Download The tongue (lingu, glossa)

The tongue (lingu, glossa)
Is muscular membrane filing the mouth cavity, between arms of mandible, it fills the oral cavity
proper, the shape of it different according to the species of animal, it consist of:
1-the root (radix lingua): is the caudal part of tongue which attached to the hyoid bone , soft palate
and pharynx , only the dorsal part of it is free.
2-the body: Is the middle part of tongue attached to the mandible , and has three surfaces, except in
dog have two surfaces:
A-dorsal surface (dorsum).
B-lateral surface: it is flat, become round and narrow cranially.
C-ventral surface: is attached with geniohyoideus and mylohyoideus muscle.
3-the apex (toe): Is the free part which is spatula shape and have upper and lower surface and two
borders(rounded), from the lower surface of apex, there is a fold of mucous membrane fold bases to
the floor of oral cavity, form the frenulum linga.
Function of lingua:
1-main fold for the intake solid and liquid.
2-it is important tactile organ taste of food.
3 it is important in the mastication of food
swallowing.
4-can is use for cleaning the skin and hair.
Structure of tongue
1-Intrinsic muscle: they are form the substance of
tongue and they are run longitudinally, vertical and
transverse direction.
2-Lingual glands: found between the intrinsic
muscles .
3-Mucous membranous: it covers the intrinsic
muscles,
the mucous membrane of dorsal
surface have two types of papillae according to
the function:
A-Mechanical papillae:
1-Conical papillae in shape located on the caudal
third of the tongue dorsum .
2-Lenticular papillae in shape: large and wide
papillae.
3-Filliform papillae are soft or smooth horny
threats.
B-Gustatory papillae:
1-Fungiform: they are large and easy in seen,
rounded at the free end, they are found in the lateral
part of the tongue and dorsal surface.
2-Vallate papillae: are found on the caudal part of dorsum rostral to the root of the tongue. They are
circled by a cleft filled with taste buds.
3-The foliate papillae : are situated just rostral to the palatoglossal arches of he soft palate , where
they form round eminence.
Species differences :
1- torus linguae : around swelling of the caudodorsal surface of the ox tongue.
2- Lingual fossa : depression in front of the ox torus linguae. This is a site of penetration of the
foreign objects .
3- Tongue cartilage : the dog has a bar of cartilage(lyssa)embedded in the ventral surface of the
apex. The horse has a similar structure embedded in the median plane of the dorsal surface.
4- In horse the conical papillae and lenticular papillae absent , and the vallate papillae are usually
two or three in number.
5- The tunica mucosa of the tongue of ox is often pigmented and may be spotted.
6- In ox the apical half of the dorsum , rostral to the torus , is covered by filiform papillae directed
caudally , these are cornified and sharp , especially on the apex, and impart the roughness which
makes the bovine tongue an efficient organ of prehension in grazing. In the sheep and goat the
papillae are soft and the tongue is smooth ; it dose not act as a prehensile organ.
7- Lenticular papillae and conical papillae are found in the ruminant and the vallate papillae in ox
and goat 8-17 in number form an irregular double row on each side of the caudal part of the
dorsum, in sheep they number 18-24 on each side . foliate papillae absent in ruminant
Innervation of the tongue :
1-taste (special sense): the sense of the rostral two third of the tongue is carried over the chorda
tympani nerve, a branch of facial nerve .
2-taste from the caudal third of the tongue passes by the glossapharyngeal and vagus nerves.
3-sensation (pain , temperature and tactile) : carried over the lingual branch of the mandibular nerve.
4-motor innervation : by the hypoglossal nerve.
Vessels : the arteries of the tongue are the lingual and sublingual branches of the linguofacial trunk .
The veins go to the linguofacial and maxillary veins.
The lymph vessels : go chiefly to the retropharyngeal lymph nodes