Veterinary Respiratory System PDF

Instructor : Dr. Abdulhafeed S. Dalab PhD in Anatomy and Cell Biology Department of Veterinary Medicine Faculty of Agriculture and Veterinary Medicine June, 2021 Outline 1  Introduction to Respiratory System Division of Respiratory System Nose Nasal Cavity Larynx Thoracic Cavity Lungs Comparative a...

Instructor : Dr. Abdulhafeed S. Dalab PhD in Anatomy and Cell Biology Department of Veterinary Medicine Faculty of Agriculture and Veterinary Medicine June, 2021 Outline 1  Introduction to Respiratory System Division of Respiratory System Nose Nasal Cavity Larynx Thoracic Cavity Lungs Comparative anatomy of Respiratory System 3/7/2024 3/7/2024 2 Introduction to Respiratory System   Respiratory system : is the connected structures from the nostrils and the nasal cavity to the lung.  Function of Respiratory System :  Assistance in regulation of gas exchange between air and blood, control of PH of body fluid and temperature  Nose (olfacation-olfactory receptors ): Environmental information (orientation and protection).  Nasal cavity and conchae : warm and moisten the air and filter foreign material.  The larynx: protects the entrance to the trachea, regulates the inspiration and expiration of air and plays major role in vocalization ( phonation) 3/7/2024 3 Introduction to Respiratory System  The respiratory System can be divided functionally into the following organs:  The respiratory passages comprise the following organs :         Sites of gaseous exchange within the lungs are:     3/7/2024 External Nose Nasal Cavity Nasopharynx Larynx Trachea Bronchi Lungs Respiratory Bronchiole Alveolar Ducts Alveolar Sacs Alveoli 4 Introduction to Respiratory System  The respiratory System can be subdivided according to organ location (cranial end of larynx) as following:  Upper Respiratory Tract:  The respiratory organs located within the head  nose, paranasal sinuses, nasopharynx  Lower Respiratory Tract:  consists of the larynx, the trachea and the lungs. 3/7/2024 5  Upper Respiratory Tract 3/7/2024 6 The Nose   The nose consist of: 1. The external narse (nostrils) and their associated nasal cartilages. 2. The nasal cavity with nasal meatus and conchae. 3. The paranasal sinuses. 3/7/2024 7 The Nose   The nose is formed by: – – – – 3/7/2024 dorsally : the nasal bones (2). ventrally : the palatine processes of the incisive bones (1), the maxillary (3) and the palatine bones (6) laterally : the maxillae (3). Caudally it is limited by the cribriform plate of the ethmoid bone. 8 Apex of the nose   The apex of the nose and the rostral portion of the mandible and maxilla form the muzzle.  The form and size of the muzzle and the nature of the integument show considerable species differences.  The integument around the nostrils is hairless and sharply demarcated from the unmodified skin in all domestic mammals. 3/7/2024 9   In the ox the integument of the rostral region is modified to form the smooth hairless nasolabial plate. 3/7/2024 10    Philtum is deep in carnivores and small ruminant (nasal plate) and shallow or absent in the pig , ox and hose.  In pig: the disc-like movable point of muzzle is called rostrum supported by rostral bone and covered by modified skin which form ( rostral plate) 3/7/2024 12 Nasal plate   Nasal plate is kept moist in cattle, pigs and dogs  In cattle and pigs : the moisture is derived from closely packed underlying glands.  In dogs: it is an overflow of the secretion of glands of the nasal mucosa called the lateral nasal glands 3/7/2024 13 Nasal cartilages   The external nares are supported by the nasal cartilages, which are variable in form, size and number depending on the species.  The lateral nasal cartilages are attached to the rostral end of the nasal septum from which they extend ventrally and dorsally.  They determine the form of the opening of the nostril.  The dorsal and ventral lateral nasal cartilages are in contact with each other in all domestic species except the horse. 3/7/2024 14  Depending on the species several accessory nasal cartilages may arise from the lateral nasal cartilages 3/7/2024 15 Nasal cartilages   In the horse: the dorsal nasal cartilage does not project far and the ventral nasal cartilage is either indistinct or absent.  this will lead to very mobile lateral walls of the nostrils and allow the opening to be dilated when necessary.  Instead, the alar cartilage, which are divided into plate (dorsally) and horn (ventrally). 3/7/2024 16 Alar Cartilage   the alar cartilage account for the a comma shape, which divides the nostril :  Ventrally to true nostril leading to the nasal cavity.  Dorsally to false nostril leading to a skin-lined diverticulum ( blind cutaneous pouch). Occupying the nasoincisive notch. 3/7/2024 17  3/7/2024 18 Nasal cartilages  3/7/2024 Horse Ox 19 Nasal cavities   The nasal cavity: is the facial portion of the respiratory tract extends from the nostrils (cranially) to the cribriform plate of the ethmoid bone and caudal nares and which is divided by the median nasal septum into right and left sides.  Median Nasal Septum: is composed of bony (vomer, nasal and ethmoid bones), cartilaginous, and membranous part. The septum meets the upper surface of the hard palate  3/7/2024  In the horse, the septum meets the whole length of the hard palat, so each nasal cavity communicates with the pharynx through a separate opening ( choana)  In other species, the caudal part of the septum fails to meet the palate and single opining is shared by two nasal cavities. Horse Cow 20  3/7/2024 21 Nasal cavities   The nasal cavity can be divided into three parts :  The vestibule (the rostral part).  Nasal conchae ( the middle part)  thin scroll of bone covered by mucous membrane. The passage between the conchae are called meatuses.  Ethmoturbinate ( the caudal part)  Delicate, mucosa-covered, bony scrolls (part of the ethmoid bone)  The nasal cavity is connected to paranasal sinuses and the nasopharynx. 3/7/2024 22 Nasal Vestibule   The nostril forms the opening of the nasal cavity and surrounds the nasal vestibule.  In the horse and donkey, the integument continues within the nasal cavity, and forms a sharp demarcation with the nasal mucosa.  The nasal puncta of the nasolacrimal duct is located:  In the horse, on the ventral floor of the vestibule, near to this mucosal transition.  In other species it is located more caudally, occasionally with more than one opening. 3/7/2024 23 Nasal Vestibule  3/7/2024 The nasal puncta of the nasolacrimal duct 24 Nasal conchae   The nasal conchae are cartilaginous or ossified scrolls covered with nasal mucosa that occupied most of the nasal cavity.  They have a complicated and species-specific arrangement.  In dog, the nasal conchae are more complex to increase in surface area, together with a higher number of olfactory receptor cells, accounts for the excellent olfactory sense of the dog compared to humans.  Nasal conchae is classified by topography and not by morphology into :  Ethmoidal conchae ( vascular plexi formed by multiple anastomosing vessels)  In horse, ethmoid hematoma occurs , resulting in intermittent epistaxis  Large dorsal and ventral conchae  Smaller middle conchae 3/7/2024 25 Nasal conchae  3/7/2024 26 Nasal conchae  3/7/2024 27 Nasal meatuses   The major conchae divide the nasal cavity into a series of clefts and meatuses which branch out from a common meatus near the nasal septum.  There are three nasal meatuses in the domestic mammals:  dorsal nasal meatus (narrow/between dorsal conchae and nasal bone).  middle nasal meatus between dorsal conchae and ventral conchae.  ventral nasal meatus ( largest/between ventral conchae and hard palate) 3/7/2024 28 Nasal meatuses  3/7/2024 29 Nasal meatuses  3/7/2024 30 Nasal meatuses  The dorsal nasal meatus. It leads directly to the fundus of the nasal cavity and channels air to the olfactory mucosa.  The middle nasal meatus communicates with the paranasal sinuses.  The ventral nasal meatus is the main pathway for airflow leading to the pharynx  The common nasal meatus is the longitudinal space on either side of the nasal septum. It is communicating with all the other nasal meatuses.  The pharynx can be accessed by the passage of nasogastric tubes and endoscopes through the widest point, between the ventral and common meatus. 3/7/2024 31 Paranasal sinuses   The paranasal sinuses are diverticula of the nasal cavity that excavate the skull bones to form air-filled cavities.  They are particularly well-developed in the ox and the horse and account for the conformation of the head in these species.  The paranasal sinuses are: Hypothesized to provide thermal and mechanical protection to the orbit, nasal cavity and cranial cavities  The paranasal sinuses are lined by respiratory mucosa, which is extremely thin and poorly vascularized.  This is thought to account for the poor healing capacity of this area.  