Dig Sys 1

• The digestive system anatomy of domestic animals and poultry includes the mouth, oral cavity, pharynx, esophagus, stomach, small and large intestine, liver, and pancreas.
• Key references for studying this include König-Liebich's Veterinary Anatomy of Domestic Animals and Illustrated Veterinary Anatomical Nomenclature.

Mouth (Os s. Stoma)

• The mouth consists of the lips (Labia oris), oral cavity (Cavum oris), accessory structures (teeth, palate, tongue), and salivary glands.

Lips (Labia oris)

• Lips are composed of skin, muscle, tendon, glands, and oral mucosa.
• The upper and lower lips are known as Labium superius et inferius.
• The mouth opening or slit between the lips is called the Rima oris.
• The Commissura labiorum is where the two lips meet.
• The Bucca, or cheek, contains the m.buccinator, salivary glands, and loose mucosa.
• Horse lips are highly mobile with a large upper lip covered in fine hair. They contain very sensitive tactile and prehensile organs to collect food.
• Cow: has a thick, modified skin area known as the nasolabial plate, or planum nasolabiale
• Carnivores and small ruminants have a medial groove called the philtrum in their upper lip.
• Pig: has a rostral plate or disc called planum rostrale, which equals the labium superius plus rostrum.

Vestibule (Vestibulum oris)

• The vestibule is the space between the dental arch and cheeks/lips.
• The labial vestibule (vestibulum labiale) refers to the space between teeth and lips,
• The buccal vestibule (vestibulum buccale) is found between teeth and cheeks.
• Ruminants' inner lip and cheek surfaces have large, backward-pointing papillae, most prominent toward the mouth's corners.
• These include Papillae labiales and Papillae buccales.

Proper Oral Cavity (Cavum oris proprium)

• This is space is within the dental arch, limited caudally by the Arcus palatoglossus.
• Structures: palate (palatum), teeth (dentes), tongue (lingua) and salivary glands.
• Mucous Membrane: Lines the oral cavity, consisting of stratified squamous epithelium penetrated by submucousal gland ducts.
• Gum (Gingiva): Modified mucous membrane attached to the teeth and alveolar bone.

Palate (Palatum)

• The palate is a partly osseous and partly soft tissue partition separating the digestive and respiratory passages.
• The hard palate (Palatum durum) is supported by bone of the Osseous part: proc. palatinus of os maxilla and os incisive + horizontal plate of os palatinum.
• The soft palate (Palatum molle or Velum palatinum) is the caudal part of the palate.
• The oral side is covered by a thick, cornified mucosa.
• Papilla incisiva: incisive papilla, which is an elevation of mucosa at the rostral end of the palatine raphe
• Rugae Palatinae: Palatine ridges that are paired, transverse ridges which progressively decrease in prominence
• Raphe Palati: The palatine raphe is the median line of junction where the halves of the palate meet.

Horse Palate

• Oral side is covered by a thick, cornified mucosa.
• Contains papilla incisiva, which is an elevation of mucosa at the rostral end of the palatine raphe.
• Palatine Ridges (Rugae palatinae): Paired transverse ridges that progressively decrease in prominence, with a number of ridges totaling 14-16.
• Palatine Raphe (Raphe palati): The median line where the halves of the palate join.

Ruminant Palate

• Contains a dental pad (Pulvinus dentalis), which is an elavated, cornified surface with a thick, cornified elevation.
• Also has 16-18 rugae palatinae with papillae directed caudally.
• The palatine ridges are indistinct in carnivores, with 9-10 ridges in dogs and 7-9 in cats.

Palatum Molle

• The palatum molle, or soft palate, is the caudal continuation of the hard palate.
• It is a musculomucosal fold (a flap) that attaches rostrally to the palatine skeleton while contouring with the tongue’s root when in repose.

