1182 THE DIGESTIVE SYSTEM. 



The chief bowel lesion in typhoid fever is found in these aggregated and in the solitary 

 nodules. 



When the surface of one of these nodules from a child's intestine (in which these structures 

 are particularly well developed) is carefully examined, it is seen to be made up, not of a series 

 of separate, rounded nodules grouped together, but rather of a number of wavy, irregular, and 

 branching ridges connected with one another by cross branches (Fig. 981), the whole recalling 

 in miniature the appearance of a raised map of a very mountainous district in which the 

 chief chains run irregular courses, and are joined to one another by connecting ridges. 



Small patches, intermediate in form between solitary and aggregated nodules, and consist- 

 ing of two or three lymph nodules, are also usually present. 



DUODENUM. 



The duodenum, the portion of the digestive tube which immediately succeeds 

 the stomach, is the first part of the small intestine, and differs from the rest of 

 that tube in having no mesentery, and hence it is closely fixed to the posterior 

 abdominal wall. The ducts of the liver and pancreas open into it, and 

 some special glands are found in its wall, known as the duodenal glands of 

 Brunner. 



Shape and Divisions. The duodenum begins at the pylorus, about the level 

 of the first lumbar vertebra, and ends at the left side of the first or second lumbar 

 vertebra (Fig. 932). Between those two points it pursues an irregular course, 

 which has some resemblance to the outline of a horse-shoe. It is made up of 

 three main parts, namely : (1) The pars superior, which begins at the pylorus, 

 passes posteriorly and to the right beneath the liver, and ends at the neck of 

 the gall-bladder by turning down, forming the flexura superior, and joining 

 (2) the pars descendens. This begins at the neck of the gall-bladder, runs down 

 on the posterior abdominal wall, on the right of the vertebral column, behind the 

 transverse colon (Fig. 932), and ends opposite the third or fourth lumbar vertebra. 

 There it turns to the left, and passes into (3) the pars inferior. This portion at 

 first runs more or less transversely to the left, across the vena cava, aorta, and 

 vertebral column (pars horizontalis), and then ascends as far as the inferior surface 

 of the pancreas (pars ascendens). There, at the level of the first or second 

 lumbar vertebra, it bends abruptly forwards, forming the duodeno-jejunal flexure 

 (Fig. 932), and passes into the jejunum. The junction of the pars descendens and 

 pars inferior constitutes the flexura inferior. 



Taking the whole of the duodenum together, it forms an irregular horseshoe- 

 shaped curve, with the opening directed upwards and to the left, and the ends 

 reaching to within about two inches of one another. Within the concavity of 

 the curve the head of the pancreas is placed. 



The incomplete ring which the duodenum makes does not all lie in the same 

 plane ; for, whilst its greater part is placed in a frontal plane, the superior part, 

 and the commencement and termination of the inferior part, lie more in a sagittal 

 plane (Fig. 932). 



Position and Size. As a rule, a little more than half of the duodenum lies 

 in the epigastrium ; the remainder namely, about the inferior third of the descend- 

 ing portion and the adjoining two-thirds of the inferior portion are placed in the 

 umbilical region. With the exception of the terminal ascending portion of the 

 third part, the whole of the duodenum lies to the right of the median plane. 



Its length is usually about 11 inches (27*5 cm.), its first portion being the shortest 

 and its third portion the longest. Its diameter varies considerably, and may be 

 stated to average about 1 J inches when empty, but it may be as much as two 

 inches when distended. 



Relations. Pars Superior. The superior part (O.T. first portion) begins at the 

 pylorus, opposite the first lumbar vertebra. From there it runs to the right, and 

 then posteriorly, beneath the liver, when the stomach is empty, but directly back- 

 wards when it is full; and ends at the neck of the gall-bladder by turning downwards 

 and passing into the descending part. Its length varies from about 1J to 2 inches 

 (3*7 to 5*0 cm.), and is said to be greater when the stomach is empty than when 

 distended. 



