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Galen: Anatomy and Physiology

Galen: Anatomy and Physiology

Galen’s physiological system was, from the second century a.d. until the time of William Harvey, the basis for the explanation of the physiology of the body. His physiological theories are of particular interest because they included concepts of digestion, assimilation, blood formation, the maintenance of the tissues, nerve function, respiration, the heart beat, the arterial pulse, and the maintenance of vital warmth throughout the body—concepts which together formed a comprehensive and connected account of the functioning of the living animal body. His physiological system was based in large part on the work of such earlier anatomists as Aristotle, Praxagoras, Herophilus, and Erasistratus, but Galen made fundamental changes and additions to their theories and the resultant system was identifiably his own.

Aristotle had drawn attention to the role of the blood in forming the tissues of the developing embryo and a natural corollary of this role was that the blood should serve also to nourish and maintain the flesh of the adult body. Erasistratus had said that the food digested in the stomach and intestines was absorbed through the intestinal wall into the mesenteric veins as chyle, and the chyle was carried by these veins to the liver where it was transformed into blood. From the liver the blood was poured through the hepatic veins into the vena cava and thence distributed through the venous system to nourish the whole body. Galen adopted the same view. He considered the liver to be the chief organ governing the vegetative functions of the body, those functions which Aristotle said were governed by the vegetative soul. The liver attracted the blood-forming elements of the chyle and transformed them into blood; the gallbladder attracted those elements of the chyle unsuitable to form blood and discharged them as bile into the intestine. The bile was a by-product of blood formation.

Erasistratus had also thought that the blood which entered the right ventricle of the heart from the vena cava was prevented from returning by the tricuspid valve. The blood was then sent on via the pulmonary artery (or artery-like vein) to the lungs, which it served to nourish. Thus, the right ventricle and the pulmonary artery existed, according to Erasistratus, for nourishing the lungs, and Galen adopted the same view.

In order to study the distribution of the blood vessels Aristotle had advised that an animal intended for dissection should be killed by strangulation so as to retain the blood within the body. A result of this method of killing animals was that the left side of the heart and the arteries were left largely empty of blood. The arteries thus appeared as empty tubes running through the flesh, and Praxagoras of Cos had therefore distinguished them from the veins, or blood vessels, and had considered them to be air tubes. Erasistratus, working a generation or more after Praxagoras, in the early third century b.c., seems to have discovered and named the tricuspid and bicuspid valves guarding the entrances to the right and left ventricles of the heart respectively. He also understood that these structures functioned as valves, that is, as mechanical devices to allow the flow of materials in only one direction. Furthermore Erasistratus thought that the heart functioned like a bellows, that it distended itself actively in diastole, and the partial vacuum formed by the enlargement of the ventricles caused blood to flow into the right ventricle from the vena cava, and breath or pneuma to flow into the left ventricle from the lung through the pulmonary vein (vein-like artery). The contraction of the ventricles of the heart then forced blood from the right ventricle into the lungs and pneuma from the left ventricle into the arterial system. Thus, according to Erasistratus, the arterial pulse resulted from the filling of the arteries with pneuma by each contraction of the heart, and the arterial system served to convey pneuma to the whole body.

Erasistratus knew that when an artery was opened blood flowed from it, but he thought that the blood flowing from an opened artery was merely flowing through the artery from its principal reservoir in the veins. He considered that when an artery was opened the pneuma escaped from it, thereby creating a vacuum within its cavity and the blood then entered the artery from the veins through the synanastomoses, numerous minute, invisible passages connecting the arterial and venous systems throughout the body. He knew of the existence of the synanastomoses from the fact that when an animal was bled to death from an opened artery all of the blood in the veins was also drained away. Since there was no visible connection between the arterial and venous systems there must be a multitude of invisible connections. Erasistratus thought that these connections were normally closed, but that they opened in fevers when the presence of blood in the arteries was indicated by a flushed skin and a throbbing pulse. Similarly the opening of an artery in an animal created an abnormal and pathological condition which permitted blood to flow from the veins into the arteries.