Treatment is complicated due to the narrowness and locations of the openings, which make them prone to blockage when the mucosa is thickened by inflammation. 3/7/2024 32 Paranasal sinuses   The following paired paranasal sinuses can be found in the skull of domestic mammals:         3/7/2024 Maxillary sinus (rostral and caudal sinus) Frontal sinus Palatine sinus Sphenoidal sinus Lacrimal sinus in pigs and ruminants Dorsal conchal sinus Ventral conchal sinus in the pig, ruminants and horse Ethmoid cellules in pigs and ruminants. 33 Paranasal sinuses  3/7/2024 34 Paranasal sinuses  3/7/2024 35 Paranasal sinuses  3/7/2024 36 Summary   we identify Function of Respiratory System :  regulation of gas exchange  control of PH of body fluid and temperature  Nose (-olfactory receptors ): Environmental information (olfacation, orientation and protection).  Nasal cavity and conchae : warm and moisten the air and filter foreign material.  The larynx: protects the entrance to the trachea, regulates the inspiration and expiration of air and plays major role in vocalization ( phonation) 3/7/2024 37 Summary  we identify The division of respiratory System functionally :  The respiratory passages         Sites of gaseous exchange within the lungs are:     3/7/2024 External Nose Nasal Cavity Nasopharynx Larynx Trachea Bronchi Lungs Respiratory Bronchiole Alveolar Ducts Alveolar Sacs Alveoli organ location (cranial end of larynx) as following:  Upper Respiratory Tract:  The respiratory organs located within the head  nose, paranasal sinuses, nasopharynx  Lower Respiratory Tract:  consists of the larynx, the trachea and the lungs. 38 Summary  we identify the division of respiratory System functionally : organ location (cranial end of larynx) :  The respiratory passages  Upper Respiratory Tract:        External Nose Nasal Cavity Nasopharynx Larynx Trachea Bronchi Lungs  Sites of gaseous exchange     3/7/2024 Respiratory Bronchiole Alveolar Ducts Alveolar Sacs Alveoli  nose, paranasal sinuses, nasopharynx  Lower Respiratory Tract:  larynx, trachea and lungs. 39 Summary  we identify  The Nose  The external narse (nostrils) and their associated nasal cartilages and alar cartilage.  The nasal cavity  with nasal meatus and conchae.  paranasal sinuses, nasopharynx  the muzzle (nasolabial plate, Philtum and Rostrum, 3/7/2024 40 Instructor : Dr. Abdulhafeed S. Dalab PhD in Anatomy and Cell Biology Department of Veterinary Medicine Faculty of Agriculture and Veterinary Medicine June, 2021  Lower Respiratory Tract 3/7/2024 2 Larynx   The larynx is tube-shaped musculocartilagenous organ that form the connection between the pharynx and the tracheobronchial tree.  It lies below pharynx and suspended from the cranial base by hyoid apparatus. 3/7/2024 hyoid apparatus They support and stabilize the tongue and the larynx. The hyoid apparatus consists of : 1. stylohyoid 2. Epihyoid 3. Ceratohyoid 4. basihyoid 5. Thyrohyoid The basihyoid is the only single bone that connects the paired bones from each side at the root of the tongue. 3 Larynx   It protects the entrance to the trachea thus preventing aspiration of foreign material into the lower respiratory tract.  It is also important in vocalization. 3/7/2024 4 Hyoid Apparatus  3/7/2024 5 Larynx   Larynx walls are formed by laryngeal cartilages and their connecting muscle and ligament:  Cartilages of the larynx : 1. 2. 3. 4. 3/7/2024 Median epiglottic cartilage (Epiglottis) Thyroid cartilage Paired Arytenoid cartilages Cricoid cartilage  Insignificant sesamoid and interarytenoid cartilage in dog 6 Cartilages of the larynx  3/7/2024 7 Epiglottis   The rostral most cartilage  The epiglottis resembles a leaf with a small stalk and a large blade.  Its free apex pointed rostrally  Sharp in carnivores and horse  More rounded in ruminant and pig. 3/7/2024 dog Horse 8 Thyroid cartilage   The largest cartilage, single and open dorsally.   It has two lateral plates and a ventral body. It has two process's (rostral and caudal process)      3/7/2024 The rostral process articulates with the hyoid bone The caudal process articulates with cricoid cartilage. In horse : The rostral process is separated from the plate by a notch. In horse : a large caudal notch found in the floor covered by soft tissue. The laryngeal prominence is in the ventral projection of this cartilage, known as the palpable (Adams apple in human). 9 Thyroid cartilage  3/7/2024 10 Arytenoid cartilages   The arytenoid cartilages are the only paired laryngeal cartilages, which meet dorsally to cover the notch left open by the lamina of the thyroid cartilage, thus forming the major part of the roof of the larynx.  A small hyaline interarytenoid cartilage may be found between the arytenoid cartilages dorsally.  Arytenoid cartilages have number of processes:     3/7/2024 Vocal: vocal fold attaches projects ventrally Muscular: extends laterally Corniculate: rostral horn-like extend dorsomedially. Cuneiform: support mucosal folds passing from epiglottis. 11 Cricoid cartilage   The single signet ring-shaped cartilage connecting thyroid cartilage and trachea.  It has an expanded dorsal plate (lamina) and a narrower ventral arch (similar to the tracheal cartilage). 3/7/2024 12 Cartilages of the larynx  3/7/2024 13 Laryngeal cavity   The cavity of the larynx may divided into 3 sections: 1. The vestibule: extend from laryngeal entrance to the rostral process of arytenoid cartilage and vocal cord.  Lateral ventricles: lateral depression in the vestibule just cranial to the vocal folds (allow vocal folds laterally movement.  In the horse and the dog, a lateral laryngeal ventricle is formed on each side by an out pouching of the laryngeal mucosa.  Present in horse, dog and pig; absent in cat and ruminant. 2. The glottis cleft: bounded by arytenoid cartilages and vocal cord ( narrower than vestibule). 3. Infraglottic cavity: caudal to the glottis cleft and leads to the lumen of trachea. 3/7/2024 14 Laryngeal cavity  3/7/2024 15 Articulations and ligaments of the larynx   All articulations between the different laryngeal cartilages are synovial joints (permitting movement in all directions) with the exception of the articulation between the epiglottis and the rest of the larynx.  The synovial articulations between the cricoid cartilage and the arytenoid cartilages allow abduction and adduction to the arytenoid cartilages,  which results: – – 3/7/2024 in expansion of the glottic cleft during inspiration and narrowing of the glottic cleft during expiration 16 Muscles of the larynx   There are several groups of muscles:  extrinsic muscles that pass between the external surface of the larynx and the pharynx, hyoid bone, sternum and tongue,  intrinsic muscles that pass between the laryngeal cartilages.  The intrinsic laryngeal musculature consists of a set of small paired muscles that join the laryngeal cartilages.  They widen and narrow the glottic cleft and tense and relax the vocal folds. 3/7/2024 17 The intrinsic laryngeal musculature  3/7/2024      cricothyroid muscle dorsal cricoarytenoid muscle lateral cricoarytenoid muscle transverse arytenoid muscle thyroarytenoid muscle 18 The intrinsic laryngeal musculature   The dorsal cricoarytenoid muscle is the main abductor of the vocal folds, which widens the glottic cleft.  The lateral cricoarytenoid muscle: Contraction of this muscle narrows the glottic cleft.  The transverse arytenoid muscle : adduct the two arytenoid cartilage, thus narrowing the glottic cleft.  The thyroarytenoid: in horse and dog, it divided into ventricular and vocal muscle; they narrow the glottic cleft 3/7/2024 19  3/7/2024 20   The vocal ligament extends between the vocal process of the arytenoid cartilages and the body of the thyroid cartilage on either side.  It forms the basis of the vocal fold  In some horses, hemiplegia of the left recurrent laryngeal nerve results in incomplete abduction of the left arytenoid cartilage and thus the left vocal fold does not abduct sufficiently, thus producing a "roaring" sound during inspiration. 3/7/2024 21 Blood supply of the larynx   The blood supply of the larynx is provided by the laryngeal branch of the cranial thyroid artery, which extends from the cranial end of the common carotid artery.  The laryngeal branch of the cranial thyroids artery branches to form a muscular branch  which supplies:  laryngeal muscles  vocal and vestibular muscles  laryngeal mucosa. 3/7/2024 22  3/7/2024 23 Innervations of the larynx   The larynx is innervated by the vagus nerve. 1- The cranial laryngeal nerve divides into an external and internal branch. - The external branch innervates the constrictors of the pharynx and the cricothyroid muscle. - The internal branch innervates the mucosa. 2- The caudal laryngeal nerves supply motor innervations to all of the intrinsic muscles of the larynx except the cricothyroid muscle. 3/7/2024 24  3/7/2024 25 Trachea   The trachea extends from the cricoid cartilage of the larynx to its bifurcation.  