The cartilaginous portion (pars cartilaginea tubæ auditivæ), about 24 mm. in length, is formed of a triangular plate of elastic fibrocartilage, the apex of which is attached to the margin of the medial end of the osseous portion of the tube, while its base lies directly under the mucous membrane of the nasal part of the pharynx, where it forms an elevation, the torus tubarius or cushion, behind the pharyngeal orifice of the tube.
The upper edge of the cartilage is curled upon itself, being bent laterally so as to present on transverse section the appearance of a hook; a groove or furrow is thus produced, which is open below and laterally, and this part of the canal is completed by fibrous membrane.
The continuous lower edges of the cartilage are divide into a lateral and a medial lamina.
The cartilage lies in a groove between the petrous part of the temporal and the great wing of the sphenoid; this groove ends opposite the middle of the medial pterygoid plate.
The cartilaginous and bony portions of the tube are not in the same plane, the former inclining downward a little more than the latter.