The Posterior tongue, or pharyngeal part, is the part of the tongue

Tongue

The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...

 behind the terminal sulcus

Terminal sulcus (tongue)

The dorsum of the tongue is convex and marked by a median sulcus, which divides it into symmetrical halves; this sulcus ends about 2.5 cm. from the root of the organ, in a depression called the foramen cecum, from which a shallow groove, the terminal sulcus, runs laterally and forward on either...

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At its root, it is directed backward, and connected with the hyoid bone

Hyoid bone

The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...

 by the Hyoglossi and Genioglossi muscles and the hyoglossal membrane

Hyoglossal membrane

The hyoglossal membrane is a strong fibrous lamina, which connects the under surface of the root of the tongue to the body of the hyoid bone.This membrane receives, in front, some of the fibers of the Genioglossi....

; with the epiglottis

Epiglottis

The epiglottis is a flap that is made of elastic cartilage tissue covered with a mucous membrane, attached to the entrance of the larynx. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally. The term, like tonsils, is often incorrectly used to refer to the uvula...

 by three folds (glossoepiglottic) of mucous membrane; with the soft palate

Soft palate

The soft palate is the soft tissue constituting the back of the roof of the mouth. The soft palate is distinguished from the hard palate at the front of the mouth in that it does not contain bone....

 by the glossopalatine arches; and with the pharynx

Pharynx

The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...

 by the Constrictores pharyngis superiores and the mucous membrane

Mucous membrane

The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

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It is derived primarily from the third pharyngeal arch. (The second arch has a substantial contribution during fetal development, but this later atrophies. The fourth arch may also contribute, depending upon how the boundaries of the tongue are defined.)