The brachiocephalic artery in the dog with special reference to the arterial supply of the esophagus.код для вставкиСкачать
The Brachiocephalic Artery in the Dog with Special Reference to the Arterial Supply of the Esophagus J. F. JARVIS AND ANNETTE M. H. NELL Departments of Anatomy and Surgical Research, University of Cape Town ABSTRACT Two direct branches of the brachiocephalic artery are frequently present in the dog. These are described in 33 dogs and their incidence recorded. One supplies the lower cervical trachea and esophagus and the other the thymus gland and sometimes the pericardium. Suggested names are "Tracheoesophageal" and "Thymopericardial" branches of the brachiocephalic. The embryology of the blood vessels of the esophagus is discussed and the identification of the tracheoesophageal with a secondary anastomotic vessel is considered most likely. Occasional branches from the brachiocephalic artery in man are reviewed. The Arteria Thyroidea Ima seems to bear the closest relationship to this vessel described in the dog. The value of this study in relation to heart-lung preparations and to experimental surgery of the esophagus is suggested. In the course of setting up KnowltonStarling heart-lung preparations in dogs (Sloan & Jarvis, '62) troublesome hemorrhage was often encountered while clearing the brachiocephalic artery preparatory to cannulation. It was subsequently realized that this vessel often has small branches, not mentioned in standard reference books on the anatomy of the dog, which had escaped notice because they were hidden on the posterior aspect of the great vessel; following this a search was made routinely behind the artery and branches found were ligated, after which no more bleeding of this type was encountered. At other times a massive infiltration of the anterior mediastinal tissues with blood occurred after heparinization, and blood was lost from the circuit of the preparation; this bleeding was traced to another small vessel that frequently arose from the base of the main artery on the heart side of the ligature tying in the cannula, so remaining in the circuit. These observations led to the study here reported in which the frequency and distribution of these two branches has been investigated in 33 mongrel dogs. In 12 of these the arterial system had been injected so that the finer ramifications of the vessels could be followed. The branches were searched for by using a binocular loupe with a twofold magnification. The great vessels were then slit open and orifices identified from the intimal aspect under a binocular microscope giving a tenfold magnification. When this was done and a fine probe was inserted into the openings so discovered, a branch was sometimes demonstrated that had previously escaped external examination. The openings of vasa vasorum, also visualized by this method, were always much smaller than those of the smallest external vessels and a probe showed no continuity with external branches. Findings In the dog the aortic arch normally gives rise to but two great vessels, the branchiocephalic and the left subclavian, an arrangement only occasionally found in man. The brachiocephalic divides into the two common carotid arteries and the right subclavian artery, the left common carotid usually being the first to separate; in two of the dogs examined a trifurcation was found, and in two the right subclavian was the first branch with a bicarotid trunk continuing for a short distance. The length of the vessel from its base to the apex of the angle of the h t division was measured in each case, and the variations are set out in figure 1. In nearly every case examined at least one secondary branch from the brachiocephalic was identified, the frequency of such branches being given in table 1. The exact site of origin of these branches varied considerably; figure two depicts one typical and two less common patterns. 1 2 J. F. JARVIS AND ANNETTE M. H. NELL TABLE 1 Branches of brachiocephalic in 33 dogs 1 Thymo-pericardial present Tracheo-esophageal present Given off anteriorly Given off posteriorly 32 SPECIMENS Other origins of trachio-esophageal From right common carotid Left common carotid Right subclavian Left subclavian Multiple sites 19 29 7 22 0 1 1 1 7 which lies almost directly on the left side of the trachea in this region. The caudal branch ran to the tracheal bifurcation giving branches to the esophagus and to the lymph nodes in this area. It was considered that a suitable name for this vessel would be the “Tracheoesophageal branch Fig. 1 Length of brachiocephalic to first major of the brachiocephalic.” branch. On one occasion the caudal division was The commonest arrangement was that seen to follow the vagus nerve to the posa branch emerged from the posterior as- terior aspect of the left lung root, but no pect of the vessel in its distal half and anastomosis of any considerable size ran to the left on the anterior surface of could be observed with the bronchial the