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The tongue (lingu, glossa) Is muscular membrane filing the mouth cavity, between body 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 = cylindrical fibrous tissue enveloping fat & muscle (located ventrally at apex in carnivores). 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 Teeth : or dentes : These tissues vary somewhat in their arrangement in the two main types of tooth. (Note: not all teeth can be classified into these types). 1-low-crowned or brachydont teeth (brachys =short +odous=tooth), which have deep roots in relation to the crown; the crown is covered in enamel, and in general the teeth stop growing once they have reached adult size. This is the kind of tooth found in man, dogs , pig and ruminants . 2-high-crowned or hypsodont teeth(hipsos=height,+odous=tooth)(overgrowing) ,the teeth having no distinct neck, which have high crowns in relation to the roots; the crown is covered in cement as well as enamel, and enamel also extends into the root. The teeth may retain the potential for growth throughout life .As the surface wears down (by about 2-3mm per year), the pulp cavity may become exposed, but this is sealed off by secondary dentine formed as result of odontoblast activity. This is the kind of tooth found in herbivores, including the horse. *Each tooth is suspended in its bony socket, the alveolus, by a dense, irregular collagenous connective tissue, the periodontal ligament. The gingival also supports the tooth, and its epithelium seals the oral cavity from the subepithelial connective tissue spaces. The portion of the tooth that is visible in the oral cavity is called the crown, whereas the region housed within the alveolus is known as the root. The portion between the crown and the root is the cervix(neck). The entire tooth is composed of three calcified substances, which enclose a soft, gelatinous connective tissue, including sensory nerves , arteries , veins , lymphatic and primitive connective tissue called the pulp , located in a continuous space subdivided into the pulp chamber and root canal. The root canal communicates with the periodontal ligament space via a small opening, the apical foramen, at the tip of each root. It is through this opening that blood and lymph vessels as well as nerves enter and leave the pulp. The mineralized structures of the tooth are enamel, dentin, and cementum. Surface of teeth – Dentine: similar to bone, is formed by odontoblasts at base of dentine layer forming the bulk of the tooth; these remain alive for life of tooth. Dentin surrounds the pulp chamber and root canal and is covered on the crown by enamel and on the root by cementum – Enamel: the hardest substance in the body, is formed of hexagonal prisms of hydroxyapatite. Formed by ameloblasts, which disintegrate after enamel is formed; thus it cannot undergo repair. It covers only the crown in low-crowned teeth and covers the crown and body in high-crowned teeth. – Cementum : similar to thin bone, contains collagen fibers “which extend into bony socket (alveolus); they form periodontal membrane which holds tooth in place . the cementum covers the root only in low-crowned teeth and covers the entire tooth in highcrowned teeth. Thus, the bulk of the hard substance of the tooth is composed of dentin, Enamel and cementum meet each other at the cervix of the tooth. The morphology of teeth: 1-free surface (tabil surface): is the cutting surface of incisors or canines. 2-vestibular surface: are the sides next to the vestibule, the vestibular surface of incisors and canines called labial surface and the vestibular surface of premolar molar called buccal surface or cheeks surface 3-inner surface (lingual surface) is contact with tongue. 4-side surface (contact): that surface which is contact with the adjacent teeth in the same jaw. The teeth in mammals have different functions in different parts of the oral cavity: 1-Incisors: are most cranial in position , which are brachydont in dogs, but hypsodont in horses, are used for cutting off pieces of food (mainly in herbivores). Normally three on each side, upper and lower. 