The fundamental change which Galen made in the physiology of the heart, lungs, and vessels was to show that both the left ventricle of the heart and the arteries invariably contain blood and that this is their normal condition, not a sign of disease. By his demonstration of the normal presence of blood in the arteries, Galen destroyed Erasistratus’ theory of how the pneuma was conveyed to the whole body.

Galen’s proof of the normal presence of blood in the arteries is contained in his short work Whether Blood Is Contained in the Arteries in Nature. He observed that if Erasistratus were right that the pneuma escaped when an artery was opened the pneuma should be seen to escape first before the blood poured forth, but in fact the blood pours forth at once. Yet the pneuma, according to Erasistratus, was simply air taken into the body in breathing so that it could not be such a rarefied substance that all of the pneuma in the body could escape instantaneously through a mere pinprick in an artery. Galen also observed the presence of blood in the arteries of the transparent mesentery, and then he showed experimentally that when he isolated a portion of an artery in a living animal—he tied it off with ligatures so that no blood could flow into it from elsewhere and then opened it—he always found it full of blood. By opening the chest of a living animal he demonstrated that blood was present in the left ventricle of the heart.

Galen then had to devise new theories to account for the functions of the heart and arteries. He supposed that the prime function of respiration was to cool the excess heat of the heart. Since the lungs surround the heart in the chest cavity they might by that fact alone exert a cooling influence on the heart. In addition air might pass from the lungs along the pulmonary vein into the left ventricle, and there serve both to nourish and cool the innate heat of the heart and then return to the lungs accompanied by something like smoke. The pulse in the arteries was generated from the heart. In accounting for the arterial pulse Galen adopted an idea suggested originally by Herophilus that when the heart was in diastole a wave of dilatation passed along the walls of the arteries. The arteries thus dilated drew into themselves blood from the veins through the synanastomoses and pneuma from the surrounding air through pores in the skin. Thus the arterial pulse caused the whole body to breathe in and out and and served to nourish the innate heat throughout the body. If the pulse were cut off from a limb by a ligature, the limb became pale and cold, because, according to Galen, its innate heat was no longer nourished by the vital pneuma drawn into the arteries by the pulse.

Galen was obliged by his theory to suppose that the mitral valve, opening into the left ventricle of the heart, did not act as Erasistratus had seen that its structure would require it to act, as a device to allow the flow of materials in one direction only, into the heart. Since the mitral valve had only two flaps Galen argued that it would allow the return of air and smoky vapors from the heart to the lungs. In the right ventricle of the heart, however, Galen considered that the tricuspid valve with its three flaps was a tight valve. Blood entering the right ventricle from the vena cava could not return. Some of it passed through the pulmonary artery (artery-like vein) to the lungs, but since the pulmonary artery was smaller than the vena cava Galen thought that it could not remove all of the blood entering the right ventricle. Therefore, he said, some blood must pass through the interventricular septum into the left ventricle. Since there were synanastomoses between the venous and arterial systems throughout the body Galen thought they should also be present in the septum and in this way he explained how the left ventricle was supplied with blood. However, in his work On the Usefulness of the Parts of the Body, Galen considered that both ventricles contained both blood and pneuma, but that the left ventricle contained pneuma in larger proportion.

Although physiology remained for fourteen centuries after Galen’s death basically Galenic it did not always coincide exactly with what Galen had taught. Galen had developed his theories in close relation to those of his predecessors, particularly Herophilus and Erasistratus, and he was not able to free them completely from inconsistencies. Furthermore, he frequently contradicted himself in different works. Galen’s successors, in attempting to make his physiology simpler and more consistent, tended to revert to Erasistratus’ view that the left ventricle of the heart and the arterial system contained pneuma rather than blood.

In his work On the Doctrines of Hippocrates and Plato Galen defened plato’s concept of a tripartite soul (that is, a nutritive soul, an animal soul, and a rational soul) against the Stoic doctrine of the soul as single and indivisible. Galen showed that in his physiological system the liver and the veins supplied the body with nutrition, the lungs, the left ventricle of the heart and the arteries maintained the pneuma and the innate heat throughout the body, while the brain and nerves controlled sensation and muscular movement through the medium of a special psychic pneuma. The later systematizers of Galen held that there were three kinds of pneuma or spirits corresponding to these three functional systems: the natural spirits formed in the liver, the vital spirits formed in the heart and arteries, and the animal spirits formed in the brain.

