The superior longitudinal muscle of tongue is one of the four intrinsic muscles which form this muscular organ of the oral cavity. It underlies the superficial mucous membrane and submucous fibrous layer of the tongue. It is made up of a thin layer of oblique and longitudinal muscular fibers. It is also known as superior lingualis in older text books.
Origin and Insertion
The superior longitudinal muscle of tongue arises from the lesser horns of the hyoid bone, by two lateral slips, and from the anterior surface of epiglottis by a medial slip. Then these three slips converge and pass immediately under the mucous membrane, running along the whole dorsum of the tongue to its tip, interlacing with one another.
The oblique muscular fibers, which constitute the superior longitudinal muscle, runs forward obliquely and laterally to the edges of the tongue. Meanwhile, its longitudinal fibers runs straight forwards to the tip of tongue. Both types of fibers insert themselves in between the extrinsic muscular fiber ends of the styloglossus, palatoglossus, hyoglossus, and chondroglossus muscles, which constitute the base of the tongue.
Innervation and Blood Supply
The superior longitudinal muscle of tongue is innervated by the hypoglossal nerve (CN XII) and is supplied by a branch of the lingual artery.
Action
This longitudinal lingual muscle raises the tip of tongue, curls it backwards, and shorten it, making it thicker. Thus, it is important when it comes to speech, because we use it when we pronounce some consonant letters.
Down below, the human tongue, showing the superior longitudinal muscle (superior lingualis). The surface of tongue (superficial mucous membrane and the submucous fibrous) layer have been removed to expose it.