Tongue (Lingua or Glossa)

• The tongue is located on the ventral part of the oral cavity
• It consists of striated musculature, connective and adipose tissue, some glands, and is covered by a thick mucous membrane.
• Intrinsic muscles include Fibrae longitudinales superficiales et profundae(eq), Fibrae transversae, and Fibrae perpendiculares

Lingual Papillae

• The mucous membrane presents various papillae, named according to their shape/function.
• Mechanical papillae provide a rough surface for food manipulation.
• Gustatory papillae contain taste buds to bear taste.
• The filiform papillae are absent in equines, while conical papillae (papillae conicae) and lenticular papillae (papillae lentiformes) are present.
• Gustatory papillae include fungiform, vallate, and foliate papillae

Tongue Sections

• Radix linguae: The tongue’s root, connecting to the hyoid bone.
• Corpus linguae: The body of the tongue; dorsum linguae describes the dorsal part opposite the palate, attached to the oral floor by the frenulum linguae.
• Apex linguae: The tip, the free rostral portion of the tongue

Ruminant Tongues

• They feature a torus linguae on the caudal part of the dorsum, giving it a firm, plump feel.
• A deep pit called Fossa linguae is rostral to the torus.
• Ruminants have filiform papillae on the dorsum rostral to the fosa and numerous fungiform papillae along the edges of the apex.

Horse Tongues

• The horse tongue is long, narrow, and has prominent lateral surfaces.
• It has a dorsum thats elevated with a slender bar of cartilage known as cartilago dorsi linguae.
• Its apex is long and spatular.
• Horses have fungiform and vallate papillae (one pair). They also have foliate papillae (one pair) and a single, well-developed lingual frenulum.

Pig Tongues

• Pig tongues have a narrow and low dorsum, a long and pointed apex, and a double lingual frenulum.
• They contain filiform and fungiform papillae that are on the dorsal and lateral surface. They also contain vallate papillae in a pair at the body/root junction, and Foliate papillae (in a pair).

Dog Tongues

• Canine tongues are mobile with a wide and flat apex and a lyssa within the apex ventral surface. Borders are sharp.
• There is a Sulcus medianus linguae which is a median sulcus.
• Canine tongues have soft filiform papillae, fungiform papillae, 2-3 pairs of vallate papillae, and extremely small foliate papillae in a pair.
• Lyssa: Medial rodlike structure in submucosa within the apex ventral surface, consists of adipose tissue, skeletal muscle, and some cartilage
• Sublingual contains the recessus sublingualis lateralis, the caruncula sublingualis, frenulum linguae.

Cat Tongues

• Feline tongues have caudally directed, hooklike filiform papillae used for eating and grooming.
• Contains 2-3 pairs of vallate papillae and fungiform papillae.

Caruncula Sublingualis

• The caruncula sublingualis is a flattened projection on either side of the frenulum in most species, but is absent in pigs.
• Horses have a caruncular.

Sublingual Floor

• It is symmetrical and extends between the tongue and the mandible on each side.

Tooth Anatomy

• Corona Dentis: The visible part that projects from the gingiva or gums.
• Cervix Dentis: The constricted area between the crown and root of the tooth.
• Radix Dentis: The root of the tooth, concealed by gingiva and the alveolus.
• The radix dentis is not covered by enamel teeth consist of enamelum, dentinum, cementum and pulpa dentis.

Dental Surfaces

• Facies Mesialis: The surface facing the midline of the dental arch.
• Facies Distalis: The surface facing away from the midline.
• Facies Contactus:The surface where adjacent teeth meet.
• Facies lingualis (toward tongue).
• Facies vestibularis (labial (lips) or buccal (cheeks)).
• Facies Occlusalis: Chewing surface.

Diphylodont Dentition

• Teeth are replaced including Dentes decidui (deciduous teeth) and Dentes permanentes (permanent teeth)
• Teeth types consist of incisors (dentes incisivi), canines (dentes canini), premolares (dentes premolares), and molares (dentes molares).
• A dental formula describes dentition by indicating tooth type and number on one upper and lower arcade side; x2 gives total number.

