Comparative Anatomy of Digestive System PDF

Comparative anatomy of digestive system Dr Ahmed Elfayoumy 2024  Tongue is a very mobile muscular organ Have several functions; Root prehension of food intake of liquid in others suckling newborn Body helps...

Comparative anatomy of digestive system Dr Ahmed Elfayoumy 2024  Tongue is a very mobile muscular organ Have several functions; Root prehension of food intake of liquid in others suckling newborn Body helps in mastication and also acts as a tactile organ (taste bud) Lingual Apex for the cleaning of the skin fernulum Thermoregulatory  Gross anatomy of tongue It divided into 1. Root caudal attached short part Attached to hyoid bone, Root Soft palate by palatoglosal fold To epiglottis by glossoepiglottic fold 2. Middle body is the main longest part, from Body frenulum till the beginning of palatoglossal fold It have 4 surfaces Ventral , attached ventrally to oral floor by frenulum Apex Lingual linguae fernulum 2 lateral surfaces is wide in horse, ox and pig The dorsal surface is free and known as dorsum linguae  The dorsum In ruminant divided by transverse lingual fossa into Flat rostral part Raised caudal part known as lingual torus In dog the dorsum have longitudinal median groove In dog the ventral part of tongue contain median fibrous body extend from apex to root Lyssa 3- Tip or apex of the tongue is the free part of the tongue, which may be pointed, rounded or flattened in shape Tongue of dog  Fixation of the tongue 1. Bony fixation: Lingual process of hyoid bone. 2. Mucous membrane fixation: 1. Lingual frenulum to the floor of mouth cavity. 2. Palatoglossal fold to the soft palate, 3. Glossoepiqlottic fold to the base of epiglottis. 3. Muscular fixation: 1. lingual extrinsic muscles, which originate from the skeleton and enter the tongue (move the tongue) and blend with intrinsic muscle fibers 2. intrinsic muscles fibers form the main bulk structure of tongue and when contracted change the shape of tongue and not attached to skeleton  Tensor veli palatini Levator veli palatini Palatopharyngeal lingual extrinsic muscles Genioglossal M Hyoglossal Genioglossal Styloglossal Styloglossal M Hyoglossal M  Structures of tongue Muscles Mucous membranes with papillae Connective tissue Blood and lymphatic vessels and nerves Papillae of the tongue (Lingual papillae) The lingual papillae are projections of the corium layer of the lingual epithelium. According to their physiological role, it divided into mechanical gustatory papillae (with taste bud).  Mechanical papillae Gustatory papillae have no taste bud Have taste bud - Filiform P in all - Fungiform P - Conical P ruminant and camel -Vallate (circumvallate) p - Lentiform (lenticular) P ruminant and camel -Foliate P (absent in dog and ruminants) Filiform papillae: In ox :on the dorsum of the body and apex In equine, goat, dog and pig, they cover the whole dorsum as thin, soft horny threads giving it a velvety appearance. In pig and dog only, they are long soft villous like at the root  Lentiform and conical papillae: Large broad and horny located at lingual torus of ruminants and camel Gustatory papillae fungiform papillae: at lateral surfaces dorsum and apex of the tongue (mushroom in shape or rounded free end, constricted neck and a stalk) Circumvallate papillae: Situated on either side of the dorsum at the junction of the body with the root. Its shape looks like mushroom surrounded by circular groove its number is vary Horse: 1-2, Ox: 8-17, Sheep: 18-24, Goat: 12-18 camel: 8-10 Pig: 1 Dog: 2 (3) Foliate papillae: - Located on either side of the root of the tongue in front of the palatoglossal foids. in horse, they are 2-3 cm in length, while in pig is 7-8 cm in length ruminant  Tongue of dog Apex is wide, flat and spoon like with sharp border. Dorsal surface has a shallow median groove that divides the tongue into two symmetrical halves. Filiform papillae are soft villus like increase in size toward the root of the tongue.  Funqiform papillae are situated over the dorsum cranial 2/3. Circumvallate papilla are' 2-3 papillae cranial to the tongue root. Foliate papillae are not distinct. Lyssa is a median spindle like cord lies along the ventral surface of the apex consisting of a connective tissue sheath that envelops fat and islets of cartilage and muscle fiber.  tongue of the horse: Apex is broad, long and dorsoventrally flattened with rounded border (spatula in shape). Body has high lateral surfaces. Dorsal surface is velvety in texture due to the presence of fine filliform papillae. Fungiform papillae are scattered over the dorsal surface of the apex and lateral surfaces of the body. Circumvallate papillae comprise one pairs only. Foliate papillae are located on the lateral border of the tongue just cranial to palatoglossal fold forming a rounded eminence about 2-3 cm in length.  