Two things are notable regarding the said question: The first one is that the knowledge of Allah is definite. The changes and revolution of time do not have any effect on HIm, while the scientific theories are merely hypothetical and conjectural. That is why the scientists have established a number of views on their research but later the research changed and the theories also changed. The movement and stillness of the earth and the sky and the Darwin’s theory of evolution may be produced as an example. Hence, if the holy Quran refutes the scientific theory of Hippocrates, one cannot put any objection by it on the holy Quran, because the scientific theory is not an eternal theory. In fact, changes may occur in it and may go wrong. But, what the holy Quran says is eternal and no changes can take place in it. The truth shall be what the holy Quran says.
The second is that there is no contradiction between what the holy Quran and the theory of Hippocrates. Because يخرج من بين الصلب والترائب (86-7) does not mean that the sperm originates from the mid-gut section of a man’s body as you wrote but sulb (chest) and trayib (back) indicates towards the complete body. This is completely understood by what Hadhrat Maulana Ashraf Ali Thanvi (رحمة الله عليه) wrote in the commentary of this ayat: “He is created of spouting water that comes out from between the loins and the chest-bones, i.e. from all body. Since the chest and back are both the sides of the body by all body was meant. And this is meant for the reason that the sperm is created in the complete body and then takes effect. And chest and back was specially mentioned perhaps because the chief body parts i.e. heart, brain, and liver play important role in generating the semen. The connection of heart and liver is obvious from back and the connection of brain from chest through medulla. (Bayan al-Quran, Vol. 12, p. 92, Taj Publishers Delhi)
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband