Splanchnology

• Splanchnology


  The study of the organs responsible for the maintenance and perpetuation of the individual
• Organs under maintenance

  • Digestive system
  • Respiratory system
  • Excretory (urinary) system
• Organs under perpetuation of the individual

  • Reproductive system
• Digestive system


  Concerned with nutrition of the body and this includes prehension of food, mastication, digestion, absorption, storage of nutrients and excretion of unabsorbed portion of the food
• Digestive apparatus


  • Oral cavity
  • Pharynx
  • Alimentary canal (esophagus, stomach, small intestine and large intestine)
  • Accessory organs
• Accessory organs

  • Salivary glands
  • Liver
  • Gall bladder
  • Pancreas
  • Anal sac
• Mouth


  Designates the oral cavity and its walls
• Oral cavity


  • Concerned with prehension, selection, mastication and insalivation of food; in short, with the conversion of food to a bolus that can be swallowed by the individual
  • Extends from the lips to the entrance of the pharynx
• Divisions of the oral cavity


  • Vestibule
  • Oral cavity proper
• Vestibule


  • The space external to the teeth and gums and internal to the lips and cheeks
• Oral cavity proper


  • Assists in sucking and in prehension of food
  • Bounded by lips, cheeks, teeth, gums, margins of the jaw, hard palate, tongue and reflected mucosa
• When the mouth is closed, the vestibule and oral cavity proper communicate via the interdental spaces, especially the large space (diastema) between the incisors and the cheek teeth
• Other structures in the oral cavity

  • Oral fissure
  • Openings of the parotid and zygomatic salivary ducts (parotid papilla)
  • Sublingual caruncle
  • Sublingual fold
  • Incisive papilla
  • Incisive duct
• The oral cavity is continuous caudally with the isthmus of the fauces and with the oral pharynx
• Oral fissure


  A U-shaped slit between the lips where the vestibule opens to the outside anteriorly; the external opening of the oral cavity
• Openings of the parotid and zygomatic salivary ducts

  • Parotid papilla
• Sublingual caruncle


  • The inconspicuous opening of the sublingual and mandibular ducts located under the body of the tongue
• Sublingual fold


  • A low ridge of mucosa extending caudally from the caruncle to about a transverse plane through the lower shearing teeth
• Incisive papilla


  • Caudal to the upper central incisor, it is a rounded eminence extending caudally to blend with the first transverse ridge of the hard palate mucosa
• Incisive duct


  • Opens on each side of the papilla, connects the oral cavity to the nasal cavity and vomeronasal organ
• The oral cavity is continuous caudally with the isthmus of the fauces and with the oral pharynx
• Lips (Labia oris)


  • Bounding the oral fissure, they form the rostral and most of the lateral boundaries of the vestibule. The lips of the dog are extensive but thin, and are not capable of purposeful movements
• Aside from its main functions (prehension, mastication, and insalivation of food), the mouth may also play a role in aggression and defense. In most species, it functions as an airway when flow through the nose is impaired
• Upper and lower lips

  • Meet at the angles of the mouth forming the commissures of the lip. The lower lip is noticeably smaller than upper lip
• Philtrum ('nose leather')


  • A deep, straight, narrow median cleft marking the union of the two halves of the upper lip, anteriorly
• Tactile hairs


  • Thinner and shorter in front, longer and thicker farther back. On the upper lip and adjacent part of the muzzle, these are arranged in four rows
• Cheeks (Buccae)


  • They form the caudal portion of the lateral walls of the vestibular cavity. The principal support is the buccinator muscle (important function of returning to the central cavity any food that has escaped into the vestibule)
• Cheeks


  • They are small in the dog, lie medial to the masseter and extend as far as the attachment of the buccinator muscles on the mandible and maxilla opposite the last two cheek teeth and of the coronoid process
• Cheeks


  • Also associated with the zygomatic gland, concealed below the zygomatic arch
• Cheeks


  • Consist of three layers (continuous with lips):
• Cheeks


  • Two coarse tactile hairs project caudolaterally from the caudal part of the skin
• Buccal glands


  • Dorsal and ventral, located between the musculature and mucosa of the cheek
• Palate (Palatum)


  • It is a partly bony, partly membranous partition separating the respiratory and digestive passages of the head
• Hard Palate (Palatum durum)


  • Represents the osseous palate and the mucosa that covers its oral surfaces. It is larger and nearly flat, inclined slightly ventrally on its lateral and rostral portions. It is formed by the palatine processes of: 1. Palatine, 2. Maxilla, 3. Incisive. The mucosa is thrown into two rows of transversely oriented palatine ridges, the which meet at the median palatine raphe. The rugae may guide the food backward
• Soft Palate (Palatum molle/Velum palatinum)


  • It is a substantial musculomucosal shelf which forms the caudal continuation of the hard palate. It is long in dog and the epiglottis is usually seen lying above the thick caudal border of the soft palate. In brachycephalic breeds, the soft palate is so long as to interfere with the passage of air into the larynx
• Palatopharyngeal arch


  • Or the caudal pillar of the soft palate formed by the palatopharyngeal muscle and the mucosa
• Palatoglossal fold


  • A fold formed on the side of the mouth running from the body of the tongue to the initial part of the soft palate
• Palatine veil


  • The portion of the soft palate caudal to a transverse plane through the caudal borders of the pterygoid bones
• Layers of the soft palate

  • Stratified squamos epithelium, 2. Palatine glands- form the thickest layer of the organ, 3. Muscles of the soft palate
• Masticatory apparatus


  Comprises the teeth and gums, the temporomandibular and symphysial joints of the jaws, and the masticatory muscles