The nervous system in antiquity (A)


This overview of the nervous system in antiquity shows  that whereas neuro-anatomy had its heyday in the 4th and  3rd centuries BC (the Alexandrian School) and was later  consolidated by Galen in the 2nd century AD, neurophysiology remained largely mired in erroneous concepts. While the  descriptions of neurological disease often produced quite
apt clinical pictures, poor understanding of pathophysiology  resulted in ineffectual therapy. The embryonic origins of  modern neurology lie in the gradual evolution of neuroanatomy  and neurophysiology in antiquity. Closely allied  to the early understanding of the nervous system was the  contested issue of where the control centre of the body
(hegemonikon) was located. These are the issues that we review. 

The body’s control centre
The need to place all actions of the body under the control of  a single centre or principle (hegemonikon – a term coined by  the Stoics) was pervasive in Western antiquity.1 Although the  head (brain) was favoured by many, entities such as the chest,
heart, liver, blood and the pneuma (‘vital spirit’) also had their supporters. Hippocrates stated that the diaphragm, which was  favoured by some, could not be seriously considered because it  did not contain a cavity2 (presumably to house the soul or ‘vital  spirit’).
In Ancient Egypt, the heart was considered to be the chief  organ of the body. The brain was viewed as being of little  importance – at best, the producer of mucus during illness,
subsequently discharged through the nose.3,4 In Mesopotamia,
the liver was thought to be the seat of the soul.5 In Greece, the so-called Presocratic philosopher-physicians (6th and 5th  centuries BC) laid the foundation of empirical science that led  to the Hippocratic era. Alcmaeon of Croton, a contemporary  of Pythagoras, favoured the head (and brain), as did Diogenes  and Democritus.6 Parmenides6 and the influential Sicilian,Empedocles,1 however, thought that the soul was seated in the  thorax or the blood surrounding the heart.
The Hippocratic Corpus (mainly 5th and 4th centuries BC) presented divergent views. In The Sacred Disease (chapter 19),the brain is called the centre of bodily functions but, in a later  text (The Heart, chapter 7), the left ventricle of the heart is the  seat of the soul. In Diseases Book II, higher bodily functions are  ascribed to both the heart and the brain.
While Plato favoured the head, Aristotle placed the  hegemonikon in the heart, stating that a bloodless brain could  not house the soul. During the 4th century BC, the Stoics,
Epicurians, Praxagoras and Diocles all nominated the heart,while Strato placed the seat of the soul between the eyebrows.
At the onset of the Hellenistic era (late 4th century BC), the  cardiocentric consensus (heart as control centre) gradually receded, as influential Alexandrians such as Herophilus
and Erasistratus brought evidence of an encephalocentric  hegemonikon.1 Erasistratus thought it might be located in the meninges rather than the brain.1 Chrysippus (3rd  century  BC), however, still favoured the heart,7 while Asclepiades (1st  century BC) taught that there was no hegemonikon, since the  senses controlled all bodily activities.1
In the Roman era, influential figures such as Galen1 and Rufus (2nd century AD)7 strongly defended the  encephalocentric approach, but Lucretius (1st century BC) and Alexander of Aphrodisias (2nd century AD)1 were  cardiocentrists, defending a point of view that persisted  through medieval times and was still reflected by Shakespeare  in his play The Merchant of Venice (III.ii.63): ‘Tell me where is  fancy bred, or in the heart, or in the head’?8
Phrases such as ‘heart and soul’, ‘with all my heart’ and  ‘heartfelt grief’ have their origin in the cardiocentric view of  the past.

