Four human soft palate muscles, and palatopharyngeus, the uvula, the levator and tensor veli palatini were
examined using enzyme-histochemical, immunohistochemical and biochemical methods and compared with
human limb and facial muscles. Our results showed that each palate muscle had a distinct morphological
identity and that they generally shared more similarities with facial than limb muscles. The
palatopharyngeus and uvula muscles contained 2 of the highest proportions of type II fibres ever reported
for human muscles. In contrast, the levator and tensor veli palatini muscles contained predominantly type I
fibres. A fetal myosin heavy chain isoform (MyHC), not usually found in normal adult limb muscles, was
present in a small number of fibres in all palate muscles. The mean muscle fibre diameter was smaller than
in limb muscles and the individual and intramuscular variability in diameter and shape was considerable. All
palate muscles had a high capillary density and an unusually high mitochondrial enzyme activity in the type
II fibres, in comparison with limb muscles. No ordinary muscle spindles were observed. The fibre type and
MyHC composition indicate that the palatopharyngeus and uvula muscles are functionally involved in quick
movements whereas the levator and tensor veli palatini muscles perform slower and more continuous
contractions. The high aerobic capacity and the rich capillarisation suggest that the palate muscles are
relatively fatigue resistant. Absence of ordinary muscle spindles indicates a special proprioceptive control
system. The special morphology of the palate muscles may be partly related to the unique anatomy with
only one skeletal insertion, a feature consistent with muscle work at low load and tension and which may
influence the cytoarchitecture of these muscles. Other important factors determining the special
morphological characteristics might be specific functional requirements, distinct embryological origin and
phylogenetic factors.