Tongue

1. Tongue The tongue isfleshy, movable, muscular organ, attached in most vertebrates to the floor of the mouth, that is the principal organ of taste, an aid in chewing and swallowing, and, in humans, an important organ of speech.

2. Regions of tongue • Blade: The blade is the region of the tongue anterior to the frenulum. • Body: The body extends from the circumvallate papillae to the frenulum, the anterior part of the genioglossus muscle. The body is the largest segment and it convenient to arbitrarily separate the body into an anterior and posterior part. The anterior body is beneath the hard palate, the posterior body lies beneath the soft palate. • Base or root : The base, or root, is that part of the tongue posterior to the sulcus terminalis, the line of circumvallate papillae taste receptors.

3. Anatomically ,the tongue formed of two main regions: • Lingual mucosa. • Lingual muscles. Lingual muscles divided into two main groups: • Extrinsic muscle: The extrinsic muscles have one attachment to a bone (mandible, hyoid bone or styloid process) while the other end inserts within the tongue. • Intrinsic muscles : Intrinsic muscle originate and insert within the tongue and have no bony attachments.

4. Orientation of tongue muscle: • One set runs parallel to the screen from upper left to lower righ. • A second set runs at a right angle to these from lower left to upper right. • The third group is cut in cross section, as it runs in and out of the plane of the screen; it's therefore at right angles to both the other two.

5. Lingual papillae Filiform Papillae: • Are numerous .  • Slender conical structures, project upwards forming a velvety covering on the tongue. • its function is purely mechanical. • In cattle ,they are extremely large and rough. • The stiff papillae make effective bristles for removing debris. • In large animals, such as cows, the filiform papillae reached up to perhaps 5.0 mm long.

6. GustatoryPapillae • Fungiform papillae: Are less common than the filiforms. • Vallate (or circumvallate) : The largest and most prominent, • Foliate papillae: which are most easily seen in the Order Lagomorpha (rabbits, hares, and conies).

7. Fungiform papillae: • Are mushroom shaped structures.  • Rise above the general level of the filiform papillae, and have taste buds. • Carry taste buds. • Are less numerous than the filiform type, and scattered in among them. • Are large enough to have a core of connective tissue. • The papillae are flat-topped and have deep clefts between them. • The clefts are lined with epithelium, and contain taste buds embedded in them.

8. Foliate papillae: • Is best seen in rabbits and is "leaflike" . • Set in the sides of the tongue. • Rise above the general level of the filiform papillae, and have taste buds. • Carry taste buds. • Are less numerous than the filiform type, and scattered in among them. • Are large enough to have a core of connective tissue. • The papillae are flat-topped and have deep clefts between them. • The clefts are lined with epithelium, and contain taste buds embedded in them.

9. Vallate Papillae • Is set into a deep pocket in the tongue's surface. • It doesn't protrude above the general level of the surface. • Are easily visible with the naked eye in most animals. • They're paired and located near the back of the tongue. • They're the least numerous type. • This very large structure has a core of connective tissue (CT). • Taste buds (TB) are present on the sides of the papilla. • The small lingual salivary glands (SG) that empty into the moat keep the taste buds ready for re-use. • There are two types of these lingual salivary glands: serous and mucous in nature. The secretions of these glands are wash the chemoreceptor sites of the taste buds free of molecules, so that new sensations can be detected.