An Anomalous Case of A. Subclavia Dextra Rising from Arcus Aortae as the Last Branch. Hiroshi Hanai, Atsuko Ryumon, Kenji Kamakura

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1 An Anomalous Case of A. Subclavia Dextra Rising from Arcus Aortae as the Last Branch By Hiroshi Hanai, Atsuko Ryumon, Kenji Kamakura and Seiji Kaneko Department of Anatomy, Osaka Dental College, Osaka (Director: Prof. Y. Taniguchi) Argument of this report was announced at the 31st Kinkidistrict meeting of the Japanese Association of Anatomists, 1962, Osaka. Since Suzuki (1894) has reported an anomalous case of the right subclavian artery rising from Arcus aortae as the last branch, twenty-one similar cases have been reported in Japan, that on fetus was only one. Now, one more case is added in a nine-month-old fetus. This case was found when the anterior wall of the thorax and Arcus aortae were removed to inject the colloidal resin into the common carotid arteries for making a corrosion specimen. Therefore, the branching part of the right common carotid from the arch has regrettably been removed. This case is found out of two hundred fetuses observed. The branches of Arcus aortae are as follows in order : 1) The right common carotid artery (c. 2 mm in diameter) takes a normal course, however the authors can not make a detailed observation, being removed its branching portion from the arcus. 2) The left common carotid artery (c. 2 mm in diameter) rises singly from the superior wall of the arch. 3) The left subclavian artery (c. 2.7 mm in diameter) rises closely next to the left common carotid from the superior wall of the arcus and takes a normal course. About 5 mm distal to the origin, the artery sends from the superior wall off the left vertebral artery, which enters the transverse foramen of the sixth vertebra. And, further 2 mm distal to the origin of the vertebral, the subclavian sends from the superior wall off the thyreocervical trunk, which soon trifurcates into the inferior thyreoid, the ascending cervical 31

2 32 H. Hanai, A. Rytimon, K. Kamakura & S. Kaneko and the transverse cervical arteries, and from the anterior wall off the internal thoracic. 4) The right subclavian artery (c. 2.7 mm in diameter) originates upward and to the right from the posteromedial wall of the aorta, about 5 mm distal to the origin of the left subclavian just before the aortic arch continues to the thoracic aorta, in contact with the anterolateral surface of the body of the thoracic vertebra at the level between the second and third thoracic vertebrae. The artery runs at first straight upward and to the right between the esophagus and the first thoracic vertebra, and changes its direction laterally about in front of the right first Articulatio capitis costae and at last continues to the axillary artery which takes a normal course. At about 13.5 mm distal to the origin of the right subclavian, the right vertebral artery leaves from the superior wall and enters the transverse foramen of the sixth vertebra. Further about 3.5 mm distal to the origin of the vertebra, the subclavian sends from the superior wall off the thyreocervical trunk, which gives off the inferior thyreoid, the ascending cervical and the transverse cervical, and the internal thoracic from the anterior wall. In the descending part of the aortic arch just inferior to the origin of the right subclavian, the arterial duct (c. 2 mm in diameter) joins the arch. The left vagus nerve comes to the lateral to the arch to branch off the left recurrent nerve, and further runs downward. The recurrent nerve comes to the posteromedial to the descending part of the arch, rounding posteriorly beneath the arterial duct, and ascends in the lateral to the esophagus. The right vagus nerve descends along the right bronchus in its posterolateral, crossing the right subclavian in its front. The right recurrent nerve is lacking, for the vagus nerve sends directly off the laryngeal nerve and rami to the superior part of the trachea and esophagus successively before it crosses the subclavian. The sympathetic nerves on both sides lie normally in the posterior to the subclavian arteries on both sides, respectively. In Japan, the case in this paper is ranked as the twenty-second generally, as the second in fetuses. The authors conclude and compare the twenty-two cases in the following tables : (Fig. between brackets in all following tables indicate the case in this report.)

