[Histological observations on structure of endomysium, perimysium and epimysium of lateral pterygoid muscle in rat].

To understand the muscle as a locomotorium, I observed the structure of the connective tissue sheaths (the endomysium, the perimysium and the epimysium) in the mature rat lateral pterygoid muscle. The following results were obtained using the macroscopy and light and electron microscopy. The lateral pterygoid muscle consists of two parts. The superior head originates from the basisphenoid and is mainly inserted into the articular disk and capsule. The inferior head originates from the lateral pterygoid processus and is mainly inserted into the condylar processus of the mandible. The perimysium is thick and bound the fasciculus secondarily as sheaths near the insertion of the superior head. The collagenous fibers are very fine in the endomysium. The collagenous fibers that make the connective tissue sheaths arrange on a skew against the muscle fibers, but parallel around the origin and the insertion. It seems that the connective tissue sheaths in the rat lateral pterygoid muscle, in view of the morphology, retain the forms of fasciculus, act as the runways for the muscle fibers in time of expansion and contraction and offer spaces for the attachment of the muscle fibers.