Leonard G. Wilson


1. Cf. W. Crönert. “Klaudious Galenos,” in Mitteilungen zur Geschichte der Medizin und der Naturwissenschaften und der Technik, 1 (1902), 3 f.; K. Kalbfleisch, “Claudius Galenus,” in Berliner philologische Wochenschrift, 22 (1902), 413.

2. J. Ilberg, “Aus Galens Praxis,” in Neue Jahrbücher für das klassische Alterturn, 15 (1905), 277, n.1.

3. J. Walsh, “Date of Galen’s Brith,” in Annals of Medical History, n.s. 1 (1929), 378–382.

4. Ilberg, “Wann ist Galenos geboren?” in Sudhoffs Archiv, 23 (1930), 289–292.

5. Walsh, “Refutation of Ilberg as to the Date of Galen’s Birth,” in Annals of Medical History, n.s. 4 (1932), 126–146.

6. Crönert, p.4.

7. H. Diller, “Nikon 18,” in pauly-Wissowa, Real-Encyclopädie, XVII, pt.I (1936), col 507 f.

8. Galen V. 40 f.; here and following, references are, if not otherwise stated, to the Kühn ed.

9. Cf. I. Veith,“Galen, the Frist Medical autobiographer,” in Modern Medicine (Minneapolis), 27 (1959), 232–245.

10. G. Misch, Geschichte der Autobiographie, 4 vole., 3rd, ed., enl., I, pt. 1 (Bern. 1949)

11. Cf. ibid., p. 344.

12. See the enumeration of these by J. C. G. Ackermann, in Galen I. xxi, n. A.

13. See M. Meyerhof, “Autobiographische Bruchstücke Galens aus arabischen Quellen,” in Sudhoffs Archiv, 22 (1929), 72–86.

14. Cf. Galen XIX, 46.

15. G. Sarton, Galen of Pergamon (Lawrence, Kans., 1954).

16. P. Diepgen, Geschichte der Medizin (Berlin, 1949), I. 119 ff.

17. K. Deichgrabe, Galen als Erforscher des menschlichen Pulses (Berlin, 1957), p. 32.

18. Diller, col. 507, I, 20 ff.

19. Galen V. 41 f.; cf X. 561, 609. A list of his teachers in philosophy is given in E. Groag and A, Stein, Prosopographia imperii Romani, 4 vols., 2nd ed., (Berlin, 1952). IV, art. G24

20. Galen X. 609.

21. See F. Kudlien, “Medical Education in Classical Antiquity,” in C. D. O’Malley, ed., History of Medical Education (Berkeley-Los Angeles London, 1970). p. 35, n. 83.

22. Cf. Sarton, p. 17; and Misch, p. 346.

23. Galen XIX. 57.

24. ibid., II. 224.

25. Cf. G. W. Bowersock, Greek Sophists in the Roman Empire (Oxford, 1969), pp. 60 f.

26. Ibid., pp. 61 f.

27. Ibid., ch. 5. Passim.

28. Galen XIX.16

29. Ibid; the treatise On Medical Experience is edited by R. Walzer (London-New York-Toronto, 1944).

30. Walzer, Galen on Medical Experience, p. 87; and p. viii, n. 5.

31. I. von Müller, “Über die dem Galen zugeschriebene Abhandlung Peri tes aristes haireseos,” in Sitzungsberichte der Bayerischen Akademie (1898), pp. 53–162.

32. Galen XIX. 8 f.

33. See H. Diels, “Die Handschriften der antiken Ärte,” in Abhandlungen der Preussischen Akademie (1906). p. 129.

34. See A. Stein, “Calvisius 6,” in Pauly-Wissowa, III. pt. 1 (1867), 1410.

35. Galen I. 274.2–279.5.

36. Ibid., XIX. 40.

37. On the chronology of Galen’s writings, see Ilberg. “Über die Schriftstellerei des Klaudios Galenos,” in Rheinisches Museum, 44 (1889), 207–239, 47 (1892), 489–514; 51 (1896). 165–196; and 52 (1987), 591–623, See also K. Bardong. “Beiträge zur Hippokrates- und Galenforschang. Teil 2,” in Nachrichien. Akademic der Wissenschaften in Göttingen. Phil.-hist Kl., 7 (1942), pp. 603–640.

