Rare case of the inferior mesenteric artery arising from the superior mesenteric artery.код для вставкиСкачать
THE ANATOMICAL RECORD 217:99-102 (1987) Rare Case of the Inferior Mesenteric Artery Arising from the Superior Mesenteric Artery SEIICHIRO KITAMURA, TAKAHIKO NISHIGUCHI, AKIRA SAKAI, AND KENZO KUMAMOTO The Second Department of Oral Anatomy, Osaka University Faculty of Dentistry, Osaka, 565 (S.K., TN., A.S.) and The Department ofdnatomy, Meiji College of Oriental Medicine, Kyoto 62903 (K.K.), Japan ABSTRACT The authors observed a variation of the inferior mesenteric artery, which arose from the superior mesenteric artery, in a 69-year-old Japanese male cadaver during dissection in 1984. In this case, no rudiment of the ordinary inferior mesenteric artery could be found on the abdominal aorta. There are few reports of this variation, and an extensive search of the available literature revealed only four cases, including two in Japan. Such a variation had been somewhat inadequately described as an “absence of the inferior mesenteric artery” in the previous reports, but we avoided this terminology, because all of the cases possessed an artery, which, though arising from the superior mesenteric artery instead of the abdominal aorta, had the same branches as a normal inferior mesenteric artery. Consistent with findings observed in the previous cases, the unusual inferior mesenteric artery arose as the first branch of the superior mesenteric artery, with the common trunk of both mesenteric arteries originating from the abdominal aorta at a level at which an ordinary superior mesenteric artery would arise. It is for this reason that we did not adopt another acceptable name, that is, “the common mesenteric artery,” for this variation. The variation can be explained as the result of an unusual development of the embryonic artery system, which comprises a number of ventral splanchnic arteries interconnected by longitudinal anastomotic channels to supply the primitive digestive tube. The inferior mesenteric artery is generally a direct unpaired visceral branch of the abdominal aorta, which diverges at the level of the third lumbar vertebra, considerably below the origin of the superior mesenteric artery. However, a very rare displacement of the inferior mesenteric artery, in which it arose from the superior mesenteric artery, was reported before. Such a variation was previously described, though somewhat inadequately, as an “absence of the inferior mesenteric artery.” The case presented here was observed in a 69-year-old Japanese male cadaver during dissection in 1984. Despite a detailed search, no rudiment of the ordinary inferior mesenteric artery, which normally would arise from the abdominal aorta, could be demonstrated. CASE REPORT (Fig. 1 ) The superior mesenteric artery, having a diameter of about 10 mm, arose singly from the front of the abdominal aorta at the level of the upper margin of the first lumbar vertebra. It descended about 43 mm and then gave off, to our great surprise, the inferior mesenteric artery, with a diameter of about 4.0 mm, to the left and downward, after which it narrowed to a diameter of about 8.0 mm and continued its normal downward course. At about 5 mm from its point of origin, the unusual inferior mesenteric artery gave off the left colic artery 0 1987 ALAN R. LISS, INC. with a diameter of about 2.0 mm. After passing to the left about 48 mm, the left colic artery divided into two branches, each with a diameter of about 2.0 mm: one passing downward t o supply the descending colon and the other continuing laterally. The former ran about 121 mm, while sending its twigs to the descending colon, and finally anastomosed with a branch from the first sigmoid colic artery, which will be described later. The latter passed to the distal half of the transverse colon, with repeated divergences. Unfortunately, we could not examine its anastomosis with the middle colic artery, which was a direct branch of the superior mesenteric artery, because the vessels of this region had already been removed by students at the time of discovery of the variation. The inferior mesenteric artery, after giving off the left colic artery, ran about 91 mm to the left and downward and then divided into the first sigmoid artery passing to the left, laterally and downward, and the superior rectal artery, continuing downward, with diameters of about 4.0 and 3.0 mm, respectively. Three arteries were found to supply the sigmoid colon in this case; we named them the first t o third sigmoid Received April 30, 1986; accepted August 1, 1986. Address reprint requests to Seiichiro Kitamura, The Second Department of Oral Anatomy, Osaka University Faculty of Dentistry. 