The intrinsic muscles of tongue are those muscular structures which form and constitute this organ of speech. They are inherent to the tongue proper, giving it shape. In other words, they give it the very well-known elongated, muscular consistency that we know, playing a key role in the articulation of human speech, especially in the pronunciation of consonant letters. The intrinsic muscles of tongue are four. From top to bottom, they are:
1) the superior longitudinal muscle of tongue, which travels from base to tip along the top of the organ with long fibers. Function: it bends the tongue, curling its tip backwards;
2) the inferior longitudinal muscle of tongue, which is long and narrow, lying in the tongue lateral of genioglussus muscle.
3) the transverse muscle of tongue (transversus linguae), which is made up of separate transverse muscle fibers, originating from the septum of tongue. Function: it raises the lateral aspects of tongue, making it convex, like a trough;
4) the vertical muscle, which is made up of short fibers lying between the dorsum and the inferior surface, with its function being flattening the tongue.
Action
The superior longitudinal muscle retracts the tongue and curls up its tip, while the transverse curls up the sides of this organ. The inferior longitudinal collaborates with the superior longitudinal muscle to draw back the tongue, making it thick. The vertical muscle flattens this organ sideways.
Nerve supply
They are innervated by a branch of the glossopharyngeal nerve (CN IX), which transmits sensory information, and by the hypoglossal nerve (CN XII), which supplies with motor innervation.
Blood supply
The intrinsic muscles of tongue are supplied by the deep lingual artery, which branches off the lingual artery, and this, from the external carotid artery.
Down below, inferior view of human tongue, showing the extrinsic muscles and only two of the intrinsic muscles of tongue: the inferior longitudinal and the transverse muscle.
