Insertion of the tensor veli palatini muscle into the eustachian tube cartilage in cleft palate cases.

Differences in insertion of the tensor veli palatini muscle (TVPM) into the lateral lamina of the eustachian tube (ET) cartilage between cleft palate (CP) cases and controls were investigated histologically. Thirty temporal bones with entire ETs were studied: 10 from individuals with CP and 20 controls. The ratio of the length of the ET cartilage with insertion of the TVPM to its total length from the nasopharyngeal end to near the tubal isthmus was calculated in all 30 cases. In all 20 controls, but in only 6 of 10 CP cases, the TVPM inserted into the lateral lamina of the ET cartilage at its tip portion (chi 2 test, p less than .025). The ratio was significantly smaller in CP cases (0.178 +/- 0.172) than in controls (0.419 +/- 0.120) (t = 4.305, p less than .001). We believe that abnormal insertion of the TVPM into the ET cartilage is one of the causes of the functional obstruction of the ET that contributes to the frequent bouts of otitis media experienced by those with cleft palate.