Dental Formulas

• Pig (Dentes, su= 44): I3/3 C1/1 P4/4 M3/3
• Dog (Dentes, ca = 42): I3/3 C1/1 P4/4 M2/3, with upper P4 and lower M1 being dentes sectorii for shearing flesh and bone.
• Cat (Dentes,fe = 30): I3/3 C1/1 P3/2 M1/1. Upper P4 and lower M1 are the sectoral or carnassial teeth.
• Horse (Dentes,eq = 40 (36)): I3/3 C1(0)/1(0) P3/3 M3/3. Canine teeth are usually absent or rudimentary in female horses. Occasionally, a rudimentary upper P1 appears as a wolf tooth (dens lupinus).
• Ruminants (Dentes, Ru = 32): I0/4 C0/0 P3/3 M3/3. They have a dental pad (Pulvinus dentalis) and a wide gap.

Small Salivary Glands (gll. salivariae minores)

• Small salivary glands provide moisture in the location they are found and include: labial (gll. labiales), buccal (gll. buccales), and zygomatic glands.
• The zygomatic glands are found in carnivores (gl. zygomatica); molar in cat (gll. malares); hard palatine (gll. palatinae) and lingual (gll. linguales)

Large Salivary Glands (gll. salivariae majores)

• They are large glands located at a distance from the oral cavity with long excretory ducts that end inside the oral cavity.
• Include the Parotid (gl. parotis), Mandibular (gl. mandibularis), and Sublingual glands (gll. sublinguales).
• The sublingual glands are of two types.
  • Gl.sublingualis monostomatica: Single duct.
  • Gl.sublingualis polystomatica: Multiple ducts.

Parotid Gland

• Located at the head and neck junction, ventral to the auricular cartilage in the retromandibular fossa.
• It is well-developed in herbivores.
• Its duct (Ductus parotideus) opens into the oral vestibule on a papilla top opposite different cheek teeth.
• Dog: upper 3rd
• Horse: 3rd
• Pig, small Ruminants: 3rd-4th
• Ox: 5th

Mandibular Gland

• This gland is close to the jaw angle.
• It is partially covered by the gl. parotis. It bigger in ruminants than in dogs or cats.
• Its duct (Ductus mandibularis) opens at the carunculus sublingualis.

Sublingual Glands

• Gl.sublingualis monostomatica lays under the mucosa of the lateral sublingual recess and lateral tongue surface.
• Its duct, the Ductus sublingualis major, opens at the Caruncula sublingualis.
• Gl.sublingualis polystomatica is located more rostrally and has Ductus sublingualis minores.

Examples

• Ox: Its Ductus parotideus lies opposite the upper M2. It's sublingual glands open on a fold in the Recesus sublingualis lateralis.
• Horse: Its Ductas parotideus lies opposite the P3 and has sublingualis polystomatica glands that open on the recesus sublingualis.
• Pig: Its Ductas parotideus lies opposite P3 and has sublingualis polystomatica that open on the recesus sublingualis. The ductus sublingualis major opens near the lingual frenulum.
• Dog: The gl. zygomatica drains at 1M.

Pharynx

• A funnel-shaped musculo-membranous chamber common to digestive and respiratory tracts.
• The tunica mucosa has respiratory and digestive regions with different epitheliums,

Pharyngeal Cavity (Cavum pharyngis)

• Includes the Pars nasalis pharingis (dorsal to the soft palate), Pars oralis pharingis (ventral to the soft palate), and Pars laryngea pharingis (dorsal to the larynx and leading into the esophagus).

Cavum Pharyngis Openings

• The cavum pharyngis has 7 openings: paired choanae, paired auditory tube openings, an opening to the oral cavity and the oropharynx, an opening to the larynx and the esophagus.

Isthmus of Faucium

• This divides the oral cavity and can only be seen during swallowing.
• The orifice is between the Cavum oris proprius and Pars opralis pharyngis
• The orifice is bounded by the palatoglossal arch, soft palate, and tongue root.

Palatoglossal Arch

• This is a symmetrical ridge or fold of mucosa extending from the soft palate to the tongue to mark the boundary between mouth and pharynx.

Avian Anatomy

• The mouth of poultry lacks lips and teeth, relying on the beak edges for function with a horny beak varies among species.
• The tongue is small, triangular or U-shaped, rigid, and inflexible.
• Tongues of ducks/geese tongues have have papillae that create grooves to sift food from water.
• Poultry have no soft palate, so oropharynx - a combined cavity from beak to esophagus .