eRadiograph Volume 7: Imaging of Oral Cavity | Page 9

are seen clinically as 8-12 eminences on tongue surface, forming an inverted V. It is
important to differentiate the oral tongue from the pharyngeal tongue as neoplasms
arising from these regions behave differently. The oral tongue neoplasms are well
differentiated and less aggressive than those of pharyngeal tongue. The epithelium of
the anterior tongue arises from the ectoderm and is thus less aggressive, the
epithelium of pharyngeal tongue arises from the endoderm and is more aggressive.

The bulk of the tongue consists of intrinsic muscles wrapped in a mucous membrane.
There are four groups of intrinsic muscles which interdigitate - superior and
inferior longitudinal, transverse and vertical. Their principle function is to alter
the shape of the tongue by lengthening it, shortening it, flattening or rounding its
surface, curling and uncurling its apex. These changes in shape of tongue are required
for speech, swallowing and mastication. Various consonants are produced based on
the shape of the tongue. These intrinsic muscles are not visualized on CT but maybe
seen on MRI on T1 weighted images as hypointense bands interspersed amongst
hyperintense background fat. The fibrous skeleton of the tongue consists of
hypoglossal membrane and lingual septum. The hypoglossal membrane is a small but
strong fibrous lamina that connects the upper surface of the tongue to upper surface
of hyoid bone. The lingual septum divides the tongue into two symmetric halves
inserting on the hypoglossal membrane along its entire length. There are 4 extrinsic
muscles, which are attached to the hyoid bone, mandible and styloid process. The
extrinsic muscles stabilise the tongue, alter the position and shape of the tongue.
However, the importance of the extrinsic muscles is that through their point of bony
attachment they may act as a conduit for spread of disease to adjacent structures,
upstaging the tumor to T4A.
Genioglossus - This forms the bulk of tongue. This is a fan shaped paired muscle,
arising by its apex from superior genial tubercle behind mandibular symphysis,
radiating posteriorly to the whole dorsum of the tongue from base to apex. These lie

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Imaging of Oral Cavity

The oral tongue contains more fat than the pharyngeal tongue - this makes it easier to
detect neoplasm in the oral tongue as compared to the pharyngeal tongue. The
musculature and internal contents of oral and pharyngeal tongue is similar. The oral
tongue is considered as a part of the oral cavity and the pharyngeal tongue is
considered as a part of the oropharynx. On axial images, the anterior tongue is
separated from the posterior tongue by a line connecting the anterior aspects of the
mandibular ramii. The tongue has an apex, inferior surface, dorsum, free lateral
surfaces and root, which is attached to the hyoid bone. The valleculae are considered a
part of the tongue. These are small mucosal strips that form a transition between
tongue base and the epiglottis. The oral tongue is also referred to as the mobile tongue
and the root of the tongue. The pharyngeal tongue, which forms the anterior wall of
the oropharynx, is also referred to as the base of the tongue.