Digestive System Anatomy: Mouth & Oral Cavity

Digestive System Anatomy of Domestic Animals and Poultry

• Focuses on the mouth, oral cavity with accessory structures, salivary glands, and the pharynx

Mouth (Os s. Stoma)

• The mouth connects to the lips, also known as labia oris
• The oral cavity is known as the cavum oris
• Accessory structures of the oral cavity include teeth (dentes), palate (palatum), tongue (lingua), and the salivary glands (gll. salivariae)
• In Equidae (eq), the lips are highly mobile, with a large upper lip covered in fine, tactile hair, and a prehensile organ for collecting food
• In Bovidae (bo), the labia oris includes a thick, modified skin known as planum nasolabiale
• In Carnivora (car) and small ruminants (cap;ov), the labium superius contain a medial groove known as philtrum
• A papillae labiales is located on the margin of the lower lip in Carnivora (ca)
• In Suidae (su), a rostral plate (disc) known as planum rostrale is present, with not very mobile lips where the lower lip is pointed and shorter, covered by the upper lip

Oral Cavity (Cavum Oris)

• Two parts: the vestibule (vestibulum oris) and the proper oral cavity (cavum oris proprium)
• Vestibule is divided into two parts: labial vestibule (space between teeth and lips), and buccal vestibule (space between teeth and cheeks)
• In ruminants (Ru), the inner surface of the lips and cheeks have large, backward-pointing papillae most prominent toward the corners
• The proper oral cavity is the space within the dental arc and limited caudally by the Arcus palatoglossus
• Palate (palatum), teeth (dentes), tongue (lingua) and salivary glands are within the cavum oris proprium
• Mucous membrane lining the oral cavity is stratified squamous epithelium, penetrated by the ducts of submucosal glands
• Lining color is usually pink or pigmented black and contains mixed mucous
• Gum (gingiva) is a modified mucous attached to the teeth and alveolar bone

Palate (Palatum)

• Is a partly osseous, partly soft tissue partition that separates the digestive and respiratory passages of the head
• Hard palate (palatum durum) is bone-supported
• Soft palate (palatum molle) is the caudal part of the palate, also referred to as velum palatinum
• Oral side of the hard palate surfaces is covered by thick, cornified mucosa
• In Equidae, the hard palate includes the papilla incisiva at the rostral end of palatine raphe and the rugae palatinae (palatine ridges) which decreases in prominence, and raphe palati - palatine raphe in the median line
• Horses usually have 14-16 palatine ridges
• In Bovidae the palatum durum consists of dental pad, Pulvinus dentalis and usually 16-18 rugae palatinae accompanied by papillae, directed caudally
• In Suidae the the rugae palatinae are = 23-25
• In Car the Palatine raphe is indistinct and Palatine ridges – ca: 9 -10; fe:7-9
• Soft palate (palatum molle) forms a caudal continuation of the hard palate
• Soft palate acts as a musculomucosal fold and is rostrally attached to the palatine skeleton, following the contours of the tongue's root

Tongue (Lingua or Glossa)

• Ventral part of the oral cavity containing striated musculature, connective tissue, adipose tissue, some glands and is lined with a thick mucous membrane
• M. lingualis proprius (intrinsic) contains fibrae longitudinales superficiales et profundae (eq), fibrae transversae, and fibrae perpendiculares
• Lingual papillae are named according to shape/function on the dorsal surface
• Mechanical papillae are filiform (absent in eq), conical [d], and lenticular
• Gustatory papillae bear taste buds with fungiform [c], vallate [f], and foliate (absent in Ru) papillae present
• Divided into three parts which includes the radix linguae, corpus linguae and apex linguae

Ruminant Tongue (Lingua, Ru)

• Torus linguae is on the caudal part of the dorsum and forms large prominence
• Ox possess a firm, tick and plump tongue
• Fossa linguae is a deep pit rostralto the torus
• Filiform (p. filiformes), vallate (p. vallatae) and fungiform (p. fungiformes) papillae are present

Horse Tongue (Lingua, eq)

• Long, narrow, and has tall lateral surfaces with elevated dorsum and slangier bar of cartilage described as cartilago dorsi linguae
• Is long and spatular in front
• Possess 3-types papillae includes: p. fungiformes, p. vallatae, and p. foliatae, long with single well developed lingual frenulum

Pig Tongue (Lingua, su)

• Narrow, the dorsum is low with long and pointed apex
• The lingual frenulum is double
• Papillae types includes: P. filiformes, P. fungiformes, P. vallatae, and P. foliatae

