Craniofacial Muscles

254 Z.-J. Liu
Fig. 14.10 Comparison of tongue morphology and its relation to mandibular dentition 4 weeks
after the surgery. Top : Tongue received sham surgery; Bottom : Tongue received reduction surgery.
Note that the remarkable decreases in length and width ( double-arrowed red lines ) in the reduction
as compared to the sham tongues (from Perkins et al. 2008 , with permission)
The tongue cast and postmortem measurements further indicate that despite ongoing
growth (compare before and after in sham-surgery animals in Table 14.1 ), the reduction
surgery signi fi cantly reduces the length and width of tongue body, and results
in about 15% loss of both volume and weight of the tongue over a 4-week period
postoperatively (Perkins et al . 2008 ) .
Although complete healing of surgical incisions is seen from the tongue surface
(Fig. 14.10 ), muscle fi ber reconstitution does not occur histologically in the surgical
site. Instead, disorganized collagen fi bers are interwoven without any detectable
arrangement or orientation. A few atrophied myo fi bers with reduced perimysium
and endomysium are sporadically distributed in fi brous tissue (Fig. 14.11 ). These
features are typical signs of fi brosis. Therefore, the recovery of normal muscular
architecture and functionality is compromised (Perkins et al . 2008 ) . The formation
of fi brosis may cause further decreased muscle contractility and reduced range of
kinematics. A cell proliferation assessment study (Ye et al . 2010 ) further revealed
that like other skeletal muscles, myogenic regeneration in the tongue follows a centripetal
gradient that fl ows from outer to inner regions, showing most and least