The Collaborative International Dictionary of English v.0.48:
Epicranium \Ep`i*cra"ni*um\, n. [NL. See Epi-, and Cranium.] 1. (Anat.) The upper and superficial part of the head, including the scalp, muscles, etc. [1913 Webster] 2. (Zo["o]l.) The dorsal wall of the head of insects. [1913 Webster]WordNet (r) 3.0 (2006):
epicranium n 1: the muscle and aponeurosis and skin covering the cranium