3-Canines: are following the incisors, and used for grasping food (carnivores) and for offence. Are absent in ruminants, and most mares. An interdentally space separates canines from cheek teeth. C (Canine) = 1 pairs 3-Cheek teeth: (premolars, molars) which are more complex, may be brachydont (dog,) or hypsodont (horse), they are located on the side of jaw, therefore called also cheek teeth or buccal teeth. P (premolar) = 4 pairs. M (molar) =3 pairs. Deciduous dentition : the baby teeth (milk teeth) developing early in life, giving the young animal a functional set of teeth. They smaller and fewer in number than the permanent dentition. Permanent dentition: the second set of teeth replacing the deciduous dentition as the jaw lengthens. They must last the life of animal. Dental formula: a shorthand represented indicating the number of teeth of an animal. Duee to bilateral symmetry . Comparative: Ruminants such as cattle, sheep and goats are herbivores with a unique digestive anatomy. A prominent feature of ruminant dental anatomy is that they lack upper incisors, having instead a "dental pad Dental Formulae Deciduous 003 = 10 Permanent 313 0033 = 16 3133 Tooth Eruption Deciduous Permanent Incisors Birth - 2 weeks 18 - 48 months Premolars Birth - 1 weeks 24 - 36 months 6 - 30 months Molars In horse : The molars and premolars of the horse are known as cheek teeth. The cheek teeth slowly erupt to compensate for the constant grinding which wears away 2-3mm per year. For this reason, horses have very long teeth that are referred to as hypsodont which means "high tooth." Dental Formulae Deciduous 303 3 1 3(4) 3 = 12 Permanent = 20(21) 303 3133 This skull is from a young horse shown by the long cheek teeth. In the maxillary arcade the cheek teeth extend into the maxillary sinus. The cheek teeth do not always wear away evenly resulting in the formation of hooks and points. These hooks and points can cut into the tongue and buccal mucosa causing great discomfort to the animal. To avoid this, horses need to have their teeth ground down with a rasp periodically - a procedure called "floating. The upper first premolars of horses are known as "wolf teeth". In dog : dental formula are : Perminant:2(I3/3 C 1(O)/1(0) P3(4)/3 M3/3)=36-42 3/3)=28 In cat : dental formula are : Perminant:2(I3/3 C 1/1 P3/2 M1/1)=30 Deciduous : 2(I 3/3 C1/1 P 3/2)=22 In pig : Swine are omnivores and there is probably no other animal that is quite as focused on food. Give a pig a treat (like the animal cracker in the mouth of the little pig to the right) and they'll do almost anything. Piglets are born with "needle teeth" which are the deciduous third incisors and the Mandibular Arcade Lateral View canines.They project laterally from the gums and can injure the sow or other piglets so are often clipped off within hours of birth. In boars, the canine teeth, or tusks, grow : throughout the animal's life. The lower tusks are kept sharp by friction against the upper ones making them formidable weapons. Numerous tubercles make the occlusal surface of the molars irregular, ideal for crushing food. Maxillary Arcade Lateral View Deciduous : 2(I 3/3 C1/1 P Dental Formulae Deciduous 3 1 3 = 14 Permanent 313 3 1 4 3 = 22 3143 Tooth Eruption Deciduous Permanent Incisors Birth - 2 weeks 8 - 18 months Canines Birth 8 - 12 months Premolars 2 weeks - 8 month 12 - 16 months Molars Hyoid bone Hyoid bone is situated chiefly between the rami of the mandible, built dorsal part extend some 4 - 22 months what further caudal, it is attached to the styloid process of the petrous part of the temporal bone by the rods of cartilage, the tympanohyoid and supports the root of the tongue, the pharynx and the larynx ,it consist of many parts: 1-the basihyoid (body): is short transverse bar, compressed dorsoventrally. They basihyoid, lingual process and thyrohyoid are fused to spur or a fork with very a short handle. 2-lingual process: a project rostral medially from the basihyoid and it is embedded in the root of the tongue during life. it is compressed laterally and has a blunt pointed free end. 3-The thyrohyoid: these correspond to the great cornea of extend caudally and dorsally from the lateral parts of the basihyoid. They are compressed laterally and the caudal end has a short cartilaginous prolongation which is connected with the rostral cornu of the thyroid cartilage of the larynx. 4-The ceratohyoids (small cornu): are short rods which are directed dorsally and rostrally from either end of the body, the ventral end has a small concave facet which articulate with the basihyoid, the dorsal end articulate with stylohyoid or with epihyoid when present. 