Digestive System Anatomy: Mouth & Oral Cavity

Digestive System Anatomy of Domestic Animals and Poultry

• Focus is on the mouth, oral cavity (including accessory structures and salivary glands), and pharynx.

Mouth (Os s. Stoma)

• Includes the lips (Labia oris), oral cavity (Cavum oris), accessory structures (teeth, palate, tongue), and salivary glands (Gll. salivariae).

Lips (Labia oris)

• Composed of skin, muscle, tendon, glands, and oral mucosa.
• The upper and lower lips referred to as Labium superius et inferius.
• Rima oris defines the mouth opening, the slit between the lips.
• Commissura labiorum is where the two lips meet.
• Bucca is the cheek area, including the buccinator muscle, salivary glands, and loose mucosa.
• Horse (eq) lips are highly mobile with a large upper lip covered by fine, tactile hair and act as a prehensile organ for collecting food.
• Cow (bo) features a nasolabial plate (planum nasolabiale), which is a thick, modified skin area.
• Carnivores (Car) and small ruminants (cap;ov) have a medial groove, known as the philtrum, in the labium superius.
• Papillae labiales are present on the margin of the lower lip, especially in (ca) species.
• Pig (su) has a rostral plate or disc (planum rostrale), a fused labium superius and rostrum, that is not very mobile and covers the shorter, pointed lower lip.

Oral Cavity (Cavum oris)

• The oral cavity consists of the vestibule and the proper oral cavity.

Vestibule (Vestibulum oris)

• Labial vestibule (vestibulum labiale) = the space between the teeth and lips.
• Buccal vestibule (vestibulum buccale) = the space between the teeth and cheeks.
• In ruminants (Ru), the inner lip and cheek surfaces feature large, backward-pointing papillae, most prominent towards the mouth's corners and include papillae labiales and buccales.

Proper Oral Cavity (Cavum oris proprium)

• Situated within the dental arc and ends caudally at the Arcus palatoglossus.
• Contains palate (palatum), teeth (dentes), tongue (lingua) as well as salivary glands.
• Lined with a stratified squamous epithelium containing ducts from submucosal glands and mixed glands, generally pink or pigmented with melanin.
• Gum (gingiva) is modified mucous attached to teeth and alveolar bone

Palate

• Serves as a partly osseous, partly soft tissue partition separating the digestive and respiratory passages in the head.

Hard Palate (Palatum durum)

• Supported by bone that includes the proc. palatinus of os maxilla and os incisive, as well as the horizontal plate of os palatinum.
• The oral side is characterized by thick, cornified mucosa.
• Papilla incisiva: Incisive papilla, elevation of mucosa rostral end of palatine raphe.
• Rugae palatinae: Palatine ridges (paired) transverse ridges which progressively decrease in prominence.
  • Horses have 14-16 palatine ridges.
• Raphe palati: Palatine raphe, the median line of the junction halves of the palate.

Palatum durum variations

• Cow (bo): Has a dental pad (pulvinus dentalis instead of incisors.
  • Has 16-18 rugae palatinae with caudally directed papillae.
• Pig (su): Has 23-25 rugae palatinae.
• Carnivores: Have indistinct palatine raphe.
  • dogs have 9-10 palatine ridges present whereas cats (fe) have 7-9 palatine ridges on their hard palate.

Soft Palate (Palatum molle/Velum palatinum)

• Forms as a continuation of the hard palate.
• Is a musculomucosal fold attached rostrally to the palatine skeleton contours the tongue root in repose.

Tongue (Lingua/glossa)

• Ventral part of oral cavity and comprises striated musculature, connective and adipose tissue, some glands, and a thick mucous membrane.
• The lingualis proprius muscle (intrinsic).
  • Fibrae longitudinales superficiales et profundae(eq)
  • Fibrae transversae
  • Fibrae perpendicula

Lingual Papillae (Papillae linguales)

• The dorsal surface presents numerous papillae classified by shape and function.
• Mechanical papillae includes filiform, conical, and lenticular papillae.
  • Filiform papillae are Absent in eq
• Gustatory papillae bear taste buds and have sensory receptor cells.
  • Includes fungiform, vallate, and foliate papillae.
    • Foliate papillae are Absent in Ru

Lingua Anatomy

• Radix linguae: The tongue's root attached to the hyoid bone.
• Corpus linguae: The body of the tongue, with the dorsum linguae opposite the palate, attached to the oral floor via the frenulum linguae.
• Apex linguae: The tip, free and rostral.

Ruminant Tongue (Lingua, Ru)

• Distinguished featuring a Torus linguae in the caudal part of its dorsum, forming a large prominence, and is firm to touch.
• Fossa linguae: A deep pit rostral to the torus.
  • Has filiform papillae along the dorsum rostral to the fosa (+p.conice+p. lenticular)
• Has Fungiform papillae along the edges of the tip.
• Vallate papillae: Features 8-17 on each side in ox, 18-24 in sheep and 12-18 in goat.

Horse Tongue (Lingua, eq)

• Tongues of horses are long, narrow, with tall lateral surfaces and an elevated dorsum.
• Includes Long, narrow, tall lateral surfaces.
• Has a apex that is long, spatular in front.
• Presents with cartilago dorsi linguae + a slender bar of cartilage.
• Contains a large, single, lingual frenulum
• Includes p. fungiformes, p. vallatae, p. foliatae

Pig Tongue (Lingua, su)

• Is narrow with low dorsum and long, pointed apex.
• Has a double lingual frenulum.
• Shows the presence of p. filiformes, p. fungiformes, p. vallatae on the tongue and (4] p. foliatae

Dog Tongue (Lingua, ca)

• Very mobile tongue, with wide and flat apex.
• borders – sharpand contains lyssa within the apex ventral surface.
• Features a median sulcus.
• Types of papillae: p. filiformes – soft ; p. fungiformes , p. vallatae and p. foliatae

Lyssa

• Rod-like structure is embedded within the tongue.
• Consists of adipose tissue, skeletal muscle with cartilage.

