Mechanical contraction property of the levator veli palatini muscle

The Behaviors of the Levator Veli Palatine Muscle Between 2 Surgical Conditions in Dog: The Comparison of Furlow and Pushback Methods

OBJECTIVE

This study was conducted to compare the velopharyngeal function among the beagle dogs which the levator veli palatini (LVP) muscles construction has been experimentally changed.

METHODS

Four groups of LVP muscle reconstruction were made (normal LVP, cut LVP, end-to-end sutured LVP, and overlapped-sutured LVP at the midline). Levator veli palatini contraction was induced by electrical stimulation or a hypercapnia condition to analyze the strength of the velopharyngeal closure using balloon with a blood pressure meter, and the electromyogram in those operated beagle dogs.

RESULTS

Under a hypercapnia condition, the velopharyngeal function did not differ significantly among the 4 groups in the terms of velopharyngeal pressure. The strongest closure was shown at the overlapped sutured LVP group by electrical stimulation.

CONCLUSION

The reconstruction of overlapped sutured LVP showed the most effective closure. This study suggested that the palatoplasty should be conducted along the overlapped LVP (like Furlow method).

Contraction properties of the superior pharyngeal constrictor muscle

OBJECTIVE

The mechanical contraction property of the superior pharyngeal constrictor (PC) muscle was analyzed and compared with the levator veli palatini (LVP) muscle.

DESIGN

Twenty adult dogs anesthetized with sodium pentobarbital were used.

RESULTS

The isometric contraction curves of LVP and PC were recorded after direct electric stimulation to each muscle. The contraction time of isometric twitch contraction of the superior PC muscles was 30.3+/-5.25 msec, and the half relaxation time was 22.97+/-5.44 msec. The summation curve was observed at a stimulus frequency above 20 Hz of a repetitive pulse stimulus frequency of 85 Hz.

CONCLUSIONS

The mechanical contraction properties of the PC muscle are similar to those of the LVP, but with more aspects that are characteristic of a fast twitch muscle.