Configuration of the extrinsic muscles of the tongue and their spatial interrelationships.
OBJECTIVE
The tongue is a highly muscular organ, and the extrinsic muscles of the tongue overlap one another, which makes their configuration intricate. The aim was to clarify their spatial interrelationships.


METHODS
The extrinsic muscles of the tongue were gross anatomically investigated in 42 cadavers.


RESULTS
The hyoglossus consisted of two parts arising from the hyoid body and the greater horn, respectively. They ascended to the tongue external to the genioglossus. The quadrilateral anterior part contained several parallel bundles, and the triangular posterior part comprised of three bundles converging to the insertion. The genioglossus consisted of many compartments. Although its fibers radiated from the mental spine to the tongue internal to the inferior longitudinal muscle, the lateral fibers of the inferior parts passed externally to it, and the most inferior part attached to the hyoid bone and the epiglottis. The chondroglossus arising from the lesser horn ascended internally to the lateral fibers of the inferior parts. The styloglossus arising from the styloid process coursed externally and internally to the hyoglossus and between its two parts. The external and internal bundles fused with the fibers of the palatoglossus and the superior pharyngeal constrictor, respectively. Three bundles were inserted into the apex with the inferior longitudinal muscle or joined the inferior parts of the genioglossus.


CONCLUSIONS
The extrinsic muscles are subdivided into small groups of fibers depending on their spatial interrelationships, suggesting that they contain many functional units. Some units act separately, and others cooperate across the traditional boundaries of the muscles.
Basic Sciences of Oral Health Care, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan. y.sakamoto.bsoh@tmd.ac.jp.
Yujiro
Y
Sakamoto
D000368:Aged; D002102:Cadaver; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D014059:Tongue / Q000033:anatomy & histology*
Chondroglossus; Genioglossus; Human gross anatomy; Hyoglossus; Palatoglossus; Styloglossus