Neuro-anatomy
In Ancient Egypt, the brain was considered unimportant and  there was no real knowledge of the nervous system. During the  mummification process, the brain was destroyed and removed  via the nose and through the cribriform plate.3 But in the  Edmund Smith Papyrus, the brain is identified as an organ,4and limited neuro-anatomical features such as the meninges,cerebrospinal fluid, surface blood vessels and convolutions,
which were observed through open skull wounds, are   mentioned.3 Similarly, Mesopotamian writings reveal no  significant neurological knowledge.7

Greece (Classical era)
In pre-Hippocratic times, the philosopher-physician Alcmaeon  of Croton (6th century BC) probably took the first tentative  steps towards exploring the brain and nervous system. He  possibly dissected animals, and was said to have examined an  excised human eye. He linked the senses functionally to the  brain and postulated passages connecting the eyes, ears, nose  and tongue (taste) with the brain. He might have described the  optic nerve.1
The Hippocratic Corpus (the foundation document of  empirical medicine) contains little on neuro-anatomy,knowledge of which was gained from general observation and  limited animal (but no human) dissection.1 Two membranes covering the brain (the dura and pia mater, but not the  arachnoid) were described; these membranes partially divide
the brain down the middle into the right and left hemispheres.
Apparently based on dissection of the goat, the brain was said  to be oedematous and foul-smelling.1,2 The spinal cord was ribed as attached to the brain and of the same consistency,differing from that of bone marrow. The fluid under the brain Membranes (meninges) was found to be confluent with thatCovering the spinal cord.9 Passages through the skull and  eninges linking the eyes and ears to the brain were noted,
but no such passage to the nose. Blood vessels, ducts andNerves were confused – phlebes were described as hollowtubes carrying various fluids, and neura were solid structures
(including nerves, tendons and ligaments). Semen was believedto originate in the head and to be conveyed in neura. The eyewas thought to consist of three tunics (sclera, choroid and
retina) and to be nourished by the brain through the hollowoptic nerve.9
Although not medically trained, Aristotle (4th century BC)performed extensive animal dissections and confirmed thatthe main brain consisted of two hemispheres. He described
a lesser brain (parenkephalon (cerebellum)) behind the mainbrain (encephalon (cerebrum)). The brain was thought to becovered by two meninges and to contain few blood vessels. Healso found that some animals had small cavities (ventricles)
in the cerebrum, and mentioned the presence of a few nervesoriginating in the brain (cranial nerves).1 The concept of theneuron still included tendons and ligaments besides nerves.He reported that men had larger brains than women and that,
relative to body size, man had the largest brain of all creatures.7
Praxagoras (4th century BC) claimed that blood vesselsterminated as nerves, so supporting the argument that the heartwas the central controlling organ.7 He and Philotimus believedthat the brain was merely an outgrowth of the spinal cord.1
Vindicianus later wrote that Diocles (4th century BC, sometimescalled the second Hippocrates) had said that the right half ofthe brain controlled sensation and the left side, intelligence.10

 

(TO BE CONTINUED)

François P Retief, Louise Cilliers

François Retief is former Dean of the Medical School of the  University of the Free State and Rector of MEDUNSA. He has  retired as Rector of the University of the Free State, where he is currently a Research Fellow.
Louise Cilliers is Senior Professor and Head of Classical  Languages at the University of the Free State, and Editor of Acta  Classica.

NOTES

1. Rocca J. Galen on the Brain. Leiden: Brill, 2003: 17-63, 77-188, 254-356.
2. Hippocrates. The Sacred Disease, ch 6: 17-19.
3. Nunn JF. Ancient Egyptian Medicine. Norman: University of Oklahoma Press, 1996: 43-93, 179.
4. Sigerist HE. A History of Medicine. Vol. I. New York: Oxford University Press, 1955: 353.
5. Major RH. A History of Medicine. Springfield: Charles Thomas Publishers, 1954: 31, 200-211.
6. Von Staden H. Herophilus. Cambridge: Cambridge University Press, 1989: 159-206, 248, 314.
7. Clark E, O’Malley CD. The Human Brain and Spinal Cord. Berkeley: University of California
Press, 1968: 1-18, 141-150.
8. Clarke E, Dewhurst K. An Illustrated History of Brain Function. Oxford: Sandford Publishers,
1972: 2-8.
9. Hippocrates. Places in Man, 2.1-3, 3.5, 4.0, 10.2, 32.1.
10. Longrigg J. Greek Medicine from the Heroic to the Hellenistic Age. London: Duckworth, 1988: 69,76, 86-88, 107.

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