It consists of a series of C-shaped hyaline cartilages connected by ligaments.  The number of the tracheal cartilages varies among individuals. 3/7/2024 26 Trachea   The tracheal cartilages are open dorsally and have different shapes in the different domestic species.  The space left by failure of these cartilages to meet dorsally is bridged by the transverse tracheal muscle and connective tissue. 3/7/2024 27 Trachea   The trachea passes from larynx, through the visceral space of the neck ventral to the cervical spine and longus colli muscle to the thoracic inlet. 3/7/2024 28 Trachea   Its continues to its bifurcation dorsal to the base of the heart.  In ruminant and pig: a separate tracheal bronchus arise proximal to the tracheal bifurcation and aerates the accessory lobe of right lung. 3/7/2024 29 Trachea   The cervical portion of the trachea maintains a median position in relation to esophagus 3/7/2024 30 Lung   The right and the left lung are grossly alike and are connected with each other at the bifurcation of the trachea.  The lungs occupy most of the thoracic cavity, and each lung is invaginated in the corresponding pleural sac.  A thin fluid-filled cleft is present between the visceral pleura and the parietal pleural, which serves to reduce friction during respiration. 3/7/2024 31 Lung   Each lung has 3 surfaces : 1. 2. 3. The costal surface: adjacent to thoracic wall Mediastinal surface: towards the mediastinum Diaphragmatic surface adjacent to the surface of the diaphragm.  Each lung has 4 borders : 1. 2. 3. 4. 3/7/2024 Dorsal border: when mediastinal and costal surface meets. Ventral border: over the heart to form (cardiac notch) Basal border: when Diaphragmatic and costal surface meets Mediastinal border: Diaphragmatic and Mediastinal surface meets 32  3/7/2024 33 Lung   The root of the lung.  The area of each lung that receives :     3/7/2024 main bronchus pulmonary vessels (pulmonary artery and vein, bronchial artery and vein lymph vessels nerves 34 Lung   The lungs are fixed in place by:     3/7/2024 their attachment to the trachea blood vessels the mediastinum the pleura, which detaches the pulmonary ligament dorsomedially to connect the lungs with the mediastinum and the diaphragm 35 Bronchial tree   The bronchi divide within the lungs dichotomously or trichotoumously, with each new generation being smaller in diameter.  Based on function, the bronchial tree can be divided into two parts:  respiratory passageways:       Site of gaseous exchange within the lungs:     3/7/2024 principal bronchi lobar bronchi segmental bronchi subsegmental bronchi true and terminal bronchiole respiratory bronchiole alveolar ducts alveolar sacs pulmonary alveolus 36 Bronchial tree  Respiratory passageways: 1. 2. 3. 4. 5. 3/7/2024 principal bronchi lobar bronchi segmental bronchi subsegmental bronchi true and terminal bronchiole 37 Bronchial tree  Site of gaseous exchange within the lungs: 1. 2. 3. 4. 3/7/2024 respiratory bronchiole alveolar ducts alveolar sacs pulmonary alveolus 38 Bronchial tree   Principal bronchi: left and right, short, thick segment divided into lobar bronchi.  Lobar bronchi: ventilating one lobe and giving rise to segmental bronchi.  Segmental bronchi: ventilating bronchopulmonary segment.  ( cone-shaped section of lung tissue within a lob) 3/7/2024 39 Bronchial tree   Bronchioles: small tubes with no cartilaginous support, the last conducting branch.  Respiratory bronchioles: terminal bronchioles whose wall contains some alveoli, therefore, they conduct and respire / present in : dog , cat and horse.  Alveolar duct: passage from respiratory bronchioles surrounded by alveoli.  Alveolar sacs; termination of alveolar duct surrounded by alveoli.  alveoli: thin walled sacs for gas exchange. 3/7/2024 40 Bronchial tree   Tracheal bronchus:  the bronchus in ruminant and pigs  arising cranial to the tracheal bifurcation  supply the right lung cranial lobe. 3/7/2024 41 Lobes of the lung   The lobes of the lung are properly defined by the ramification of the bronchial tree.  e.g. Cranial bronchus- cranial lobe, accessory bronchus- accessory lobe.  Left lung  Cranial lobe  Caudal lobe  Right lung  Cranial lobe  Middle lobe  Caudal lobe  Accessory lobe 3/7/2024 In ruminant : right cranial lobe ventilated by tracheal bronchus. 42  3/7/2024 43 Lobes of the lung  3/7/2024 44  3/7/2024 cat dog 45  ox horse 3/7/2024 46  3/7/2024 47 Blood and lymph vessels   The pulmonary arteries carry deoxygenated blood from the right ventricle of the heart to the lungs for gaseous exchange.  The pulmonary veins return oxygenated blood from the left atrium to the heart.  An additional nutritional blood supply is provided by the broncho-esophageal artery and vein.  Lymph from the lungs is drained to the tracheobronchial lymph nodes, which are situated around the tracheal bifurcation. 3/7/2024 48 Nerve supply   The lung receives parasympathetic and sympathetic nerves from a pulmonary plexus within the mediastinum.  Sympathetic fibers from the medial and caudal cervical ganglions radiate into the mediastinum.  where they unite with parasympathetic fibers from the vagus to form the cardiac plexus at the base of the heart; the cardiac plexus delivers the nerve fibers for the pulmonary plexus. 3/7/2024 49 The Pleurae  Membranes that cover the lungs and line the pleural cavity. A double-layered sac surrounding each lung Parietal pleura Visceral pleura Pleural cavity - Potential space between the visceral and parietal pleurae, filled with pleural fluid 3/7/2024 50 The Pleurae   Visceral pleura: on the lung.  Parietal pleura: on the wall on thorax, mediastinum and diaphragm.  Mediastinal pleura: on mediastinum.  Pericardial pleura: on pericardium  Costal pleura: on thoracic wall  Diaphragmatic pleura: on diaphragm. 3/7/2024 51  3/7/2024 52 we identify Summary   The larynx  hyoid apparatus      stylohyoid Epihyoid Ceratohyoid basihyoid Thyrohyoid  Cartilages of the larynx :     3/7/2024 Median epiglottic cartilage (Epiglottis) Thyroid cartilage Paired Arytenoid cartilages Cricoid cartilage  Laryngeal cavity    The vestibule The glottis cleft Infraglottic cavity  Muscle of larynx      cricothyroid muscle dorsal cricoarytenoid muscle lateral cricoarytenoid muscle transverse arytenoid muscle thyroarytenoid muscle 53 we identify Summary   Blood supply of the larynx   laryngeal branch of the cranial thyroid artery muscular branch of the cranial thyroid artery  Innervations of the larynx  Trachea   C-shaped hyaline cartilages The number of the tracheal cartilages varies among individuals.  Lung   the vagus nerve. The cranial laryngeal nerve (external and internal branch).  The caudal laryngeal nerves  Each lung has 3 surfaces :   The costal , Mediastinal and Diaphragmatic Each lung has 4 borders :  Dorsal, Ventral, Basal and Mediastinal border: 3/7/2024 54 we identify Summary   Bronchial tree  respiratory passageways:      principal bronchi lobar bronchi segmental bronchi subsegmental bronchi true and terminal bronchiole  Site of gaseous exchange within the lungs:     3/7/2024 respiratory bronchiole alveolar ducts alveolar sacs pulmonary alveolus  Tracheal bronchus in ruminant and pigs  Lobes of the lung  Left lung  Cranial lobe  Caudal lobe  Right lung     Cranial lobe Middle lobe Caudal lobe Accessory lobe 55 we identify Summary   Blood and lymph vessels  The pulmonary arteries  The pulmonary veins  broncho-esophageal artery and vein  tracheobronchial lymph nodes  Nerve supply  The Pleurae       Visceral pleura Parietal pleura Mediastinal pleura Pericardial pleura Costal pleura Diaphragmatic pleura  parasympathetic and sympathetic nerves from a pulmonary plexus 3/7/2024 56 Instructor : Dr. Abdulhafeed S. Dalab PhD in Anatomy and Cell Biology Department of Veterinary Medicine Faculty of Agriculture and Veterinary Medicine June, 2021 Digestive System Functions   Organs concerned with: 1. Reception (Prehension) of food with the lips and mouth. 2. Mechanical breaking down of the food by chewing (mastication). 3. Digestion of food stuff by enzymatic and chemical reactions. 4. Absorption of nutrients and water. 5. Elimination of wastes. 2 Digestive System   Consists of : 1. Alimentary canal (Mouth to anus) a) b) c) d) e) 2. 3. 4. 5. 3/7/2024 Mouth and pharynx Esophagus and stomach Small intestine Large intestine Anal canal Accessory glands Salivary glands Liver pancreas 3  Mouth 3/7/2024 4 Mouth   The main function of the oral cavity is the mastication of food.  the mouth includes :  Lips  Oral cavity and its walls as well as the accessory structures  Tongue  Teeth  Salivary glands 3/7/2024 5 Lips (oral fissure)   Opining of the mouth  used for  Prehension of food  Communication and suckling in newborn animals  they contain tactile hairs in some species  The form of the lips is determined by diet and feeding habits  In horse: lips used in collecting food; for this they are sensitive and mobile  In cat : teeth and tongue are more important for prehension, the lips are less mobile and much reduced in size  In dog: it can be drawn back from teeth to signal of aggression, but are incapable of food intake, the upper lip has (philtrum)  In ox and pig: the upper lip is modified to form extensive moist nasolabial plate (ox) and rostral disc (plate) in pig 3/7/2024 6  Dog 3/7/2024 Horse Sheep Cow 7 Lips (oral fissure)   They are two Musculo-membranous structure bounding the oral fissure.  