Circumvallate papillae

The circumvallate papillae (or vallate papillae) are of large size (dome-shaped structures), and vary from eight to twelve in number.

They are situated on the dorsum of the tongue immediately in front of the foramen cecum and sulcus terminalis, forming a row on either side; the two rows run backward and medially, and meet in the midline, like the limbs of the letter V inverted.

Each papilla consists of a projection of mucous membrane from 1 to 2 mm. wide, attached to the bottom of a circular depression of the mucous membrane (some text referred to as moats); the margin of the depression is elevated to form a wall (vallum), and between this and the papilla is a circular sulcus termed the fossa.

The papilla is shaped like a truncated cone, the smaller end being directed downward and attached to the tongue, the broader part or base projecting a little above the surface of the tongue and being studded with numerous small secondary papillæ and covered by stratified squamous epithelium.

Ducts of lingual salivary glands, referred to as Von Ebner's glands empty serous secretion into the base of the circular depression (moats). The function of the secretion is presumed to flush materials from the base of circular depression to ensure that taste buds can respond to changing stimuli rapidly. (Michael H. Ross, Histology: A text and alas 5th edition)

The circumvallate papillae get SVA innervation from cranial nerve IX, the glossopharyngeal nerve, even though they are anterior to the sulcus terminalis. The rest of the anterior 2/3s of the tongue gets SVA innervation from the chorda tympani of cranial nerve VII, distributed with the lingual nerve of cranial nerve V.