Some modern medical books call this the pharyngotympanic tube.

The bony part of pharyngotympanic tube is about 12 mm.

Within the middle ear the simple epithelium gradually transitions into ciliated pseudostratified epithelium lining the Eustachian tube now known as the pharyngotympanic tube becoming continuous with the respiratory epithelium in the pharynx.

The pharyngeal plexus provides sensory innervation of the oropharynx and laryngopharynx from CN IX and CN X. (The nasopharynx above the pharyngotympanic tube and the torus tubarius is innervated by CN V)

The salpingopharyngeus muscle arises from the superior border of the medial cartilage of the pharyngotympanic tube (Eustachian tube), in the nasal cavity, making the posterior welt of the torus tubarius; it passes downward and blends with the posterior fasciculus of the palatopharyngeus muscle.