the upper and lower lips are united at the angles of the mouth ( mouth commissures).  Lips are attached to the incisive bone and the incisive part of the mandible. 3/7/2024 8 Oral Cavity   The oral cavity is divided into :  Vestibule (it is the portion of the oral cavity formed by the reflection of mucous membrane from the lips and cheeks in to the gums).  Its subdivided into:    Proper oral cavity  It’s the space within the dental arcades  3/7/2024 Labial vestibule (space between teeth and lips) Buccal vestibule (space between teeth and cheeks) Bound by :     Hard palate (dorsally) Tongue (ventrally) Teeth, dental arcades and gum (laterally and rostrally) Oropharynx and soft palate (caudally) 9  3/7/2024 10 The Mouth   Species differences  In horse and ruminant:- the mouth is relatively small, and their digestive tube is long.  In carnivores:- the mouth opening is very large, and their digestive tube is short. 3/7/2024 11 Cheeks ( Buccae )   Its role is to return food that “escaped” into the vestibule, back into the central oral cavity.  The are formed by :  Buccinator muscle  Salivary glands (buccal glands)- aggregated in carnivores to form zygomatic salivary gland  Small papilla- significant in ruminant to provide protection against dryness of food ( large, caudally directed pointed papillae) 3/7/2024 12 Buccal papilla  3/7/2024 13   Dental pad  a firm ridge replacing the incisors teeth and canine teeth in the upper jaw in the ruminants only. 3/7/2024 14 Palate   The palate is a partly osseous, partly soft tissue that separates the digestive and respiratory passages of the head.  The hard palate:  Formed by the palatine processes of maxilla and incisive bones and horizontal plate of the palatine bone.  The oral side of the hard palate is covered by a thick, cornified mucosa which crossed by a series of transvers ridges  In ruminant these ridges carry papillae directed caudally to guide food backwards.  A small median swelling, the incisive papilla is located just caudal to incisors (orifice of the incisive ducts of vomernasal organ- blind canal lined by olfactory mucosa). 3/7/2024 15 incisive papilla  3/7/2024 16 The hard palate   The hard plate is divided into two symmetrical halves by shallow groove (median palatine raphe), while in the dog it is divided by median palatine crest (cleft palate). dog 3/7/2024 cow 17 The soft palate   It is continues caudally from the hard palate to intrapharyngeal opening.  It has 2 surfaces  Ventral : covered by oral mucosa  Dorsal : covered by respiratory mucosa  the intermediate layer consists of:  Closely packed salivary glands and muscles 3/7/2024 18 Tongue (lingua, glossa)   composed primary of skeletal muscle  occupies the greater part of the oral cavity and extends into the oropharynx.  Responsible for  lapping water, prehension of food, manipulating the food with mouth and swallowing.  Possesses receptors for  taste, temperature and pain  In dog its used to enhance heat loss by panting. 3/7/2024 19 divided into apex, body, and root. Tongue  1- Apex: it’s the free rostral end of the tongue. 2- Body: its the middle of the tongue attaching to the mandible.  the body is joined the oral floor by mucosal fold ( frenulum)  in carnivores: the ventral part of the tongue contains a rodshaped fibrous body called (lyssa)     extend from the tip of tongue to the root the dorsal aspect of the canine tongue is marked longitudinally by ( median groove) In cattle : the caudal part of the dorsal surface of tongue is raised to form a large prominence (torus linguae) that is defined by the transverse lingual fossa. In the horse : the tongue is strengthened by cartilage within the dorsal part of the tongue 3- Root: the caudal end of the tongue attaching to the hyoid bone. 20 Tongue  3/7/2024 21 Horse Species differences   In dog: it is wide and flat with sharp borders.  In horse: it is spatular with rounded borders.  In ruminants: it is pointed with rounded borders. 3/7/2024 22 Tongue papillae   The distribution, size, number and form are characteristic for each species.  Based on their function they are grouped into :  Mechanic papillae  Cornified, aid in licking and protect the deeper structures from injury.  Filiform papillae  Conical papillae  Marginal papillae  Gustatory papillae  covered in tasted buds 3/7/2024  Fungiform papillae  Vallate papillae  Foliate papillae 23 Tongue papillae  24 Mechanical papillae   They are more numerous than gustatory papillae  The filiform papillae  The smallest and most numerous of all papillae  The conical papillae  Larger but less frequent, Rasp-like surface  Scatterd widely over  the dorsal surface of feline tongue  At the base of the tongue in ox  Marginal papillae  Present in newborn carnivores and piglets and aids suckling 3/7/2024 25 The filiform papillae  3/7/2024 26  3/7/2024 27 The conical papillae  3/7/2024 Cat's tongue 28 Marginal papillae  3/7/2024 29 Gustatory papillae   they contains taste buds, which are sensitive to taste  There names indicate the shape  few salivary glands are situated in close proximity to these papillae.  These glands for removal of food particles from the papillae, making them ready for new food materials entering the mouth. 3/7/2024 30 Fungiform papillae   They are mushroom-shaped structures with rounded surface.  Contain taste buds on the dorsal surface of the tongue, especially at the borders  Found in equine and bovine.  have gustatory and mechanical functions. 3/7/2024 31 Tongue papillae  32 Fungiform papillae  3/7/2024 33 Vallate papillae   Large papilla surrounded by a circular cleft and do not project above the surface of the tongue.  Located on the dorsum, rostral to the root of the tongue.  Numerous taste buds are found on the sides of the papilla.  Numbers of these papillae varies with the species. 3/7/2024 34 Vallate papillae  3/7/2024 35 Foliate papillae   Series of parallel leaves separated by furrow (crypts).  Located on the lateral border of the tongue.  They are absent in ruminants but well developed in the horse and dog. 3/7/2024 36 Tongue papillae  37 Lingual muscles   Intrinsic muscles or lingual muscle proper:  They form the bulk of the tongue and consist of: 1. 2. 3. Longitudinal bundles: they extend in both superficial and deep layers, from the apex to the root of the tongue. Transverse bundles: they extend from side to side. Perpendicular bundles: they have dorsoventral orientation.  These bundles can alter the shape of the tongue during swallowing and chewing. 3/7/2024 38 Blood supply   Paired lingual artery  Sublingual artery  Sublingual vein – can easily visible on ventral side of the tongue  Used in venipuncture in clinic. 3/7/2024 39 Innervations of the tongue:   The sense of taste to the rostral two thirds of the tongue is carried by the chorda tympanic. Note: Facial nerve (VII) gives off chorda tympanic.  The sense of taste to the caudal third of the tongue is carried by the glossopharyngeal (IX) and vagus (X) nerves.  The sense of pain, temperature and tactile is carried by the lingual nerve. Note: Trigeminal nerve gives off mandibular nerve, which gives off lingual nerve.  The motor innervation to the intrinsic and extrinsic lingual muscles is carried by hypoglossal nerve (XII). 3/7/2024 40  3/7/2024 41 Salivary glands   They are paired organ that secrete saliva via their ducts into oral cavity  saliva is important for preparation of food for swallowing by lubrication and chemical digestion.  Salivary glands classified by :  Size  Major or minor  Duct length  Short or long  Secretion  Serous or mucus or both 3/7/2024 42 Minor salivary glands   Glands that present in the mucosa of the lips, cheeks, tongue, palate and sublingual floor  These glands produce mucous secretion  They are named based on location  e.g. labial, buccal gland in ruminant and zygomatic gland in dog  They have short ducts  they are only locally important 3/7/2024 43  3/7/2024 44 Major salivary glands   Located some distance from the oral cavity and empty their secretion via long duct.  Most saliva is produced by the major salivary glands  These glands produce a more watery (serous), some of them have serous-mucous(mixed) secretion.       3/7/2024 Amylase Water Mucin Salts Antibodies Glycoproteins 45 Major salivary glands   Parotid S. gland :  Unencapsulated, lobular gland  Lies at the junction of head and neck, ventral to the auricular cartilage (ear)  Well-developed in herbivores.  