2012 年 10 巻 4 号 p. 318-329
Clarification regarding the presence of muscle spindles (MS) in the lateral pterygoid muscle (LPM) is important for understanding jaw function. Animal studies to date have revealed inconsistent findings and little research has been conducted on human LPM specimens. In the present study, LPM specimens from two adult human donors were investigated to determine the presence of MS. After fixation, specimens were separated into superior and inferior head sections and embedded in paraffin. Slices of 12 and 8 μm were prepared and every 10th slice was stained with hematoxylin-eosin. Slides were observed consecutively under an optical microscope in order to view entire spindles. Muscle spindle markers comprised distinct spindle capsules and sites thought to be intrafusal muscle fibers within the muscle. Immunostaining with anti-S-100 antibodies in the equatorial region was also performed to identify MS. In specimens from both donors, multiple MS covered by connective tissue were observed in the inferior head of the LPM, and on immunostaining, muscle spindle nerve endings were observed extending into the equatorial region. These results confirm the presence of MS in the inferior head of the LPM.