trachea. It soon divided into a ce- arteries. In another specimen (fig. 2, no. phalic and a caudal branch, the former 32) it gave a large anastornotic branch being traced headwards for about 6 cm that joined a direct branch from the posand giving off small twigs to the trachea terior aspect of the aortic arch; a third and larger branches to the esophagus variation being a branch that passed to the 0 0 Nolo TYPICAL I lSCALE I 0 I cm Fig. 2 2 No3I , 3 A N T E R I O R TRACHr ESOPH. SHORT BRACWIOCEPH. NO THYMO-PERICARD. ’ BRANCH ARISING A NT E R I 0 R LY BRANCH ARISING POST E R I0R L Y LONG BRACHIOCEPHALIC ANASTOMOSIS B E T W E E N T RACHrESOPH. AND BRANCH OF AORTIC A R C H , Typical and other arrangements of brachiocephalic and its minor branches. BRACHIOCEPHALIC ARTERY IN THE DOG 3 right, anterior to the base of the brachio- the last two arise from the brachiocephalic, cephalic, and supplied the thymus gland. but he gives no details. From this remark In some cases the bifurcation lymph nodes it would appear that the existence of these were supplied by direct branches from the minor branches of the brachiocephalic was recognized over 80 years ago, but since he aortic arch. The tracheoesophageal artery sometimes quotes no earlier authorities it is not clear arose from the anterior aspect of the ves- when this observation was first made. sel, and on a few occasions from either Swenson et al. ('50) state that the blood supthe right or left subclavian or from the ply of the proximal part of the esophagus left common carotid. In several speci- in the dog comes from branches of the thymens the cephalic and caudal parts arose roid artery, direct branches of the subfrom the brachiocephalic as two separate clavian, and bronchoesophageal branches of the aorta arising at the commencement vessels. The other and less constant branch of of its descending part; no mention of the brachiocephalic usually arose from the branches of the brachiocephalic artery is anterior aspect of the vessel near the peri- made. Embryology cardial reflection. Its chief destination was the thymus gland, to which it was A consideration of the early embryonic often the main supply. It frequently gave blood supply of the gut throws but little a small twig to the pericardium. The light on the relation of the tracheoesoname of "Thymopericardial" is therefore phageal artery in the dog to the blood supsuggested for this vessel. On one occa- ply of this region of the esophagus in sion when the thymopericardial was ab- man. Cauldwell et al. ('48) state that the sent the thymus was seen to receive its embryology of this area in mammals has supply from the left internal thoracic, the not been well worked out. Kiebel and right artery giving no branches in this Mall ('12) described ventral segmental vesregion. sels supplying the gut. The highest of It is felt that the findings of this study these is the seventh which subsequently may be of value to any who are working migrates caudad to become the coeliac. on heart-lung preparations or on experi- They consider that the branches from the mental surgery of the great vessels and aorta to the thoracic esophagus do not esophagus in the dog. represent primitive vessels but are later developments. Walmsley ('30) speaks of DISCUSSION splanchnic segmental vessels from which The presence of these branches of the the bronchials are derived, and states that brachiocephalic artery in the dog is not these establish anastomotic links with the mentioned by Bradley ('48) in his book dorsal segmentals which explain the ocon the anatomy of the dog, nor by Sisson casional origin of a bronchial artery from ('53) who bases his description primarily the superior intercostal, subclavian, or on the horse but mentions where other some other vessel in the thorax. Such domestic animals differ. Berry et al. ('31) origins are also described by Hewitt ('30) in a study of the origin of the bronchial and ORahilly et al. ('50). None of these arteries in the dog mention mediastinal authors make any statement about the and tracheoesophageal vessels that give primitive supply to the gut more cranial off the anterior bronchials, but do not de- than this, but it may be presumed that it scribe them as arising from the brachioce- would be by branchial arch arteries. phalic. Swenson et al. ('50) describe the Cairney ('25) quoting other sources states blood supply of the esophagus in the dog that in man the right subclavian artery as coming from the thyroid artery, sometimes gives rise to a small tracheoesobranches of the subclavian, and bronch- phageal branch, and he discusses the posials, with branches direct from the aorta sibility of this vessel being a remnant of contributing to the supply of the mid- the embryonic right aortic arch. Lambert thoracic region. Kuttner (1878) speaks Rodgers ('29) in discussing the arterial of mediastinal, tracheal and tracheoeso- supply to the thyroid gland in man states phageal arteries in the dog; he states that that the superior thyroid