Comparative Anatomy of Digestive System 2024 PDF

Comparative anatomy of digestive system Dr Ahmed Elfayoumy 2024  Digestive system is responsible for: Break down of complex food into smaller portions, so can be utilized for energy, growth and cellular renewal So, it receive food mechanically and chemically break down it abso...

Comparative anatomy of digestive system Dr Ahmed Elfayoumy 2024  Digestive system is responsible for: Break down of complex food into smaller portions, so can be utilized for energy, growth and cellular renewal So, it receive food mechanically and chemically break down it absorbing the molecules finally eliminate non absorbed products Its shape is varied according to animal species and its feeding habits  Stage of digestion Movement of food Secretion Digestion Absorption elimination  Component of digestive system Alimentary or digestive canal is long tube from mouth to anus (oral cavity, pharynx, esophagus, stomach, small intestine, large intestine and anus Accessory glands (salivary glands, liver and pancreas  The structures and shape of digestive system is varied according to type of feed and feeding habits  Mouth (oral cavity) The oral cavity with its structures help in Prehension lip Mastication In salivation Hard palate Grooming Check Defense Communication Soft palate Thermoregulation Palatoglossal Respiration fold It extend from lips rostrally till the isthmus faucium caudally (opening between mouth tongue and pharynx  boundary of oral cavity rostrally by the lips, laterally by the cheeks, lip dorsally (roof) is the hard palate, Hard palate ventrally mandible and associated tongue. Check Caudally, the oral cavity is communicated Soft palate with the oropharynx through a narrow isthmus (isthmus faucium) that is Palatoglossal bounded by fold 1. Ventrally the root of the tongue 2. Dorsally soft palate tongue 3. Laterally palatoglossal fold  Hard palate Soft palate Mouth Tongue esophagu s Mandible Nose pharynx Larynx Tongue  Division of oral cavity In closed mouth, the oral cavity is divided by teeth and alveolar processes into oral vestibule and oral cavity proper. The two parts are communicated through inter dental space The largest is diastema (between last incisor and first premolar And space found behind the last molar teeth. diastema  Oral vestibule is divided into: 1. Labial vestibule is the space found between the incisor teeth and lips. Here, you can find the labial frenulum (mucosal fold connect lips with gum that is single on all animals except dog is double. 2. Buccal vestibule is found between the cheek teeth and the cheeks. Labial and buccal vestibules are freely communicated  Lips assist in sucking and prehension of food and may act as a tactile organ. Musclocuatneous folds surround the oral cleft oral cleft (entrance to the oral cavity) is bounded by the edges of upper (maxiilary) lip and lower (mandibular) lip, lips united on each side forming oral commissure. Central part of the upper lip presents a vertical groove known as philtrum in some species ( clear in dog, small ruminants) and (upper lips has fissure in camel), Lower lip has a rounded prominence referred to as chin or mentum that well developed in ox horse and camel Inner surface of each lip is connected with the gum by a median fold of mucous membrane known as labial frenulum that is double in carnivores Lips is well movable in camel , horse, dog and small ruminant and less movable in ox and pig  Shape and size of lips vary according to feeding habits of each animal o In horse, the lips are long and highly mobile with tactile hair o In cat, the lips are short and less mobile. In dog the lips are larger than cat and can be moved caudally but can’t be used in prehension. Dog and cat have clear philtrum and long oral cleft to expose teeth and tongue during feeding o In cat the tactile hair is long (whiskers) and has well developed sebaceous glands (circumoral glands) to clean the skin o In ox is relatively less mobile and the middle segment of upper lip fuse with skin between nostrils forming nasolabial plate (muzzle). It is insensitive with numerous opening of serous gland (its secretion is an indication of healthy animal) o Also in ox inside of the lips and near the angle of the mouth there is a numerous well developed labial papillae and directed caudally and are continued within that of the cheek. o In small ruminant the philtrumis is deep and inside surface of lip has rows of short, blunt labial papillae  o In pig the upper lip fuse with nostril forming rostral disc (rostrum) and The upper lip has a notch laterally which accommodate with the canine teeth (Tusks) o In camel the upper lips in addition to philtrum has longitudinal fissure to help feeding of sharp plants Structures of lips (skin, muscle inner mucous membrane with labial glands) Oral cleft is long in carnivores animals  Gum It is a part of oral mucous membrane that is united to alveolar process of jaws, and closely encircles the neck of teeth. In ruminants the upper incisors are absent So the gum is modified to form the dental pad, which takes the place of upper incisors  Cheeks: forms the lateral wall of oral vestibule extending