38. Galen VI, 756.

39. Ibid., II. 217.

40. Ibid., XIX. 16.

41. Cf. Deichgräber, pp. 33–36; “Zu Galen als Platoniker.”

42. Galen II. 217.

43. On Galen’s Alexandrian period, see Walsh, “Galen’s Studies at the Alexandrian School,” in Annals of Medical History,9 (1927), 132–143.

44. Cf., for example, J. Mewaldt, “Galenos 2,” in Pauly-Wissowa, VII, pt. I (1910), 579, lines 20 f.

45. Galen II. 217 f.

46. For this, cf. Kudlien, “Autike Anatomic und menschlicher Leichnam,” in Hermes, 97 (1969), 79 f.

47. For this, cf. Kudlien. in O’Malley, pp. 36. notes 97, 98.

48. Galen XIII. 599.

49. The early Diagnosis of Diseases of the Eye apparently had its source in practical experience; see Galen XIX. 16.

50. Cf. Galen XIII. 599 ff.

51. Ibid., II. 215.

52. Inid., XVIIIA. 347.

53. On what follows, cf. Mewadt. p. 579, lines 30 ff.; and Bowersock, pp. 62 ff., 82–84.

54. See Galen II. 216.

55. For this, cf., for example, Kudlien, Die handschrifiliche Überlieferung des Galenkommentars zu Hippokrates De articulis (Berlin, 1960), pp. 19 f. In this special case, the earlier as well as the later, “official” version can be reconstructed from the manuscript tradition.

56. Cf. Kudlien, in O’Malley, pp. 20, 35, notes 84 and 85.

57. Galen VIII. 144.

58. Cf. Bowersock, p. 67.

59. Cf. Kudlien, “The Third Century A.D.—A Blank Spot in the History of Medicine?” in L. G. Stevenson and R. Multhauf, eds., Medicine, Science and Culture: Historical Essays in Honor of Owsei Temkin (Baltimore, 1968). pp. 32 f.

60. Wilamowitz later revised his judgment; see Deichgräber, p. 33.

61. For them, see Bowersock, ch. 7.

62. See Mewaldt. p. 579, lines 55 ff.

63. See J. Kollesch.“Galen und seine ärztichen Kollegen,” in Das Altertum, 11 (1965), 47–53.

64. For this and what follows, see Galen XIX. 15.

65. Cf. Deichgräber p. 33.

66. Galen XIV, 622, 624.

67. Ibid, pp. 647 f.

68. Ibid, XIX, 15.

69. Walsh, “Refutaion of the Charges of Cowardice Made Against Galen,” in Annals of Medical History. n.s. 3 (1931), 195–208.

70. For a negative interpretation of his flight from Rome, see Ilberg, “Aus Galens Praxis” reprinted in H. Flashar, ed., Antike Medizin (Darmstadt. 1971). pp. 388 f.

71. On this and what follows, cf. Mewaldt. p. 580, lines 37 ff.

72. Cf. P. E. M. Berthelot, “Sur les voyages de Galien et de Zosime dans l’Archipel et en Asie et sur la matière médicale dans l’antiquite,” in Journal des savants (1895), 382–387.

73. Bowersock, p. 66.

74. Ibid., pp. 63 f. Some questions dealing with Galen’s accomplishments as court physician are discussed in Kollesch, “Aus Galens Praxis am römischen Kaiserhof,” in E. C. Welskopf. ed., Neue Beiträge zur Geschichte der alten Welt, II. 57–61.

75. On this and what follows, see Mcwaldt, p. 580, lines 55 ff.

76. Cf. W. Pagel’s review of May’s trans. of On the Usefulness of the Parts of the Body, in Medical History,14 (1970), 408.

