The trigeminal nerve supplied muscles share many traits due to their common embryological derivation from the mandibular branchial arch. Many of these muscles, especially the masticatory, exhibit very complex intra- and intermuscular anatomical and functional specializations which continue to be investigated. Two schemes have been proposed to classify the intramuscular and extramuscular slips associated with these muscles: 1) based on recognizable laminae within each muscle; 2) based on the pattern of nerve distribution to definable parts of each muscle. The extramuscular slips have been identified on the bases of their nerve supply. The second scheme is beginning to yield results which confirm Edgeworth’s (1914, 1935) hypothesis regarding the ontogeny and phylogeny of the trigeminal nerve supplied musculature. These advances in the rational classification of these muscles have resulted from improved methods to expose the deeper parts of the masticatory and related spaces. However, because of the piecemeal exposure of parts of the spaces which contain some of the deeper trigeminal muscles there remain several issues that still need to be resolved. We provide a detailed protocol by which all the trigeminal nerve supplied muscles can be isolated from the upper cranium so that the entire mandibular nerve tree along with its musculature may be described as a connected complex of related structures. The practical and clinical implications of this new methodology are evaluated and discussed.