Examination of nerve distribution to masticatory muscles using a silicone permeation technique

The detailed anatomical distribution of nerves throughout the human body has generally been studied by dissection of fixed cadavers in liquid. In this traditional method, it is difficult to maintain the position of nerves on their respective muscles. It is also difficult to keep the distributed form of the nerves. To understand the morphology of nerves, it is essential to determine their location and distribution precisely. In this study the masseter muscle was removed from a cadaver after fixation with formalin. The muscle was then permeated with silicone using the following procedure. The muscle fixed by 10% formalin was dehydrated with alcohol. After dehydration, alcohol was replaced with methylene chloride. The sample was permeated by silicone in a permeater. Following dissection, enamel was applied to the nerve by hand to fix its position. This new permeation method provided excellent localization of nerves innervating the muscle and has the added advantage of providing a three-dimensional structure of neural anatomy similar to the casting procedures used to visualize blood vessels.