[24]Edwardes is obviously aware of the individuality of each pleural sac.
[25]The pericardium.
[26]Note that the heart is the most important organ of the body.
[27]The three-ventricled heart was a myth which remained entrenched in anatomy until Niccolò Massa (1536) and Vesalius. Leonardo da Vinci showed that there were only two ventricles but his drawings were not seen by his contemporaries.
[28]Edwardes is to a degree correct when he says that life remains longest in the auricles. Slow contraction of the auricles can be seen for a short time after contraction of the ventricles has ceased. This passage could suggest that he practised vivisection.
[29]Note the persistence of the old idea that the left ventricle contains air.
[30]The medieval anatomists regarded the right and left atria as part of the corresponding ventricle, hence they stated that the venae cavae opened into the right ventricle. Edwardes’s acceptance of the old theory is interesting for just above this in the text he mentions the auricles as separate chambers.
[31]Galen taught that the nerves were hollow and carried the animal spirit from the brain to the periphery. The vital spirit (air) was carried by the arteries to the brain where, in the rete mirabile it was transformed into the animal spirit.
[32]The ancient idea that there were seven pairs of nerves did not disappear from anatomical teaching until Thomas Willis in 1664 increased the number to nine and Samuel Thomas Soemmerring in 1778 established the modern order of numbering the nerves into twelve pairs. In the account which follows Edwardes does not follow the ancient description of the cranial nerves. According to Galen, and indeed Vesalius, the olfactory nerves were not regarded as separate entities; moreover the glossopharyngeal, vagus, and accessory nerves were part of a single nerve. Edwardes does not describe the trigeminal or facial nerves nor the trochlear or abducent. The trochlear nerve had been described by Alessandro Achillini in 1520. The abducent nerve was to be described later by Eustachius.
[33]Olfactory nerves. That Edwardes regarded them as functional units is worthy of note.