77. Cf. W. Schöner, Das Viererschema in der antiken Humoralpathologie (Wiesbaden, 1964), pp. 86 ff., esp. 92.

78. For an evaluation of Galen’s anatomy, see, for example, O. Temkin and W. L. Strauss, “Galen’s Dissection of the Liver and of the Muscles Moving the Forearm,” in Bulletin of the History of Medicine, 19 (1946), 167–176.

79. For an evaluation of Galen’s physiology, see, for example, O. Temkin, “On Galen’s Pneumatology,” in Gesnerus,8 (1961), 180–189; “A Galenic Model for Quantitative Physiological Reasoning?” in Bulletin of the History of Medicine, 35 (1961), 470–475; and “The Classical Roots of Glisson’s Doctrine of Irritation,” ibid, 38 (1964); 297–328.

80. See Sarton, pp. 56 ff.

81. See L. Edelstein. “The Dietetics of Antiquity,” in Ancient Medicine, Selected Papers of Ludwig Edelstein. O. and C. L. Temkin, eds. (Baltimore, 1967). pp. 303–316.

82. Mewaldt. p. 585, lines 53 ff.

83. Cf Galen, in Corpus medicorum Graecorum V. pt. 9. 1. 7 f.

84. Cf. Kudlien, Die handschriftliche Überlieferung, pp. 19 f.

85. Cf. L. Bröcker, “Die Methoden Galens in der literarischen Kritik,” in Rheinisches Museum, 40 (1885), 415–438.

86. Cf. Galen, in Corpus Medicorum Graecorum, V, pt. 10, 2, 2, p. 413, lines 37 f.

87. Cf. Mewaldt, p. 586, lines 9 ff.

88. See Kudlen, “Wie erkannten die antiken Ärzte einen Simulanten?” in Das Altertum7 (1961), 226–233.

89. C. Lichtenthacter, Quatrième série d’études hippocratiques (VII-X) (Geneva, 1963), pp. 109–135.

90. R. Joly, Le niveau de la science hippocratique (Paris, 1966), p. 234.

91. See Mewaldt. p. 585, lines 23 ff.

92. Cf. H. Koelbing, Der Urin im medizinischen Denken, pt. 5: “Die antiken Grundlagen der Harnschau,” Documenta Geigy (Basel, 1967), passim.

93. Cf. Rothkopf, Zum Problem des Irrationalen in der Medizin der römischen Kaiserzeit (Kiel, 1969), 8 f., 16–19.

94. On other achievements of Galen in gynecology, see Ilberg, in Flashar, pp. 383 f., 408.

95. On what follows, see M. Michler, Das Spezialisierungsproblem und die antike Chirurgie (Bern-Stuttgart-Vienna, 1969), 50 ff.

96. Cf. O. Temkin, “Greek Medicine as Science and Craft,” in Isis,44 (1953), 224 f.

97. Michler, p. 62.

98. Cf. Mewaldt, p. 588, lines 42 ff.

99. See I. von Müller, “Galen Philologe,” in Verhandlungen der 41. Versammlung deutscher Philologen und Schulmänner (Munich, 1891). pp. 80–91.

100. See Mewaldt, p. 589, lines 9 ff.

101. G. Strohmaier, “Galen als Vertreter der Gebildetenreligion seiner Zeit,” in Welskopf, II, 375–379.

102. Cf. R. Walzer, Galen on Jews and Christians (Oxford, 1949).

103. Cf. Deichgräber, p. 35.

104. See Sarton, p. 56; on Galen’s religiosity, see pp. 82 ff.

105. See V. Schöllkopf, Zum Problem der Religiosität älterer griechischer Ärzte (Kiel, 1968).

106. Cf. Ilberg, in Flashar, p. 365.

107. Cf. Kudlien, “Zum Thema ‘Homer und die Medizin,’” in Rheinisches Museum, 108 (1965), 299.

108. See M. Issa. Die “galenische’ schrift “Über den Plötzlichen Tod” (Kiel, 1969).

109. It is to be hoped that O. Temkin will continue his “Studies on Late Alexandrian Medicine” (cf. Bulletin of the History of Medicine, 3 [1935], 405–430) and therein deal with the problem of the Summaria Alexandrina.