Secretion : mixed (serous-mucous)  In horse: it is overlays the lateral wall of the guttural pouch.  It has several lobules by the action of the facial trabeculae 3/7/2024 46   Shape of major salivary glands parotid (PG), mandibular (MG) and sublingual glands (SG) In Angora goat MD MG PG PD SG 3/7/2024 47 Parotid S. gland  PG 3/7/2024 48 Parotid S. gland duct   The major collecting ducts pass within the trabeculae to eventually join, forming a single duct (rostrally).  The parotid duct opens into the buccal vestibule (3-5 cheek tooth).  In carnivores and small ruminants: the duct passes over the lateral surface of the masseter muscle.  In horse, ox and pig: the duct passes medial to the angle of the jaw rostrally and winds around the ventral margin of the mandible to emerge at the rostral border of the masseter muscle. 3/7/2024 49 The parotid duct  3/7/2024 50 Mandibular S. gland   Located close to the angle of the jaw and is partially covered by parotid gland.  It is slightly bigger than parotid gland in dog and cat and larger in ruminants.  Shape: round or oval  Secretion : mixed (serous-mucous), but also alternate between the two. 3/7/2024 51 Mandibular s. gland duct   Single large duct, passes ventral to the mucosa of the floor of the oral cavity/ medial to mandible.  Open with the major sublingual duct near the sublingual caruncle / frenulum. Note: Sublingual caruncles : two mucosal folds that lie on either side of the frenulum of the tongue. 3/7/2024 Frenulum 52 Sublingual S. gland   It consist of two gland on either side of the tongue.  The major sublingual S. gland (monostomatic)  absent in horse  Situated more caudally but rostral to mandibular S. gland and drained by single duct  Sharing a common opining with mandibular S. gland on the top of sublingual caruncle.  The diffuse minor S. gland (polyostomatic)  Located more rostally and opens through several smaller ducts in the lateral sublingual recesses  Both sublingual glands produce a serous-mucoid secretion in which the mucous part dominates 3/7/2024 53 Sublingual S. gland  3/7/2024 54 Sublingual caruncle   Sublingual caruncle (A), mandibular duct orifice (arrow) A 3/7/2024 55 Summary  we identify  Functions of digestive system      Mouth Lips Oral cavity Tongue Salivary glands  Oral cavity    Vestibule Labial vestibule Buccal vestibule  Proper oral cavity 3/7/2024  Dental pad  the upper jaw in the ruminants only.  Palate  The hard palate     transvers ridges incisive papilla median palatine raphe cleft palate (dog)  The soft palate   Ventral : covered by oral mucosa Dorsal : covered by respiratory mucosa 56 Summary  Tongue papillae we identify  Mechanic papillae  Tongue function  Tongue division :apex, body, and root     Lyssa (dog) median groove (dog) torus linguae (cattle) the transverse lingual fossa (cattle)  Gustatory papillae     3/7/2024  Filiform papillae  Conical papillae  Scatterd widely over the dorsal surface of feline tongue  Marginal papillae  Present in newborn carnivores and piglets covered in tasted buds Fungiform papillae mushroom-shaped, Contain taste buds on the dorsal surface have gustatory and mechanical functions Vallate papillae surrounded by a circular cleft , Numerous taste buds are found on the sides Foliate papillae parallel leaves , lateral border of the tongue, are absent in ruminants , developed in horse and dog. 57 we identify Summary   Blood supply of tongue  Paired lingual artery  Sublingual artery  Sublingual vein  Nerve supply of tongue  rostral two thirds  chorda tympanic  the caudal third  glossopharyngeal (IX) and vagus (X)  sense of pain, temperature and tactile  lingual nerve  intrinsic and extrinsic lingual muscles  Salivary glands  classified by :  Size  Major or minor  Duct length  Short or long  Secretion  Serous or mucus or both  hypoglossal nerve (XII 3/7/2024 58 we identify Summary   Minor salivary glands  present in the mucosa of the lips, cheeks, tongue, palate and sublingual floor  mucous secretion  are named based on location  e.g. labial, buccal gland in ruminant and zygomatic gland in dog  They have short ducts  Major salivary glands  Most saliva is produced by the major salivary glands  These glands produce a more watery (serous), some of them have serous-mucous(mixed) secretion.  long duct 3/7/2024 59 we identify Summary   Parotid S. gland  lobular gland, several lobules by trabeculae  ventral to the auricular cartilage (ear)  mixed (serous-mucous) 3/7/2024  The major collecting ducts eventually join forming a single duct  opens into the buccal vestibule  In carnivores and small ruminants: the duct passes over the lateral surface of the masseter muscle.  In horse, ox and pig: the duct passes medial to the angle of the jaw , emerge at the rostral border of the masseter muscle. 60 we identify Summary   Mandibular S. gland  Located close to the angle of  Single large duct, passes ventral to the mucosa of the floor of the oral the jaw cavity  covered by parotid gland.  mixed (serous-mucous), but  Open with the major sublingual duct near the sublingual caruncle / also alternate between the frenulum. two. 3/7/2024 61 we identify Summary  Sublingual S. gland  It consist of two gland on either side of the tongue.  The major sublingual S. gland (monostomatic  absent in horse  The diffuse minor S. gland (polyostomatic)  Both sublingual glands produce a serous-mucoid which the mucous part dominates 3/7/2024 62 Instructor : Dr. Abdulhafeed S. Dalab PhD in Anatomy and Cell Biology Department of Veterinary Medicine Faculty of Agriculture and Veterinary Medicine June, 2021  Pharynx 3/7/2024 2 Pharynx   The common passageway for the digestive and respiratory system  It connects the oral cavity with esophagus and nasal cavity with larynx  The soft palate divides the rostral portion of pharynx into dorsal and ventral portion :  Dorsal nasopharynx  Part of respiratory channel extend from caudal nares to laryngopharynx  Ventral oropharynx  Part of digestive channel extend from oral cavity to the base of epiglottis  The tow portion meet in intrapharyngeal opening  The laryngopharynx extend from intrapharyngeal opining to the entrance of the esophagus and larynx 3 Openings of the pharynx   Pharyngeal opening  Opening from oral cavity to oropharynx  Caudal nares (choanae)  Osseous opening between caudal nasal cavity and nasopharynx  Pharyngeal opening of auditory tube  Slits in the lateral walls of nasopharynx leading to auditory tube  Laryngeal opening  Opining into larynx  Esophageal opening  Opening at the caudal end of the laryngopharynx into esophagus 3/7/2024 4  3/7/2024 5 Pharynx   In horse : the soft palate is extremely long, it lies ventrally and in front of the tip of epiglottis.  So the horse unable to voluntarily raise its soft palate, it exclusively breathes through their nose.  This explains why horses vomits through their nose 3/7/2024 6  3/7/2024 7 Cranial part of the alimentary canal  Esophagus and stomach 3/7/2024 8  Esophagus 3/7/2024 9 Esophagus   Tube between the pharynx and the stomach  Begins dorsal to the cricoid cartilage of larynx and ends at the cardia of the stomach  At its origin it passes dorsal to the trachea  At thoracic inlet it comes to lie on the left lateral aspect of the trachea  Within the thoracic cavity it is located dorsal to the trachea, over tracheal bifurcation.  Within the abdominal cavity it is located at the dorsal border of the liver to join stomach at the cardia 3/7/2024 10 Esophagus  Begins dorsal to the cricoid cartilage of larynx and ends at the cardia of the stomach At its origin it passes dorsal to the trachea 3/7/2024 11 Esophagus  At thoracic inlet it comes to lie on the left lateral aspect of the trachea 3/7/2024 12 Esophagus  Within the thoracic cavity it is located dorsal to the trachea, over tracheal bifurcation. 3/7/2024 13 Esophagus  Within the abdominal cavity it is located at the dorsal border of the liver to join stomach at the cardia 3/7/2024 14 Esophagus   Since it traverses most of the neck, all of thorax and ends on entering the abdomen, it is divided into  Cervical part  Thoracic part  Abdominal part  In ruminant and horse : the lumen of the esophagus narrows at the thoracic inlet and esophageal hiatus of diaphragm  Predisposes this species to choke at those sites  In carnivores : they are prone to mega- esophagus or dilatation of esophagus before it enters the abdomen 3/7/2024 15  Stomach 3/7/2024 16 Stomach (gastric or ventriculus)   It is a large dilatation of the alimentary canal, caudal to the diaphragm located between the esophagus and duodenum. 3/7/2024 17 Classification of the stomach  1. According to the external shape and size or according to the number of cavities  (Monolocular stomach)  (Multilocular stomach) 2. According to the mucous membrane lining  Simple stomach  Compound stomach 3/7/2024 18 Classification of the stomach  According to the external shape and size or according to the number of cavities: Monolocular stomach:- it is containing one cavity in (dog, horse, pig) all animals except ruminants.  