Sublingual Structures

• Sublingual floor area includes:
  • Recessus sublingualis lateralis (lateral sublingual recess).
  • Caruncula sunlingualis (caruncula sublingualis).
  • Frenulum linguae.
• The caruncula sublingualis is absent in pigs.

Teeth

Tooth anatomy terminology

• Corona dentis: The free part projecting from gingiva.
• Cervix dentis: The constriction between crown and root.
• Radix dentis: The part is concealed by gingiva and alveolus that is uncovered by enamel.
  • Gums (gingiva).
• Contains a dentin centre, gingiva. bone. Cementum, a peridontal membrane, and nerves and blood vessels.
• Facies mesialis
• Facies occlusalis, vestibularis
• Facies distalis

Types of Dentition/Teeth (Dentes)

• Dentes decidui
• Dentes permanentes

Tooth Type

• Incisors – dentes incisivi (I)
• Canines – dentes canini (C)
• Premolars – dentes premolares (P)
• Molars – dentes molares (M)

Dental Formula

• Representates is followed by the number of such teeth on one side of the upper and lower arcade.
• X2 = total number

Variations in Different Animals.

• Pig (Dentes, su= 44): I 3/3 C 1/1 P 4/4 M 3/3
• Dog (Dentes, ca = 42): I 3/3 C 1/1 P 4/4 M 2/3 - Upper P4 and lower M1 → dentes sectorii
• Cat (Dentes,fe = 30): I 3/3 C 1/1 P 3/2 M 1/1 - Upper P4 and lower M1 is sectorial/carnassial
• Horse (Dentes,eq = 40 (36)): I 3/3 C 1(0)/1(0) P 3/3 M 3/3 - Usually absent or rudimentary in female horses.
• Ruminants (Dentes, Ru = 32): I 0/4 C 0/0 P 3/3 M 3/3

Salivary Glands

Small Salivary Glands (gll. salivariae minores)

• Located in the oral cavity and provide moisture.
  • Labial (gll. labiales).
  • Buccal (gll. buccales).
  • Zygomatic in carnivores (gl. zygomatica).
  • Molar in cat (gll. malares).
  • Hard palatine (gll. palatinae).
  • Lingual (gll. linguales).

Large Salivary Glands (gll. salivariae majores)

• Located in distance from the cavity.
  • Parotid (gl. parotis)
  • Mandibular (gl. mandibularis)
  • Sublingual glands (gll. sublinguales) :
    • gl.sublingualis monostomatica
    • gl.sublingualis polystomatica

Parotid Gland (gl. parotis) variations

• Dog → opposite upper 3rd cheek tooth.
• Horse→ 3 rd;
• Pig, small Ru → 3rd-4th;
• Ox → 5th.

Ductus mandibularis variations

• Ox and horse: Is located close to the angle of the jaw.
• parotis; is slightly bigger than the late in dog, cat, but considerably large in Ru.

Sublingual Gland Classification

• gl.sublingualis monostomatica, Ductus sublingualis major →Caruncula sublingualis.
• gl.sublingualis polystomatica: ductus sublingualis minores ,on a longitudinal fold in the Recesus sublingualis lateralis

Pharynx

• A funnel-shaped musculo-membranous chamber is common to the digestive and respiratory tracts.
• tubular organ
• Tunica mucosa
  • Respiratory region – pseudostratified columnar epithelium
  • Digestive region – stratified squamous epithelium

Pharyngeal Cavity (Cavum pharyngis)

• Pars nasalis pharingis: Dorsal to the soft palate.
• Pars oralis pharingis: Ventral to the soft palate.
• Pars laryngea pharingis: Dorsal to the larynx and leading into the esophagus.

Cavum pharyngis

• Consists of 7 openings including:
  • Choanae (2).
  • Ostium pharyngeum tubae auditivae (2).
  • Oropharynx.
  • Laryngopharynx.

Isthmus of Faucium

• Divides the oral cavity and the pharynx, bounded by the palatoglossal arch, soft palate, and tongue root.

Palatoglossal arch

• A symmetrical ridge that is a fold of the mucosa extending from the soft palate to the tongue. This boundary lies in between the mouth and the pharynx.

Intrapharyngeal osmium, Ostium intrapharyngeum and Palatopharyngeal arch

• Is formed by the free border of the soft palate and the right and left Arcus palatopharyngeus and connects the Pars nasalis and pars laryngea pharyngis

Avian

Anatomical Peculiarities of Poultry (chicken; duck; goose; turkey)

Mouth

• Features lack in teeth are absent, thus their are used for prehension.
• Includes a horny beak that caries a large amount in from and a hard.
• Tongues that are small and riggid and U or triangular Shaped.
• Dorsal suface presents as an array of papillae for use in sifting food from water

Oropharnyx

• Is joined cavity that combines to the esophagus, no soft palates
• Includes palatine ridges, salivary glands and papillae

An overview of the anatomy of the digestive system in domestic animals and poultry, focusing on the mouth and oral cavity. Covers the lips, oral cavity, accessory structures like teeth and tongue, and salivary glands. Specific features of lips in horses, cows, and carnivores are highlighted.