1-8, Yamadaoka, Suita, Osaka, 565, Japan. 100 S. KITAMURA, T. NISHIGUCHI, A. SAKAI, AND K. KUMAMOTO colic arteries, respectively, as a matter of convenience. The first sigmoid colic artery, after diverging from the inferior mesenteric artery, ran about 13 mm to give off the second sigmoid colic artery with a diameter of about 2.0 mm, which descended in parallel with the superior rectal artery and finally anastomosed with the third sigmoid colic artery arising from the superior rectal artery a t the sigmoid colon region. Subsequently, the first sigmoid colic artery, narrowing to about 2.0 mm in diameter, ran further to the left and then divided into Abbreviations abdominal aorta left colic artery coeliac trunk dorsal aorta left gastric artery hepatic artery lienal artery longitudinal anastomotic channels among the ventral segmental arteries LSA, lateral splanchnic arteries MI and MS, inferior and superior mesenteric arteries PD, primitive digestive tube RS, superior rectal artery SA, somatic arteries SI, SII, and first, second, and third sigmoid colic arteries SIII, VSA, ventral splanchnic arteries A, CL, CT, DA, G, H, L, LA, two branches: one turning upward to reach the descending colon and finally anastomosing with the left colic artery, as described before, and the other descending further to reach the sigmoid colon region. The superior rectal artery, after diverging from the inferior mesenteric artery, further descended to cross in front of the left common iliac artery and enter the pelvic cavity, immediately before which it branched to give off the third sigmoid colic artery with a diameter of about 2.0 mm. The third sigmoid colic artery divided into a branch passing to the upper portion of the rectum and another supplying the lower portion of the sigmoid colon, the latter of which anastomosed with the second sigmoid colic artery described above. DISCUSSION The term “absence of the inferior mesenteric artery,” adopted for this kind of variation in previous reports, would appear to be somewhat inadequate, because all reported cases possessed a n artery that, though arising from the superior mesenteric artery instead of the abdominal aorta, had the same branches as the ordinary inferior mesenteric artery. We, therefore, consider such a variation as “the inferior mesenteric artery arising form the superior mesenteric artery.” But, it may also be considered as a variation characterized by a “common mesenteric trunk,” since the superior and inferior Fig. 1. Photograph showing the branching of the superior mesenteric artery in the case of the subject. An unusual branch (arrow) diverges from the superior mesenteric artery and supplies the inferior mesenteric artery region of usual cases. The ordinary inferior mesenteric artery, originating from the abdominal aorta, is not found anywhere. 101 VARIATION OF THE INFERIOR MESENTERIC ARTERY mesenteric arteries arise as a common trunk from the abdominal aorta. There are few reports on the absence of the inferior mesenteric artery. An extensive search of the available literature through the 19th and 20th centuries has revealed only four reported cases of this variation, including two cases in Japan (Fleishman, 1815-children, age, and sex distinction being unknown, cited from Adachi’s report; Gwyn and Skilton, 1959-79-year-old male; in Japan: Adachi, 1930-45-year-old male; Mori et al., 1960-60-year-old male). In the five cases of the variation including the present one, the common trunk of the superior and inferior mesenteric arteries always arose from the abdominal aorta at a level at which an ordinary superior mesenteric artery would arise. It is for this reason that we did not adopt the name “common mesenteric trunk” for this variation. The inferior mesenteric artery always diverged as the first branch of the superior mesenteric artery within a distance of 1.0 to 4.5 cm from the origin of the latter artery. The artery system for the abdominal alimentary organs is originally segmental in development: it derives from a number of pairs of ventral splanchnic arteries, with segmental character, diverging from the paired dorsal aortae (Williams and Worwick, 1980). The paired ventral