Tongue of the ruminants: Apex is pointed, body has a high lateral surface. Dorsal surface presents an oval prominence, on the caudal part of the body, called lingual torus linguae, which is limited cranially by fossa linguae. Filiform papillae are present on the dorsal surface cranial to fossa linguae, and are pointed threads, directed caudally making the surface like rasp. Fungiform papillae: located along the edges of the apex  Circumvallate papillae: about 8-17 on either side of median plane in ox, 18-24 in sheep and 12-18 in goat. Foliate papillae: absent. Conical and lenticular papillae on lingual torus help in grinding of food  Sublingual floor It is crescent in shape and consists of a cranial prefrenular part and Root two lateral sublingual recesses, which extend caudally between the mandible and lateral surfaces of tongue. Body Lingual frenulum  Prefrenular part lies inside the dental arch of incisor teeth contain sublinqual caruncle on which the ducts of mandibular and monostomatic sublingual salivary glands open Lateral sublingual recesses are bounded laterally by alvelolar cheek teeth and medially by lateral surface of the tongue. contain the polystomatic sublingual salivary gland and its openings  Salivary glands In mammals, they are exocrine glands that produce saliva into the oral cavity through their excretory ducts. According to their size and way of excretion, they are 2 types: minor (labial, palatine, buccal and lingual) major salivary glands ( parotid, mandibular and sublingual)  Minor salivary glands: This are glandular tissue within the wall of lips, palate and cheek These glands keep oral cavity moist and slippery (cleaning glands). Their excretory ducts open directly into the oral cavity. 1.Labial salivary gland (in the lips) 2. Palatine salivary gland (in the palate). 3. Lingual salivary gland (in the tongue). 4.Buccal salivary gland (in the cheek) Buccal glands are the largest one of this group and is seen by eye. In equine , they are dorsal and ventral groups, In ruminants and canines dorsal, ventral and middle group (caudal dorsal glands in dog aggregate for zygomatic gland  Major salivary glands Parotid salivary gland. Mandibular salivary gland. Sublingual salivary gland, which is divided into 2 types: monostomatic have one duct open in the sublingual caruncle polystomatic sublingual gland have several openings open directly into sublingual recess Parotid salivary glands: Is serous gland , watery secretion, and its lobule is visible by naked eye Position: It is situated in the retromandibular space between the head and neck Shape: Dog; triangular in shape its apex directed ventrally and smaller than mandibular ox: wedge shape with thick dorsal end, also smaller than mandibular gland Horse: is the largest, rectangular in shape with ventral cervical and mandibular angle  The ducts of lobules collected form parotid duct Parotid duct: In all species opens into a small parotid papilla of cheek into buccal vestibule. In dog, camel and small ruminants, the duct crosses the masseter muscle and open into parotid papilla at upper 3rd cheek tooth in dog, goat and camel and at 4th cheek tooth in sheep In horse, ox and pig, the duct runs at first on the medial aspect of the mandible, and winds around the vascular notch of mandible to gain the lateral surface of the face. It then passes craniodorsally on the cheeks to ends on lateral wall of buccal vestibule on the parotid papilla at the level of Upper 4th cheek tooth in horse upper 5th cheek tooth in ox and pig  Mandibular salivary gland Mandibular (submaxillary) gland produces a mixed serous and mucous secretion. Position: it occupies the space between the basihyoid bone and wing of atlas, and is partly covered by the parotid gland The duct of mandibular salivary gland passes rostrally to prefrenular part of sublingual space where it opens on the sublingual caruncle  In dog: oval and larger than parotid In ox: long, narrow and curved with large rounded ventral end, it is larger than the parotid gland In horse: long, narrow and curved with large rounded dorsal end. It is smaller than parotid gland  Sublingual salivary glands Present in the lateral recess of the sublingual space Mainly mucous in nature Divided into Monostomatic have one duct open into sublingual caruncle with mandibular (absent in horse and camel) Polystomatic several lobules that have several small ducts open directly into the sublingual recess (present in all)  Pharynx It is a funnel shaped musclomembranous tube connects the oral cavity with esophagus and nasal cavity with larynx. Nose pharynx Larynx Tongue  Division of pharynx 1. Cranial part re-divided by soft palate into Dorsal nasopharynx Ventral oropharynx Hard palate Soft palate 2. Caudal part (laryngeopharynx is Mouth the common part of digestive and Tongue esophagu respiratory system) s Mandible Opening of the Pharynx: 1. Paired choanae (posterior naris), nasal cavity to nasopharynx 2. Paired pharynqeal openings of auditory tubes connect nasopharynx with auditory tube of the middle ear. 3. Isthmus faucium (aditus pharyngeus) leads from the oral cavity to oropharynx. It is bounded dorsally by the soft palate, ventrally by root of tongue and laterally by palatoglossal folds. 4. Aditus laryngeus (opening of larynx): connects the pharynx with the larynx. 5. Esophageal opening: connect pharynx with esophgus  Guttural pouch (Diverticulum of auditory tube) it is the projection of the mucous membrane of the auditory tube which extending from the base of the skull to the wall of the pharynx in caudoventral direction and continuous caudally under the wing of the atlas. Filled with air This organ present in equine only and have thermoregulatory function to brain Usually inflamed and filled with pus