is the primitive 4 J. F. JARVIS AND ANNETTE M. H. NELL vessel to the gland and that the inferior supply. In the dog the common carotid is thyroid is a later development, is variable very long, and in one large dog we found in size, and is sometimes absent. It would that it ran 17 cm before giving off its first therefore appear that the tracheoeso- branch, the thyroid. There is therefore a phageal does not represent a primitive much longer gap in the dog than in man vessel, but is likely to be a later develop- between the thyroid and bronchial supply ment formed from anastomotic links that areas, and it is suggested that the tracheoare elaborated later in embryonic life. esophageal branch of the brachiocephalic has been provided to bridge this space. Comparison with man The arteries to the esophagus in man The human brachiocephalic artery does have therefore varied arrangements which occasionally give rise to direct branches, provide several equivalents for the vesthe commonest of which appears to be the sels here described in the dog. The Arteria Thyroidea Ima. Pratt ('16) speaks anastomotic network developed between of this mode of its origin and quotes Beau- splanchnic segmentals, dorsal segmentals, manoir in 1882 as stating that it may send a descending branch to the region of the branchial arch vessels, and later appeartracheal bifurcation and that it may sup- ing channels provides ample opportunity ply the thymus gland. Adachi ('28) de- for variation between different mammals. scribes the inferior thyroid as being some- There seems to be room for an extensive times so small that it does not supply the comparative study of the arterial supply to gland at all, but ends in branches to the the cervical and mediastinal viscera in trachea and esophagus. He states that the mammals. same may be true of the Arteria Thyroidea LITERATURE CITED Ima and confirms its frequent origin from the brachiocephalic. Quain (1878) states Adachi, B. 1928 Die Arteriensystem der Japaner, Band I, 165, Maruzen & Co., Kyoto. that the brachiocephalic may give rise J. L., J. F. Brailsford and I. de Burgh Daley to thymic and bronchial arteries. Cauld- Berry, 1931 The bronchial vascular system in the well et al. ('48) describe the bronchials dog. Proc. Roy. SOC.Lond., 109: 214. as sometimes arising from the brachio- Bradley, 0. C. 1948 Topographical anatomy of the dog, 5th Ed. revised by T. Grahame, Oliver cephalic or from other vessels in the supe& Boyd, London. rior mediastinum, and states that the subJ. 1925 The anomalous right subclavian arteries may supply direct branches Cairney, clavian artery. J. Anat., 59: 278. to the esophagus. Swigart et al. ('50) Cauldwell, E. W., R. G. Siekert, R. E. Lininger describe in detail the usual supply to the 1948 The bronchial arterand B. J. Anson ies. Surg. Gyn. Obstet., 86: 395. cervical esophagus from the inferior thyroid but found that it was absent in 16 Demel, R. 1924 Die gefassversorgang der speisserohe. Arch. f. Klin. Chir., 128: 453. Out of 125 dissections and replaced in Hewitt, R. W. 1930 An abnormal left bronchial most cases by direct or indirect branches artery. J. Anat., 64: 363. of the right subclavian. It is of interest Kiebel, R., and R. P. Mall 1912 Embryology, Vol. 11, 649. J. B. Lippincott & Co., Philathat they only found two cases in which delphia. direct esophageal vessels arose from arvon 1878 Beitrag zur kenntniss die teries in the left side of the neck. Demel Kiittner, kreislaufverhaltnisse der saugethierlunge. Vir('24) in a study of 15 cadavers found in chow's Arch., 73: 494. eight direct branches of the subclavian Lambert, Rodgers 1929 The thyroid arteries considered in relation to their surgical imsupplying the esophagus, anastomosing portance. J. Anat., 64: 50. with the branches of the inferior thyroid O'Rahilly, R., H. Debson and King T. Summerabove and the bronchoesophageal below. field 1950 Subclavian origin of bronchial arIt appears therefore that in man there teries. Anat. Rec., 108: 227. is frequently a special arterial supply to Pratt, G. W. 1916 The thyroidea ima artery. J. Anat. & Phys., SO: 239. the region of the esophagus between the 1878 Quain's anatomy, 8th Ed. Vol. area served by the inferior thyroid and Quain, I, 355, Longmans Green & Co., London. that served by the bronchial arteries. Sloan, A. W., and J. F. Jarvis 1962 Influence When this is absent Demel showed that of venous and arterial pressures on loudness of dog heart sounds. Amer. J. Phys., 202: 649. this part of the esophagus has a poor blood BRACHIOCEPHALIC ARTERY IN THE DOG Swenson, O., K, Merrill, E. C. Pierce and H. F. Rheinlander 1950 Blood and nerve supply to the esophagus. J. Thoracic. Surg., 19: 462. Sissons, S. 1953 The Anatomy of the Domestic Animals, 4th Ed. revised by J. D. Grossman, W. B. Saunders, London. 5 Swigart, la V. L., R. G. Siekert, W. C. Hambley and B. J. Anson 1950 The esophageal arteries. Surg. Gyn. Abstet., 90: 234. Walmsley, T. 1930 A n abnormal left bronchial artery. J. Anat., 64: 363.