splanchnic arteries are distributed to the wall of the yolk sac at an early stage of development, but after fusion of the dorsal aortae they also fuse into unpaired trunks and come to supply the primitive digestive tube (Fig. 2). These trunks are at first connected with each other by longitudinal anastomotic channels, which form dorsal and ventral splanchnic anastomoses along the dorsal and ventral aspects of the tube. In the later stages of development, however, the artery complex along the digestive tube is simplified with the disappearance of a e great number of the vessels, and finally it is transformed into three systems of arteries that supply the foregut, midgut, and hindgut, respectiveIy; the coeliac trunk and the superior and inferior mesenteric arteries. From the above-mentionedontogenesis of the arteries, Tandler (1903, 1904) and Morita (1935) embryonically explained the variations related to the coeliac trunk and superior mesenteric arteries, as follows: The coeliac trunk and the superior mesenteric artery grow out of a net of arteries comprising the proximal four of the ventral splanchnic arteries connected by the longitudinal anastomotic channel (Fig. 3a). In an ordinary process of d C b a Fig. 2. Diagram showing the abdominal segmental somatic and splanchnic arteries of a human embryo about 4 weeks old. f 9 Fig. 3. Diagrams a-d show the patterns of development of the normal coeliac trunk and superior mesenteric artery (b) or their variations (c and d) from the primitive system of the ventral splanchnic arteries (a). This explanation is based on the opinions of Tandler (1903, 1904) and Morita (1935). Those of e-g show the patterns of development of the variation of subject (0 and the intermesenteric arterial communications (g) from the primitive arterial system (e), which are inferred from the patterns of development, a-d. 102 S. KITAMURA, T. NISHIGUCHI, A. SAKAI, AND K. KUMAMOTO development of the arterious net, the middle two of the four splanchnic arteries, together with the longitudinal channel, disappear as shown in Figure 3b to normally form the coeliac trunk and the superior mesenteric artery. On the other hand, such variations as the “truncus coeliacomesentericus” and the “truncus hepatomesentericus” occur owing to unusual patterns of development of the net, which are shown in Figure 3c and d, respectively. There are no reports that embryologically explain the inferior mesenteric artery arising from the superior mesenteric artery. However, we consider it possible to explain this variation by applying the pattern of development of the truncus coeliacomesentericus between the superior and inferior mesenteric arteries. The application seems reasonable, because the ventral splanchnic arteries connected by the longitudinal anastomotic channels continue as far caudally as the hindgut region (Fig. 3e). That is to say, the variation is thought to result from the ontogenetic pattern (Fig. 30 in which the longitudinal channel betewen both mesenteric arteries remains intact and the ventral splanchnic artery originally growing into the ordinary inferior mesenteric artery loses its proximal portion. A similar pattern of development may also explain the other kind of variation between the superior and inferior mesenteric arteries (Williams and Klop, 1957), in which an unusual anastomotic branch, named the intermesenteric arterial communication, was found between both mesenteric arteries (Fig. 3g). LITERATURE CITED Adachi, B. (1930) Das Fehlen der A. mesenterica inferior bei einem Japaner. Anat. Am., 69:431-433. Gwyn, D.G., and J.S. Skilton (1959) A rare variation of the inferior mesenteric artery in man. Anat. Rec., 156:235-238. Mori, Y., I. Ito, S. Hatashita, and K. Yoshikawa (1960) An anomalous case of the mesenteric arteries, absence of A. mesenterica superior. J. Osaka Med,,Coll., 2Ot77-79 (in Japanese). Morita, S. (1935) Uber 3 Falle von seltenen Variationen der A. coeliaca und A. mesenterica superior. Igaku Kenkyu, 9:1993-2006 (in Japanese). Tandler, J. (1903) Zur Entwickelungsgeschichte der menschlichen Darmarterien. Anat. Hefte., 23:187-210. Tandler, J. (1904) Uber die Varietaten der Arteria coeliaca und deren Entwickelung. Anat. Hefte., 25473-500. Williams, G.H., and E.J. Klop (1957) Intermesenteric arterial communications. Univ. Mich. Med. Bull., 23:53-57. Williams, P.L., and R. Worwick (1980) Gray’s Anatomy, 36th ed. Churchill Livingstone, Edinburgh, pp. 149-168.