PANCREAS. 



83 



creas has been described by anatomists as 

 possessing a body and two extremities ; and of 

 these extremities one, which is enlarged and 

 clubbed, has been called the head; the other, 

 tapering and acuminated, has been called the 

 tail; the middle portion, the great mass of 

 the gland, being the body : other describers* 

 have suppressed the body altogether, and de- 

 scribed as the tail all that portion which is 

 not included in the curved intumescence at 

 the right extremity, which they designate the 

 head. Indeed the imaginations of anatomists 

 have been largely drawn on to supply analogies 

 whereby to illustrate the shape of this organ. 

 Some have compared it to a hammer, some 

 to a dog's tongue; among them all I think the 

 best is that which compares it to a pistol. 



But, passing by these fanciful resemblances, 

 the pancreas, from its transverse elongation 

 and antero-posterior flattening, presents for 

 description a right and left extremity, an 

 upper and lower border, and an anterior and 

 posterior surface ; and these parts 1 shall de- 

 scribe in succession in the order in which I 

 have mentioned them. 



The right extremity, to which the name 

 head has been assigned, is that portion which 

 is engaged in the duodenal curvature, and to 

 which, from its occasional separation from the 

 rest of the gland, the name of lesser pancreas 

 has also been givenf : it differs from the rest 

 of the gland in being thicker and more mas- 

 sive, curved instead of straight, and situated 

 on a more posterior plane. It is thus formed : 

 when the pancreas, in passing from left to 

 right, has arrived at the duodenum, it be- 

 comes closely attached to that viscus, and 

 follows its course, first downwards, and then 

 to the left, passing by its extremity, behind 

 the superior mesenteric vessels, for which it 

 thus forms a sort of groove or channel. It is 

 by the fusion and massing of this curvature 

 that the head is formed ; but in very young 

 subjects, and in the lower animals, the curva- 

 ture of the pancreas is as conspicuous as that of 

 the duodenum, and by separating it from its 

 attachments, and straightening it out, all ap- 

 pearance of head vanishes, and it becomes a 

 long prism, or flattened cylinder of even thick- 

 ness throughout. 



In the human adult, however, it is impos- 

 sible thus to unravel and straighten the right 

 extremity ; and the fusion of the parts has 

 often proceeded to such an extent as entirely 

 to obliterate the original curvature, the groove 

 for the vena portae and superior mesenteric 

 vessels being the only trace of its concavity. 



The left extremity gradually tapers, getting 

 both narrower and thinner ; it is sometimes 

 bifurcated, sometimes blunted and flattened 

 against the spleen, and sometimes slightly 

 enlarged ; it presents nothing for special de- 

 scription. 



The upper border is much thicker than the 

 lower, so much so, that some anatomists 

 have described the gland as being prismatic. 



* Meckel, Manuel d'Anatomie. 



f Some anatomists, as Professor Ellis, make the 

 head synonymous with the lesser pancreas, inde- 

 pendently of this separation. 



In the middle the coeliac axis rests upon it ; to 

 the right the hepatic artery and first portion 

 of the duodenum are in contact with it, and 

 to the left it is deeply grooved by the splenic 

 artery. 



This groove does not run along the top of 

 the border, parallel to it, but crosses it ob- 

 liquely from behind forwards as it passes to 

 the left extremity, curving over it, as it were, 

 so that while the commencement of the ar- 

 tery is behind the pancreas, its terminal 

 branches are in front (see fig. 54.). Some- 

 times this groove is converted into a canal, by 

 the gland closing over it. 



The lower border, much thinner, is tilted 

 rather forwards to the right, by the passage of 

 the superior mesenteric vessels beneath it, 

 which separate it from the third portion of 

 the duodenum ; on the left the inferior me- 

 senteric vein passes beneath it to join the 

 splenic. 



The anterior surface looks upwards as well 

 as forwards, and is convex both transversely 

 and longitudinally ; it is the only portion of 

 the gland that is covered by peritoneum : 

 from this circumstance, as well as from its 

 being the free surface, it is very smooth. 



The posterior surface contrasts strongly with 

 the anterior, for being uncovered by peri- 

 toneum, and closely applied to all those struc- 

 tures against which it lies, it presents many 

 irregular elevations and depressions, corre- 

 sponding with the uneven surface which these 

 structures contribute to form. 



Size and weight. The size and weight of 

 the pancreas are liable to great variety, and 

 hence different authors have stated them very 

 variously. Wharton* gives its weight as five 

 ounces ; Meckel, from four to six ; Cruveilhier 

 states its limit as six ounces, but thinks 

 that a healthy pancreas may be as small as 

 two ounces and a half; Soemmerring also 

 considers six ounces a maximum, but carries 

 his minimum as low as an ounce and a 

 half. According to Krause and Glendinniug, 

 its usual weight is from two and a quarter to 

 three and a half ounces. Its size is stated by 

 Meckel as six inches long and one thick ; 

 Ellis gives its length as seven inches ; Quain 

 and Sharpey, from six to eight inches, with 

 an average breadth of an inch and a half ; 

 according to Wharton, its length is about 

 five inches, its greatest breadth one and a 

 half, and its thickness one inch. Of all these 

 weights and measurements I think that of 

 Wharton, which is the earliest, comes nearest 

 the truth; only his measurement of length is 

 too little. From a large number of obser- 

 vations I find the average weight to be from 

 four to five ounces, the length seven inches, 

 the greatest breadth an inch and a half, 

 and the thickness three quarters of an inch. 

 It is smaller in women than men, but only 

 in proportion to the difference of size. 

 Scemmerring says-)- that it is proportionately 

 larger in the foetus and the new-born infant 



* Adenographia, p. 72. 



f " In nondum nato homine et brevi adeo post 

 parttim, majus pro corporis mole videtur quaiu in 

 adulto." Corp. Hum. Fab. 



