I have been researching the Sakkatsu (殺活 - lethal & reviving) techniques in Ryōi Shintō-ryū Kyuyo no maki (良移心當流 九要之巻 - Ryōi Shintō-ryū nine main points scroll).

I referenced the illustrations of the visceral, circulatory and neurological systems of the body in Fujita Seiko's (藤田 西湖) book: 'Kenpō gokui atemi sappō kappō meikai'(拳法極意当身殺法活法明解 - Kenpō secrets of striking, lethal method, revival method clear explanation) republished 1993.

I then compared the above with descriptions of blunt force trauma injuries, as described in 'Atlas of Trauma: Operative Techniques, Complications and Management' by Ferrada & Ferrada (2020). It was interesting to note that many of the points described in the 'Kyuyo no maki' are indeed areas where blunt force trauma (such as striking) can result in death if untreated, or if there are complications.