5-The stylohyoid: are much the largest parts of the bone .they are directed dorsally and caudally are connected dorsally with the base of the petrous part of the temporal bones: A-the dorsal extremity: is large and forms two angles: 1-the articulate angle is connected by a rod of cartilage (the tympanohyoid), with the styloid process of the petrous part of the temporal bone. 2-the muscular angle is thickened and rough for muscular attachment. B-the ventral extremity is small and articulate with ceratohyoid or epihyoid. 6-The epihyoid: are small, wedge shaped pieces or nodules interposed between the ceratohyoids and stylohyoids. They are usually transitory and unite with the styloids in the adult. Hyoid muscles: This is group consisting of eight muscles, one of which, the hyoideus transversus is un paired: 1-The mylohyoideus muscle: together with its fellow from a sort of sling between the molar parts of the mandible, in which the tongue is supported. Origin: the medial surface of the alveolar border of the mandible. Insertion: the lingual process, basihyoid bone and thyrohyoid bone. Action: it raises the floor of the mouth, the tongue and the hyoid bone. 2-Stylohyoideus muscle: is a slender and fusiform muscle having direction nearly parallel to that of the thyroid bone. Origin: the muscular angle of the dorsal extremity of the thyrohyoid bone. Insertion: the rostral part of thyrohyoid bone. Action: it draws the base of the tongue and the larynx dorsally and caudally. 3-The occiptohyoideus muscle: is a smaller triangular muscle, which lies in the space between the jugular process and stylohyoid bone. Origin: the jugular process of the occipital bone. Insertion: the dorsa extremity and ventral edge of the stylohyoid bone Action: it carries the ventral extremity of the thyroid bone caudally. 4-The geniohyoideus muscle: is long spindle shaped muscle, which lies under the tongue. Origin: medial surface of the molar part of the mandible close to the symphysis. Insertion: the extremity of lingual process of the hyoid bone. Action: it draws the hyoid bone and tongue rostrally. 5-The ceratohyoideus muscle: a small triangular muscle lays in the space between the thyrohyoid and ceratohyoid bones, under cover the hypoglosseus. Origin: the caudal edge of the ceratohyoid bone and ventral border of the stylohyoid bone. Insertion: the dorsal edge of the thyrohyoid bone. Action: it raises the thyrohyoid bone and the larynx. 6-The hyoideus transversus muscle: is small unpaired muscle, which extends transversely between the two ceratohyoid bones. Origin: ceratohyoid bones. Insertion: thyrohyoid bone. Action: when it contracts, it elevates the root of the tongue. 7-The sternothyrohyoideus muscle: is long, slender and digastrics muscle applied to the ventral surface of the trachea. Origin: the cartilage of manubrium. Insertion: the basihyoid bone and lingual process of the hyoid bone. Action: to retract and depress the hyoid bone, the base of tongue and the larynx. 8-The omohyoideus muscle: is thin, ribbon like. Origin: the sub scapular fascia close to the shoulder joint. Insertion: the basihyoid bone and lingual process of the hyoid bone. Action: to tact the hyoid bone and the root of the tongue. Muscles of mastication (mandibular muscle): The muscles of this group are six in number in the horse, they are extending from the maxilla and the cranium, and are all inserted into mandible. 1-The masseter muscle: it is semi-elliptical in out line. Origin: zygomatic arch and facial crest. Insertion: lateral surface of the ramus of the mandible. Action: to bring the jaws together. 2-The temporal muscle: Occupies the temporal fosse. Origin: the temporal fosse Insertion: the coroniod process of the mandible. Action: raise the mandible. 3-Pterygoidus medialis muscle: occupies the medial surface of the ramus of the mandible similar to that of the masseter laterally. Origin: the crest formed by the pterygoid process of the basisphenoid and palatine bone. Insertion: medial surface of the ramus of the mandible. Action: to raise the mandible. 4- Pterygoidus lateralis muscle: is similar than the preceding one .it is situated lateral to its dorsal part. Origin: the lateral surface of pterygoid process of the basisphenoid bone. Insertion: the mandible. Action: to draw the mandible rostrally. 5-The digastricus muscle: is composed of two fusiform flattened bellies united by round tendon. The occiptomandibular part of the caudal belly extends from jugular process of occipital bone to the caudal border of the mandible. It covered by parotid gland. Origin: jugular process of occipital bone. Insertion: medial surface of the ventral border of molar part of mandible. Action: it assists in depressing the mandible and opening mouth.