3 Anomalous Origin of A. subclavia dextra in a Human Fetus 33 The right svbclavian artery : The vertebral arteries : The thoracic duct : The right recurrent nerve :

4 34 H. Hanai, A. Ryiimon, K. Karnakura & S. Kaneko A d a c hi ('28) has classified branching patterns of arteries which rise from the aortic arch into seven types (A to G). The case in this paper corresponds to his G type. Prior to him, Ho 1 z a p f el (1899) also has classified anomalous cases of the right subclavian artery, rising from the aortic arch as the last branch, into ten types (I to X). The twenty-two cases in Japan belong to H o l z a p f e l's II, IV, V, VIII and IX types as follows : The frequency of this anomalous case reported in Japan is as follows : The authors wish to express their thanks to Professor Y. T a- n i g u c h i, their respected instructor, for guidance and encouragement shown to them. Literature Cited 1) Adach 1, B.; Das Arteriensystem der Japaner. Kyoto. Bd. 1, ) Holzapfe 1, G.; Ungewühnlicher Ursprung und Verlauf der Arteria subclavia dextra. Anat. Hefte, Bd. 12, ) K a w a n a, E. et al.; One case of the right subclavian artery as the last branch of the aortic arch. Acta anat. Nippon. Vol. 34, No. 6 (in Japanese). 4) K i t a g a w a, T. et al.; Unu kazo de la dekstra subklavikla arterio, originanta neordinare el l'aorto. Acta anat. Nippon. Vol. 37, No. 1, 31 (in Japanese). 5) K o d a m a, K.; Two cases of the right subclavian artery as the last branch from the aortic arch. Mitt. med. Akad. Kioto, Bd. 14, ) N a k a g a w a, M. ; On the right subclavian artery as the last branch of the aortic arch. Juzenkai Z. Vol. 44, No. 1, (in Japanese). 7) Omoch 1, S. et al.; One case of the right subclavian artery as the last branch of the aortic arch. Osaka Igk. Z. Vol. 41, No. 1, 3-8 (in Japanese).

5 Anomalous Origin of A. subclavia dextra in a Human Fetus 35. 8) S h i ma m o t o, 0; One case of the right subclavian artery from the aortic arch as the last branch. Nagasaki Igk. Z. Vol. 26, No (in Japanese). 9) T a n i g u c h i, Y.; An anomalous case of the right subclavian artery branching from the aortic arch as the last branch. J. Osaka med. college, Vol._ 2, No. 2, (in Japanese). 10) Um es u e, Y.; Anomaly of the branches of the aortic arch. Kyushu Igk._ Z. Vol. 2, No. 4, (in Japanese). Explanation of figures Fig. 1. Anterior view. The heart and lungs are removed. The esophagus and trachea_ are moved to the right. The branching part of the right common carotid from the arch is already removed by a preliminary dissection ( ). The branches from the arch are the right common carotid, the left common carotid and the left subclavian in order. The left recurrent nerve rounds beneath the arterial duct (/) and then ascends. Fig. 2. Anterior view. The esophagus and trachea are moved to the left. The right subclavian originates upward and to the right (\ ) from the posteromedial wall of the aorta in contact with the anterolateral surface of the body of the thoracic vertebra at the level between the second and third thoracic vertebrae. The subclavian sends the vertebral ( ), the internal thoracic and the thyreo cervical trunk ( ). The right vagus nerve is recognizable, though the right recurrent is lacking._ Fig. 3. Schematic illustration of this case. Key to Abbreviations rc Right common carotid artery lc Left common carotid artery rs Right subclavian artery Is Left subclavian artery ta Thoracic aorta i Internal thoracic artery a Arterial duct tt Thyreocervical trunk v Vertebral artery ry Right vagus nerve Iv Left vagus nerve r Recurrent nerve E Tr Esophagus Trachea Th II Second thoracic vertebra Th III Third thoracic vertebra

6 Anomalous Origin of A. subclavia dextra in a Human Fetus Plate Fig. 1. Fig. a Fig. 3 H. Hanai, A. Rytilmon, K. Kamakura & S. Kaneko