Multilocular stomach:- it is containing many cavities, in ruminants (ox, sheep and goat). 3/7/2024 19 Classification of the stomach Multilocular stomach 3/7/2024  Monolocular stomach 20 Classification of the stomach   According to the mucous membrane lining: Stomachs are line by glandular epithelium, and non glandular epithelium or both.  Simple stomach: is lined by one kind of mucosa (glandular mucosa) that covered by simple columnar epithelium, in dog, cat and man.  Compound stomach: is lined by glandular (simple columnar epithelium), and non glandular mucosa (is a continuation of stratified squamous epithelium of esophagus) in horse, ruminants and pigs. 3/7/2024 21 Classification of the stomach   In horse:  the non- glandular region extends for a distance and then its transform to glandular region, these two regions are separated by an irregular folded edge of mucous membrane called Margo plicatus.  In ruminants:  the proximal three compartment (rumen, reticulum and omasum) are non-glandular therefore are called forestomach or proventriculus,  the distal compartment (abomasum) is glandular portion similar to the simple stomach of other species, therefore is called true stomach. 3/7/2024 22  3/7/2024 23  3/7/2024 Horse stomach 24 Parts of simple stomach  The form of the simple stomach is a J shape curved sac, which composed of: 1- Greater curvature: the long convex surface of the stomach extending from the cardia to the pylorus, it’s the attachment site of the greater omentum. 2- Lesser curvature: the short concave surface of the stomach also extending from the cardia to the pylorus, it’s the attachment of the caudal edge of the lesser omentum. 3/7/2024 25 Parts of simple stomach  3- Cardia: it consist of the cardiac opening (the opening between esophagus and stomach and consists of bundles of circular smooth muscle fibers). -fixed part of stomach 4- Fundus: is a blind expanded portion of the stomach on the left side adjacent to the cardia ( blind sac- homologus to forestomach in ruminant)). 5- Body: is the largest part of the stomach extending from cardia to the pylorus. 6- Pylorus: is the distal opening of the stomach surrounded by a strong band of circular smooth muscle fiber (pyloric sphnicter) through which the stomach contains are emptied into the duodenum. 26  Lesser curvature Greater curvature 3/7/2024 27 Gastric glands   The stomach can be divided into 3 regions based on specific distribution of different type of gastric glands  Region of cardiac glands  Secret mucus for protection  Region of fundic (gastric) glands  Neck cells produce mucus  Chief cells produce pepsinogen  Parrietal cells produce chloride and hydrogen  Region of pyloric glands 3/7/2024 28  3/7/2024 29  3/7/2024 30 Species differences   Dog: the stomach is C- shaped , the cardia is wide, which may be related to the ease with the dogs vomit, in addition to gastric volvulus is relatively common, especially in large breeds  Cat : the stomach is C-shaped but has narrower lumen than the dog, the angular notch is deep, make it difficult during endoscopy 3/7/2024 31  3/7/2024 32 Species differences   In horse: the stomach is small, its capacity is between 5-15 L, which has to taken into account when administration of nasogastric tube to avoid over distension  Blind sac (saccus caecus) : extensive fundus lined by non glandular mucosa homologues to forestomach of ruminant  In some horses non-glandular regions is marked by scars from larvae of gastrophilus.  The cardiac sphincter is especially well developed and this , together with the oblique entrance of esophagus , is thought to be responsible for the reputed inability to vomit 3/7/2024 33  3/7/2024 34 Compound stomach   The stomach of domestic ruminants is composed of four chambers:  Rumen  Reticulum  Omasum  Abomasum  Rumen, Reticulum, Omasum are referred to as forestomach (proventriculus)  Non-glandular mucosa  Responsible for the enzymatic destruction of carbohydrates (cellulose) with the help of microbes  The last chamber, the abomasum, has a glandular mucosa and is comparable to simple stomach of horse and dog. 3/7/2024 35      3/7/2024 Rumen: lies on the left. Reticulum: lies on the cranial. Omasum: lies on the right. Abomasum: lies ventrally. 36 Rumen   Is a large laterally compressed sac it extends from the diaphragm to the pelvic inlet, filling the left half of the abdominal cavity.  The rumen is divided into several portions by inflections of the walls called the pillars of rumen that project into the lumen:      3/7/2024 Ventral sac Dorsal sac Cranial sac (atrium ) Caudodorsal blind sac Caudoventral blind sac 37 Rumen  3/7/2024 38  3/7/2024 39  3/7/2024 40 Rumen  3/7/2024 41 Rumen   The non- glandular mucosa of rumen consist of papillae (ruminal papillae)  To increase surface area 7 fold  Important in reabsorption of volatile fatty acids  Reabsorption of water, vitamins K and B  Short or long size of this papillae is depending on  Animal diet  Seasoms 3/7/2024 42  3/7/2024 43 Openings of the rumen   Cardiac orifice: is the opening of the esophagus into the stomach.  Rumeno-reticular orifice : is the opening which communicate the cranial sac with the reticulum. 3/7/2024 44 Reticulum   Is the most cranial compartment of the ruminal stomach.  Lies between the diaphragm and the rumen.  The non-glandular mucosa of the reticulum forms permanent crest, which intersect to form honey comb like cells.  each cell is divided by a secondary crests (ridge) and both the cell and the crest are studded with small papillae. 3/7/2024 45 Reticulum  3/7/2024 46  3/7/2024 47 Omasum   Round organ located chiefly to the right of the median plane.  Communicates with reticulum through the reticulo-omasal opening and with abomasums through the omaso-abomasal opening.  omaso-abomasal opening: flanked by 2 mucosal folds to prevent reflux of ingesta from abomasum into omasum.  The omasum is larger than the reticulum in ox, and smaller than the reticulum in sheep and goats.  Arising from the wall parallel folds of varying sizes called omasal laminae (They are thin muscular sheet).  For water reabsobtion 3/7/2024 48 Omasum  3/7/2024 49  3/7/2024 50 Omasum  3/7/2024 51 Omasum   These laminae are covered by short papillae.  Between the laminae are the interlaminar recesses. 3/7/2024 52 Abomasum   It is an elongated sac.  It can be divided into fundus, body and pylorus (simple stomach)  lies chiefly in the floor of the abdominal cavity  The abomasum is lined with glandular mucosa.  Gastric glands  Pyloric glands  The mucosa is arranged in large permanent spiral folds (10 to 17).  The pyloric sphincter is not very well developed in ruminants, however, a large torus pyloricus is present. 3/7/2024 53 Abomasum  3/7/2024 54  3/7/2024 55 Abomasum  3/7/2024 56 Gastric groove   Channel through stomach in suckling ruminants.  The gastric groove is divided into :  Reticular groove  Omasal groove  Abomasal groove  Suckling with head up causes lips of this groove to close, this form a tube from the cardiac opening to the abomasum  through this tube, milk bypasses the rumen , reticulum and omasum to empty directly into the abomasum 3/7/2024 57 Gastric groove  3/7/2024 58 Blood of the simple stomach (horse)   The stomach is supply by celiac artery which arises from the ventral aspect of the abdominal aorta, it divided in to three main branches:  Left gastric artery.  Hepatic artery.  Splenic artery. 3/7/2024 59 Blood supply of the compound stomach   Right ruminal artery.  Left ruminal artery. 3/7/2024 60 Instructor : Dr. Abdulhafeed S. Dalab PhD in Anatomy and Cell Biology Department of Veterinary Medicine Faculty of Agriculture and Veterinary Medicine June, 2021  Intestine 3/7/2024 2 Intestine   The intestine is the caudal part of the alimentary canal.  Intestine extend from the pylorus of the stomach to the anus.  the proximal part of the intestine has small lumen and its mucous membrane bear villi which is called small intestine  while the distal part of the intestine has wider lumen and its mucous membrane has no villi which is called large intestine. 3 Intestine  Rectum Small intestine Pancreas Rumen Omasum Esophagus Reticulum Large intestine Cecum 3/7/2024 Liver Gall bladder Abomasum 4 Intestine   It is divided into :  Small intestine: from the pylorus to the caecum  Duodenum  Jejunum  Ileum  Large intestine : from caecum to the anus  Blind caecum  Colon  Rectum 3/7/2024 5 Small intestine   The main function:  Digestion- enzymatic destruction of ingested materials into particles ready for absorption.  Both the pancreatic (enzymes) and bile (emulsification of fat) ducts open into small intestine.  Small intestine is connected to the dorsal abdominal wall by dorsal mesentery (root).  