from the angle of the mouth to the pterygomandibular fold that arises from the palate to the lower jaw behind the last molar. Its structures are skin, muscle buccal glands and inner mucous membrane The glands divided into Dorsal and ventral buccal glands are found between the mucous membrane and muscles of the cheeks. Inner surface is smooth except in ruminant where is rough due to cornified papillae it contains parotid papilla where the parotid duct opens at certain level differs according to animal species  Hard palate (anterior roof) it is the oral mucous membrane that is hardly attached to the oral surface of the bony separation between oral and nasal cavity (palatine bone, palatine process of maxilla and premaxilla) and is bounded laterally and cranially by the upper dental arch  Nasal cavity Hard palate Tongue cheek Oral vestibule Oral cavity proper It help in mastication so its shape is vary among species based on food and feeding habits  In all animals it has different shape nearly has Same width in horse narrow rostrally wide caudally dog Wide rostrally and caudally narrow in middle as ruminant it is divided into two symmetrical halves by a median palatine raphe either crest dog or groove horse and ruminant On either side of which, there are transversely directed palatine ridges.  incisive papilla is situated just behind the upper incisor teeth or dental bad in ruminant It contain openings of nasoincisive duct that connect the nasal and oral cavity The openings of nasoincisive duct is closed in horse and camel  Hard palate of horse: incisive papilla Shape: It has the same width along its entire length from the incisor teeth to last cheek teeth. Palatine ridges: About 16-18 in number, carved caudally and extend to the level of the soft palate. Palatine raphe: It is represented by a deep groove. Incisive papillae Oval in shape flanked by a fissure on each side, and the incisor duct is obliterated (closed) Mucous membrane is smooth Deeply contain venous plexuses Soft palate  Hard palate of ruminant wide cranially and caudally, narrow at its middle Palatine ridqes: About 15 in ox 14 in sheep and 12 in goat, the ridges do not extend caudally. Only in ox, the caudal border is serrated due to the presence of horny papilla. Palatine raphe: It appears as a prominent groove. Dental bad: Upper incisors are absent and instead the gum is modified into thick semilunar plates of connective tissue incisive papillae: Diamond in shape situated caudal to the dental pad, and is surrounded by an annular groove  Hard palate of dog Shape; It is narrow cranially and wide caudally. Palatine ridges: about 6-10 in number, concave caudally with equal intervals between them and do not extend caudally Palatine raphe: It is represented by an indistinct median crest. Incisive papilla: Four-sided, nipple-like or triangular situated behind the upper incisor tooth. Soft palate Hard palate Soft palate Mouth Tongue esophagu s Mandible  Soft palate (posterior roof) It is a movable musclomembranus fold, which extends from the caudal border of hard palate caudoventrally between the oral and nasal parts of the pharynx. Its caudal concave free end is called palatine arch which lies near the base of epiglottis Its lateral border connected Nose rostrally with root of tongue by pharynx palatoglossal folds The folds are the boundary of Tongue Larynx isthmus fuacium  The free end palatine arch Trachea extend within the wall of pharynx as palatopharyngeal Esophagus folds Esophageal The palatopharyngeal folds opening join at esophageal opening forming the palatopharyngeal Palatopharyngeal folds arch Wall of pharynx Larynx Soft palate Root of Tongue palatoglossal folds  Tonsillar fossa: lies between the palatoglossal fold and palatopharyngeal fold and contains lymphoid aggregation known as palatine tonsile Structures: oral mucosa in its oral surface Respiratory mucosa in its pharyngeal surface Middle muscular and glandular layer Size of hard palate is varied between species in horse is very long and extend to the base of epiglottis so horse can not make mouth breathing and vomiting is impossible in normal condition In camel very long and has large diverticulum termed as dolla or golla which may be considered as an organ of sexual expression in the male and is not functional in the she–camel  Muscle palatinus (palatine muscle) It extends from the caudal border of the palatine bone to the caudal border of soft palate. It shortens the soft palate. Muscle tensor veli palatini (tensor muscle of soft palate) It extends from muscular process of petrous part (temporal bone) to the aponeurosis of soft palate. It tenses the soft palate. Muscle levator veli palatini (levator muscle of soft palate) like former. but little medial It elevates soft palate toward the nasal cavity during deglutition. Muscle palatopharyngeal: It extends from palatine and pterygoid bones through palatine aponeurosis to the pharynx and larynx. It pulls the pharynx dorsally, cranially and medially shortening it during swallowing Muscles of soft palate and extrinsic muscle of tongue Tensor veli palatini Levator veli palatini Palatopharyngeal Hyoglossal Genioglossal Styloglossal