ELECTROMYOGRAPHIC STUDY OF THE LATERAL PTERYGOID MUSCLE / 解剖学报

ABSTRACT

The electromyography of the superior and inferior heads of lateral pterygoid muscle of 15 human subjects were recorded. It has been observed that marked active potential occurred in the superior head of the ipsilateral pterygoid muscle and the inferior head of the contralateral muscle during a one-side molar bite. Marked active Potential appeared in the superior head of the lateral pterygoid muscle during the closing movement of the jaw, whereas it appeared in the inferior head during the opening movement.It has not been confirmed that the lateral pterygoid muscle is an important protractor of the mandible, as only relatively weak active potential was recorded in the two heads of the muscles on both sides during the protraction of the jaw. Very marked active potential has been observed in the ipsilateral prenygoid muscle during the lateral movement of the mandible, while in the contralatenal superior head it occurred only slightly. The. above finding does not correspond to the descriptions found in current text-books.The two heads of the lateral pterygoid can therefonose considered as two functionally and structurally distinct muscles.