Mesentery is relatively long – allows a great degree of mobility to the small intestine  In horse and ruminant , the duodenum is fixed into its position by short mesoduodenum. 3/7/2024 6  3/7/2024 7 Duodenum   It can be subdivided into : 1. 2. 3. 4. 5. 6. 3/7/2024 Cranial portion Cranial duodenal flexure Descending portion Caudal duodenal flexure (transverse portion) Ascending portion Duodenal jejunal flexure 8   The initial portion (cranial) passes toward the right abdominal wall before deflecting caudally to descend to the pelvic inlet  It then passes medially around the cranial root of the mesentery before ascending cranially for a short distance  It ends by bending ventrally where it is continued as jejunum.  The caudal end of duodenum is marked by the cranial border of the duodenocolic fold. 3/7/2024 9 Duodenum   The duodenum is attached to abdominal roof by mesoduodenum  Short in horse and ruminant  Longer in carnivores and pig  longer mesoduodenum+ extensive lesser omentumresponsible for high prevalence of gastric torsion in dog  the mesentery of descending duodenum includes the right lobe of the pancreas.  The ascending and descending parts of duodenum form U shaped loop around the root of the mesentery 3/7/2024 10  dog ox 3/7/2024 11 horse Jejunum   Is the longest part of the small intestine, it begins at the duodenojejunal flexure and ends with ileum.  The most mobile and free part of entire alimentary canal, due to long mesojejunum.  It runs ventrally and caudally, forming many coils occupying the ventral abdominal cavity.  In ruminant, the rumen pushing the intestine to the right, thus the position of jejunal coils depends on fullness of the rumen and the size of the uterus  In horse most of the jejunum is found within the left dorsal part of the abdomen. 3/7/2024 12  dog ox 3/7/2024 13 horse jejunal coils  3/7/2024 14 Ileum   The short terminal part of the small intestine.  Its more muscular and firmer than jejunum.  It is suspended by mesentery called (mesoileum).  It attached to the cecum by ileocecal fold.  It terminates at the cecocolic junction forming ileal orifice on the ileal papilla. 3/7/2024 15 Ileum  3/7/2024 16  3/7/2024 17  3/7/2024 18  3/7/2024 19 Large intestine   It is site for dehydration of fecal contents by absorbing water.  it is extends from the ileum to anus.  It is divided into  Cecum  Colon  Ascending colon  Transvers colon  Descending colon  Rectum, and anal canal.  not as long as small intestine, but larger in diameter. 3/7/2024 20 Cecum   The cecum is a blind cylindrical sac at the junction of the small and large intestines.  Joined to the colon at the ileal orifice.  Position:  In all domestic species, the ceca are located on the right side of the abdominal cavity. 3/7/2024 21  3/7/2024 22  Species differences: Cecum   The ceca are vary with the species: Dog:  Is slightly S-shaped blind tube  Cat:  Is a comma- shaped.  Horse:  It is coma- shaped that consist of base, body and apex.  Ruminants:  is an irregular twisted tube. 3/7/2024 23  dog ox 3/7/2024 24 horse Horse cecum  It consist of :   base : dorsally, it lies in the right dorsal part of the abdomen (lumbar region)  Curved body lies against the right flank and runs cranioventrally.  Blind-ending apex: cranioventrally, close to xiphoid cartilage. 3/7/2024 25 Base  Body Sacculations Apex Horse cecum  3/7/2024 27 Horse cecum   the longitudinal layer of muscle layer is concentrated in bands visible on external surface as. Bands (taenia), between which the cecal wall is ruffled into 4 rows of sacculations (haustra)  there are 4 taenia over most of caecum     3/7/2024 Medial Lateral Dorsal Ventral 28  3/7/2024 29 Ruminant caecum   relatively small caecum.  Featureless and has neither taenia nor haustra  Located in the right half of the abdomen, its blind apex pointed caudally. 3/7/2024 30 Colon   Following human anatomic nomenclature, the colon is divided into :  Ascending colon  Transverse colon  Descending colon . The anatomical arrangement which forms the base of this division only found in dogs and cats 3/7/2024 31 Colon of dog and cat   the short ascending colon passes cranially on the right  the transverse colon runs from right to left , cranial to the root of mesentery  The long descending colon passes left o the mesenteric root caudally, where it reach the pelvic cavity to become rectum 3/7/2024 dog 32 Colon   In other domestic mammals the form and topography of colon is more complex, with the ascending colon showing the greatest modification 3/7/2024 33 Colon of horse   It consists of a large ascending colon  arranged in two U-shaped loop laying on the top of each other  Short transverse colon  Long descending colon  Due to the considerable difference in diameter; the first two portions are referred to (large colon), the third as ( small colon) 3/7/2024 34 Colon of horse   Ascending colon can be subdivided into  4 parallel limbs connected by 3 flexures  Right ventral colon  Ventral diaphragmatic flexure  Left ventral colon  Pelvic flexure  Left dorsal colon  Dorsal diaphragmatic flexure  Right dorsal colon 3/7/2024 35  3/7/2024 36 Colon of horse   The right ventral colon  Begins at caecocolic opining  Continues cranio-ventrally  When reaching xiphoid region it is deflected as ventral diaphragmatic flexure and passes caudally as left ventral colon  just cranial to pelvic cavity it forms the pelvic flexure by turning 360 degree dorsally as left dorsal colon  Then runs cranially again on top of left dorsal colon towards the diaphragm, where it become right dorsal colon after diaphragmatic flexure then it deflected medially to become the transverse colon  3/7/2024 37   Displacement of ascending colon  The start of the right ventral colon is connected to the base of the cecum  The end of the right dorsal colon is attached to transverse colon  The rest of ascending colon is free to move and possible twist on itself  Diagnosed by rectal palpation 3/7/2024 38 Colon of horse   the different portions of ascending colon can not only be distinguished by their topography, but have other characteristic features which is important for the identification of the different parts during laparotomy Right and left ventral colon have 4 bands + 4 sacculation At the junction of pelvic flexure , the 4 bands disappear. Left dorsal colon have only 1 band Right dorsal colon, shortest and widest, therefore it is referred as ampulla coli  Right dorsal colon have 3 bands     3/7/2024 39  Right and left ventral colon have 4 bands + 4 sacculation At the junction of pelvic flexure , the 4 bands disappear. Left dorsal colon have only 1 band Right dorsal colon, shortest and widest, therefore it is referred as ampulla coli  Right dorsal colon have 3 bands     3/7/2024 40 Colon of horse   Transverses colon  Passes from right to left cranial to the root of mesentery  its marked by 2 bands 3/7/2024 41  3/7/2024 42 Colon of horse   Descending colon  Similar to jejunum in diameter  Suspending by long mesentery  mesentery has higher fat than mesentery of jejunum  It has 2 bands 2 sacculations 3/7/2024 43  3/7/2024 44  3/7/2024 45 Colon of ruminant   Colon is divided into  ascending , transverse and descending colon  The ascending colon is the longest part and has spiral arrangement.  After leaving the cecum it forms sigmoid flexure  The first part being cranially convex  The second part caudally convex  It then narrows and turns ventrally to form a double spiral 3/7/2024 46 Colon of ruminant   in ox  Two centripetal turns are reversed in the central flexure and succeeded by 2 centrifugal turns  in sheep  Three centripetal turns are reversed in the central flexure and succeeded by 2 centrifugal turns  The last centrifugal coil separats from the spiral loop passes near the jujnal coils  in goat  Four centripetal turns are reversed in the central flexure and succeeded by 2 centrifugal turns 3/7/2024 47  3/7/2024 48 Colon of ruminant   The short transverses colon crosses the midline cranial to mesenteric root and continues caudally as descending colon.  This part (descending colon) is usually embedded in fat and before joining the rectum at pelvic inlet it forms a sigmoid flexure, the looseness of which allows a considerable range of movement to the hand of examiner during rectal palpation 3/7/2024 49  3/7/2024 50 Rectum   By entering the pelvis the descending colon becomes the rectum  Most of rectum is suspended by mesorectum  Before joining the short anal canal, which opens to outside with anus, it become dilatated to form rectal ampulla. 