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.

The stereoscopic orientation of the lumbar zygapophyseal joints and the stability triangle of the motion segments were studied on 56 sets of adult lumbosacral skeletons. The orientation of the lumbar zygapophyseal joints changed gradually from about sagittal plane in upper segment to about coronal in lower. The gravity center of the stability triangle of the motion segments moved backward from upper to ower progressively. Therefore, the stability of lumbar spine decreases and the mobility increases successively from upper downward.

The architecture of the specialized myocardial fibers of the atrioventricular junction area(AVJ) were observed under microscope on serial sections. It was found that the human A-V node extend backward divergently to form two posterior extensions (left and right, LPE, RPE). The A-V node can be divided into a superficial layer and a deep layer, and the deep layer further divided into a upper part and a lower part. The fibers in the superficial layer are vertical, and join with the lower part of the deep layer at the anterior extremity of the node. The lower part of the deep layer is the main axis of the node. The fibers in the lower part of the deep layer are longitudinal, and join with the RPE at the posterior extremity of the node. The fibers in the upper part of the deep layer are oblique and join with the LPE at the posterior extremity of the node, and mix with the lower part at the anterior extremity. The longitudinal dissociation of the anterior part of the His bundle is more distinct than that of the posterior part. The lower-left part of the bifurcating part of the bundle extend to form the posterior left branch, the upper-left and upper-middle parts of the bifurcating part extend to form the anterior left branch, and the right part and lower-middle part of the bifurcating part extend to form the right bundle branch. The morphological evidence of the dual or multiple conducting pathways, the longitudinal dissociation and the reentry pathways in the AVJ were discussed.