Dog Tongue (Lingua, ca)

• Very mobile with a wide, flat apex
• Includes lyssa within the apex ventral surface and sharp borders
• Characterized by Sulcus medianus linguae
• Has soft filiform papillae
• Fungiform papillae are 1mm in diamete
• Possess 2-3 pairs of vallate papillae and small foliate papillae

Other tongue traits

• Lyssa is a medial rod-like structure in the submucosa within the apex ventral surface, consisting of adipose tissue, skeletal muscle and some cartilage
• On the sublingual floor a recessus sublingualis lateralis, caruncula sublingualis and frenulum linguae is present in dogs
• On the cat tongue, papillae linguales include filiform (p. filiformes), vallate (p. vallate) and fungiformes (p. fungiformes)
• The palatine and sublingual glands are not consistent, and may vary amongst species
• Caruncula sublingualis found on the sublingual floor is absent in pigs and the caruncular fold is referred to as Plica sublingualis lateral

Salivary Glands

• Small salivary glands (gll. salivariae minores) are in the oral cavity, of local importance, provide moisture for the area in which they are found
• Types of small salivary glands includes : labial (gll. labiales), buccal (gll. buccales), and lingual (gll. linguales)
• Zygomatic salivary glands are found in carnivores with a molar salivary gland found in cats
• Hard palate salivary glands (gll. palatinae) can also be present
• Salivary glands are large and some are located some distance from the oral cavity
• Salivary glands excretory ducts are long and end with an entrance to the oral cavity Types of large salivary glands:
  • Parotid gland (gl. parotis)
  • Mandibular gland (gl. mandibularis)
  • Sublingual glands (gll. sublinguales)
  • gl.sublingualis monostomatica
  • gl.sublingualis polystomatica

Salivary Glands specific to certain species

• Parotid gland sits at the junction of the head and neck, Ventral to the auricular cartilage, in retromandibular fossa
• Very well-developed in herbivores includes the Ductus parotideus which opens into the oral vestibule at top of a small papilla
• Parotid duct locations by species: Dog (opposite upper 3rd cheek tooth), Horse (3rd), Pig, small Ru (3rd-4th, Ox (5th)
• Mandibular gland is located close to angle of jawis partially covered by the parotid and is large in ruminants especially
• Ductus mandibularis is a carunculus sublingualis
• Gll. Sublingualis monostomica in lateral sublingual recess with Ductus sublingualis major to Carduncula sublingualis
• Gll. sublingualis polystomatica located rostrally with longitudinal recesus sublingualis lateralis

Salivary Gland Locations by Species

• In ox, the Ductus parotideus located opposite M2, Ductus mandibularis ends in Caruncula sublingualis
• Horse: Ductus parotideus ends opposite P3, - Gll. sublingualis monostomatica are absent
• In pigs: . Ductus mandibularis near lingual frenulum
• Dog: Duct associated with 1M

Pharynx

• A funnel-shaped musculo-membranous chamber common to digestive and respiratory tracts
• Is a tubular organ with the tunica mucosa
• Respiratory region is pseudostratified columnar epithelium.
• Digestive region is stratified squamous epithelium
• Contains gll. pharyngeae

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)

• Contains Ostium interpharyngeum

• Cavum pharyngis consists of 7 openings, choanae, Ostium pharingeum tubae auditivae, fauces, and Isthmus faucium

Isthmus of Faucium - Isthmus faucium

• Divides the oral cavity and the pharynx, except when swallowing
• Is the orifice between the Cavum oris proprius and Pars opralis pharyngis, bounded by the palatoglossal arch, soft palate, and tongue root includes Palatoglossal arch - Arcus palatoglossus
• Contains Intrapharyngeal ostium - Ostium intrapharyngeum (passage between).
• Consists of soft palate around the Ostium intrapharyngeum, with Arcus palatopharyngeus

Poultry (chicken; duck; goose; turkey)

• Mouth: lips and teeth absent
• Horny beak varies tremendously in form among species, according to diet
• Tongue : is small, triangular or U-shaped, rigid, inflexible
• Dorsal surface of the chicken tongue -smooth and pink + a row of large papillae near the caudal attachment
• tongues are fringed with papillae that fit loosely into grooves in the edges of the beak, which provides a means of sifting food particles from water.
• soft palate absent
• opharynx - is combined cavity from beak to the esophagus

Anatomy of the mouth and oral cavity in domestic animals and poultry. Focuses on the lips, oral cavity, and its accessory structures such as teeth, palate, tongue, and salivary glands across species like Equidae, Bovidae, Carnivora, and Suidae.