left. (See DIAPHRAGM.) 



The malformation commonly known under 

 the name of ' extroversion of the bladder,' has 

 also connected with it an imperfect state of the 

 anterior abdominal wall interiorly, in conse- 

 quence of the separation of the ossa pubis and 

 of the recti abdominis muscles, and I be- 

 lieve, in general, the absence of the pyrami- 

 dales. (See BLADDER, ABNORMAL ANATOMY.) 

 In these cases the umbilicus is generally situ- 

 ated much lower than usual, and some writers 

 have fallen into the absurd error of supposing 

 that it was absent altogether, in consequence 



* See a case by Ruysch, (observat. Ixxii.) 

 in which the stomach, intestines, and spleen were 

 situated externally to the cavity of the abdomen. 

 Also one by Robinson, in which the defect ex- 

 tended from the abdomen to the umbilicus. Amer. 

 Journal of Med. Sc. Feb. 1833, p. 346; and a very 

 interesting and well-narrated one by my learned 

 friend Dr. Montgomery, in the Trans. Coll. Phys. 

 Dub. vol. i. New Series. See also several other cases 

 referred to in Meckel, Handbuch Der Pathol. 

 Anatomie, Band. i. p. 97 139. 



t See Fried, de ftstu intestinis plane nudis extra 

 abdomen propendentibus nato, in SandifortThesaur. 

 dissert, t. i. Also Howell, in London Med. and 

 Phys. Journal, vol. xlv. 1821. 



