Morphology of the tongue muscles of the mouse with special reference to the genioglossus muscle.

The mouse tongue musculature and its movements were studied macroscopically. The attachment of the extrinsic tongue muscles was also ascertained by dissection and light microscopy. 1. The genioglossus muscle of the mouse was attached to the posterior surface of the midsagittal region of the mandibular symphysis but medial and posterior to the geniohyoid tendon. 2. The genioglossus muscle was divided into three parts. Its anterior border was not straight and did not coincide with that of the intermolar eminence. This means that as in animals without an intermolar eminence, the anterior border of the genioglossus does not always coincide with an intermolar eminence. 3. On closing or opening of the mouth, the tongue shape changed in the dorsum linguae, showing an intimate relationship with the genioglossus muscle, but the position of the geniohyoid muscle remained almost static.