The posterior tongue, or the pharyngeal part, is the base of the tongue that is located farthest back in the mouth, close to the opening of the throat. A tongue is usually divided into two sections: the part of the tongue that is able to move is named the anterior tongue and the immobile base is called the posterior tongue. It is linked to four other anatomical structures, the pharynx, the glossopalatine arches, the hyoid bone, and the epiglottis.
A center line visible on the surface of the tongue is called the medial sulcus. It divides the tongue into equal halves. At the posterior end of the tongue towards the back of the throat, the medial sulcus runs into the terminal sulcus, which is where the posterior tongue anatomically begins. The grooved line of the terminal sulcus continues along both sides laterally until the outer edges of the tongue are reached.
One muscle in the pharynx, called the constrictores pharyngis superiores, connects it to the posterior section of the tongue. The pharynx is the part of the throat that is located immediately behind the nasal cavity and mouth. Both glossopalatine arches located on the sides of the mouth join the base of the tongue to the soft palate at the back of the roof of the mouth.
Part of the posterior tongue is attached to the hyoid bone in the throat by two muscles called the hyoglossi and genioglossi. A strong fibrous tissue called the hyoglossal membrane extends from the root of the tongue to the hyoid bone. Connecting the two structures assists in the development of vocal sounds.
The epiglottis, a small piece of elastic cartilage that is covered with a mucus membrane, is also connected to the posterior base of the tongue. Primarily, the purpose of the epiglottis is to prevent food from entering the trachea and to protect the entrance to the vocal folds. It is also part of the voice box, which has nine parts made of cartilage. Three folds of mucus membranes, called the glossoepiglottic folds, join the base of the tongue to the epiglottis.
A congenital condition that impairs an infant’s ability to breastfeed or bottle feed is called a posterior tongue-tie. It is often difficult to diagnose because the tongue-tie is not easily visible during an examination. The pediatrician may need to perform a digital exam, placing his finger inside the baby’s mouth and feeling for the improperly attached frenulum.
An infant with a posterior tongue-tie is often fussy during feedings. The baby may arch away or want to nurse again soon after the last feeding. A tremor may be visible in the baby’s jaw or tongue after the effort of suckling ineffectively. Treatment of the posterior tongue-tie is called a frenectomy. The surgeon will make a small snip into the thick short frenulum connected to the posterior tongue, allowing the infant’s tongue to move freely.