3/7/2024 51  3/7/2024 52 Anal canal   The short anal canal is the terminal part of the alimentary canal which opens to outside with anus  The anus is controlled by the internal and external sphincters  The internal sphincter: consist of smooth muscle and modification of circular layer of muscle of rectum  The external sphincter: is striated muscle arising from the caudal vertebrae 3/7/2024 53 Anal canal of carnivores   In carnivores  the mucosa of the anal canal is divided into 3 consecutive annular zones, these from cranial to caudal  Columnar zone ( rich in lymphoid tissue)  Intermediate zone ( opining of anal glands and tubuloalveolar glands- produce fatty secretion )  Cutaneous zone ( opening of the excretory ducts of anal sacs 3/7/2024 54 Anal canal of carnivores   Anal sacs (paranal sinus)  Pea- sized sacs located between inner smooth and outer striated sphincter muscle of anus  Their wall contain glands of anal sac  These glands discharge their foul- smelling, serous-to pasty secretion into the anal sacs  The secretion if important in territorial marking  Secretion of anal sacs may accumulate forming abscess and causing constipation 3/7/2024 55 Anal canal of carnivores  3/7/2024 56 Instructor : Dr. Abdulhafeed S. Dalab PhD in Anatomy and Cell Biology Department of Veterinary Medicine Faculty of Agriculture and Veterinary Medicine June, 2021 Glands associated with the alimentary canal  Liver, Pancreas and Gall bladder 3/7/2024 2   Liver and pancreas are two glands closely associated with the alimentary canal  Both organs produce substances which paly a central role in gastrointestinal digestion 3/7/2024 3  Liver 3/7/2024 4 Liver   Is the largest gland of the body and is both exocrine and endocrine in function.  Its exocrine product, bile, is stored in gall bladder  Responsible for emulsifying the fatty compounds prior to absorption  Its endocrine substances are released into the blood  Important in fat, carbohydrate and protein metabolism 3/7/2024 5 Functions  1- Metabolism of protein, carbohydrate and fats. 2- Detoxification of drugs and toxins. 3- Plasma protein production. 4- Formation and secretion of bile. 5- Hemopoiesis in the embryo. 3/7/2024 6 Liver  Color of liver in different species :  In the ox, sheep and horse:  Is reddish brown, but becomes brown when bled out.  In the dog and cat:  The liver is reddish brown.  Suckling and pregnant animals:  They have a yellowish brown liver, because of the presence of fats.  In starving animals:  They have a dark reddish brown liver. 3/7/2024 7 Liver  Position:  Located in thoracic part of the abdomen, immediately behind the diaphragm.  The bulk of the liver lies to the right of the median plane 3/7/2024 8 Position of liver varies with species   In dog :  The liver located equally on each side of the median plane.  In the ruminants :  Is displaced entirely to the right of the abdominal cavity, the round border lies in the median plane and the sharp border is directed to the right.  In horse :  The liver is placed obliquely, its rounded border crosses the median plane and faces dorsolaterally and to the left, while its sharp border is directed ventrolaterally and to the right. 3/7/2024 9 Liver   It has strong convex surface toward the diaphragm (Diaphragmatic surface)  It has a concave surface facing toward the abdominal organs (Visceral surface)  The visceral surface is marked by hepatic porta (portal vein, bile duct and hepatic vessels enter or leave the organ  the two surfaces meet ventrolaterally in sharp- edged border and dorsally in blunt border 3/7/2024 10  Hepatic porta : Is the depression on the visceral surface of the liver through which the portal vein, hepatic artery and hepatic ducts are passes 3/7/2024 11 Liver   In most species the liver is grossly divided into four main lobes     3/7/2024 Left hepatic lobe Right hepatic lobe Caudate lobe Quadrate lob 12 Lobation of the liver  The liver can divided to its lobes according to the following base: 1- Imaginary line on the visceral surface from the esophageal notch to the notch for the round ligaments separates the left lobe from the rest of the liver. The left lobe may be subdivided in to left medial and left lateral lobes. 2- Another line from the caudal vena cava to the fossa for the gall bladder, separate the right lobe from the rest of the liver. The right lobe may be subdivided in to right medial and right lateral lobes. 3/7/2024 13  The region between these lines divided the liver in to: A- Quadrate lobe : It lies ventral to the hepatic porta. B- Caudate lobe : It lies dorsal to the porta and has caudate and papillary processes. 3/7/2024 14  3/7/2024 15 Lobation patterns   Lobation patterns differ greatly among species.  Species in which spine is very mobile, such as dog and cat, have more subdivision than species with a more rigid spine (herbivores)  It is hypothesized that the hepatic lobes easily glide over each other, when the spine is maximally flexed or extended. 3/7/2024 16 Lobation patterns   In carnivores: liver has 4 lobes and 4 sublobes and 2 processes  Left and right hepatic lobe  Subdivided into medial and lateral lobes  Caudate lobe  Subdivided into caudate and papillary processes  Quadrate hepatic lobe 3/7/2024 17 Dog  3/7/2024 18 Lobation patterns   In the horse: liver has 4 lobes and 2 sublobes and 1 processes  The left lobe only subdivided into medial and lateral lobes  The right lobe remains un divided  The caudate lobe has caudate process, but no papillary process  Quadrate lobe 3/7/2024 19 Horse  3/7/2024 20 Lobation patterns   In ruminant: liver has 4 lobes and 2 processes  Left hepatic lobe  Right hepatic lobe  Caudate lobe  Subdivided into caudate and papillary processes  Quadrate lob  it has no fissures 3/7/2024 21 Ruminant  3/7/2024 22 Sheep  Liver of a sheep: (1) right lobe, (2) left lobe, (3) caudate lobe, (4) quadrate lobe, (5) hepatic artery and portal vein, (6) hepatic lymph nodes, (7) gall bladder 3/7/2024 23 Blood supply of the liver  1- Functional blood :  It comes to the liver via the portal system (portal vein), caring nutrient absorbed from the intestine.  Portal vein: the large vein caring all the blood from the abdominal viscera to the liver. 2- Nutrient blood (oxygenated) :  It comes to the liver via hepatic artery to keep the hepatocytes alive. 3/7/2024 24  3/7/2024 25 Bile passages  3/7/2024 26 Bile passages  1- Bile ductules: They unite to form hepatic ducts. 2- Hepatic duct: Three to five duct that leave the porta and form common hepatic duct. 3- Cystic duct: It connects the gall bladder with the common hepatic duct. 4- Bile duct: The duct formed by the junction between the common hepatic duct and cystic duct 3/7/2024 27 Species differences   In ruminants:  The common hepatic duct unit with the cystic duct to form the bile duct.  In horse:  The gall bladder and its cystic duct are absent, therefore the wider terminal portion of the common hepatic duct is called the bile duct.  In dog:  Three to five common hepatic ducts empty separately in to the cystic duct, which becomes the bile duct. 3/7/2024 28 Gall bladder  1_The sac storing and concentrating bile. 2_ It lies in the fossa on the visceral surface of the liver between the quadrate and right medial lobes. 3_ The bile aids in digestion and lubrication of food. 4- horse has no gall bladder 3/7/2024 29 Pancreas   Like the liver, the pancreas has both exocrine and endocrine function  The exocrine product, the pancreatic juice, is conveyed to duodenum by one or more ducts, depending on the species.  the pancreatic juice is important for reduction of proteins, carbohydrates and fat.  The endocrine part produce insulin, glucagon and somatostatin and pancreatic polypeptide 3/7/2024 30 Pancreas   The pancreas located in the dorsal part of the abdominal cavity in close relationship to the proximal part of the duodenum (descending duodenum)  It can be divided into  Body  Right lobe  Left lobe 3/7/2024 31 Pancreas   In carnivores :  it has V –shaped form consisting of two limbs that emerge from the body  the left limb is shorter, but thicker than the right limb runs within greater omentum  The right limb is longer and follows the descending duodenum within the mesoduodenum. 3/7/2024 32  3/7/2024 33 Pancreas   In the horse :  It has triangular outline with large, compact body  Short right lobe  Long left lobe  It is perforated by the portal vein in pancreatic ring 3/7/2024 34  3/7/2024 35  In ruminant Pancreas   Short body  Short right and left lobe  The right lobe is larger and follows the mesentery of the descending part of the duodenum  The portal vein passes in the pancreatic notch 3/7/2024 ox 36  3/7/2024 Sheep pancreas 37 Pancreas  Ducts of the pancreas : 1- Pancreatic duct : The tube opening with the bile duct on the major duodenal papillae. (Accessory pancreatic duct) Pancreatic duct 2- Accessory pancreatic duct : The tube opening in to the duodenum on the minor duodenal papillae. 3/7/2024 38 Pancreas  3/7/2024 39  3/7/2024 40 Species differences  Dog Horse Ox Sheep and goat Pancreatic duct + + - + Accessory pancreatic duct + + + - + present - Absent Since the both communicate inside the gland, the absence of one duct has no significance. Blood supply   The right lobe:  Cranial pancreatoduodenal a.  the left lobe:  Caudal pancreatoduodenal a.  Splenic a. 3/7/2024 42