110. Cf. Kudlien, in Stevenson and Multhauf, pp. 29 f.

111. Cf. G. Bergsträsser, Neue Materialien zu Hunain Ibn Ishaq’s Galen-Bibliographie (Nendeln, Liechtenstein, 1966) 95–98.

112. Cf. H. Diels, “Bericht über das Corpus Medicorum Graecorum,” in Sitzungsberichte der Preussischen Akademie der Wissenschaften zu Berlin (1914) p. 128.

113. Ibid. (1913), p. 115; (1915), pp. 92 f.; and (1916), pp. 138 f.

114. Whether Epigenes—to whom Galen dedicated On Progranosis—was a doctor is not certain. Cf. Ilberg, in Flasher, p. 375.

115. On this and what follows, see Kudlien, in Stevenson and Multhauf, pp. 27 f.

116. See, L. Thorndike, “Translations of the Works of Galen From the Greek by Peter of Abano,” in Isis,33 (1942), 649–653.

117. See Thorndike, “Translations of the Works of Galen by Nicola da Reggio,” in Byzantina Metabyzantina1 (1946), 213–235; cf. I. Wille, “Überlieferung und Übersetzung. Zur Übersetzungstechnik des Nikolaus v. Rhegium in Galens Schrift De temporibus morborum,” in Helikon, 3 (1963), 259–277.

118. Cf. M. Meyerhof, “Les versions syriaques et arabes des écrits Galeniques,” in Byzantion, 3 (1926), 33–51.

119. Cf. Bergsträsser, Human Ibn Ishaq: Über die Syrischen und arabischen Galenübersetzungen, repr. (Nendeln, 1966).

120. Cf. R. J. Durling, “A Chronological Census of Renaissance Editions and Translations of Galen,” in Journal of the Warburg and Courtauld Institutes,24 (1961), 230–305.

121. Cf. H. Heinrichs, Die Überwindung der Autorität Galens durch die Denker der Renaissancezeit (Bonn, 1914).

122. See Bachmann, “Neo-Galenismus,” in Janus, 7 (1902), 455–459.


The only complete ed. of Galen (Greek text with Latin trans.) is C.G. Kühn, Claudii Galeni Opera Omnia, 20 vols. (repr., Hildesheim, 1964–1965). The Greek text of this ed. is very defective. The Corpus Medicorum Graecorum, in its Abt. V and in supplementary vols., is publishing a series of philological-critical eds. of Galenic writings.

The Galenic MSS (for original texts and translations) are listed in H. Diels, “Die Handschriften der antiken Ärzte, Griechische Abteilung,” in Abhandlungen der königlich Preussischen Akademie der Wissenschaften (Berlin 1906), pp. 58–158; a supp. is ibid (1907), 29–41. See also R. J. Durling, “Corrigenda et Addenda to Diel’s Galenica”, in Traditio, 23 (1967), 461–476.

There is no complete trans. of the works of Galen in a modern language. Among the English trans. of individual writings are On Anatomical Procedures, Charles Singer, trans. (Oxford, 1956), the surviving books; and W. L. H. Duckworth (Cambridge, 1962), the later books; On the Natural Faculties, A. J. Brock, trans., Loeb Classics (London-Cambridge, Mass., 1952); Hygiene, R. M. Green, trans. (Springfield, Ill., 1951); On the Passions and Errors of the Soul, P. W. Harkins and W. Riese, trans. (Columbus, Ohio, 1963); On the Usefulness of the Parts of the Body, M.T. May, trans., 2 vols. (Ithaca, N.Y., 1968); and On Medical Experience, R. Walzer, trans. (London-New York-Toronto, 1944), based on the 1st ed. of the Arabic version.

The most extensive modern bibliography is K. Schubring, in the Kühn ed., XX, xvii-Ixii.

See also Jerome J. Bylebyl, Cardiovascular Physiology in the Sixteenth and Early Seventeenth Centuries, unpub. doctoral diss. (Yale University, 1969), pp. 10–137; Donald Fleming, “Galen on the Motions of the Blood in the Heart and Lungs,” in Isis,46 (1955), 14–21; and Leonard G. Wilson, “Erasistratus, Galen and the Pneuma,” in Bulletin of the History of Medicine, 33 (1959), 293–314.

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