Digestive System Anatomy: Lips and Oral Cavity

Digestive System Anatomy - Domestic Animals and Poultry

• The mouth and oral cavity feature accessory structures and salivary glands
• The pharynx is also an important structure in the digestive anatomy

Lips (Labia Oris)

• Lips consist of skin, muscle, tendon, glands, and oral mucosa
• Labium superius et inferius refers to the upper and lower lips
• Rima oris is the mouth opening, or the slit between the lips
• Commissura labiorum is where the two lips meet
• Bucca refers to the cheek

Lip Variations Among Animals

• Horse (eq): highly mobile lips with large upper lip covered in fine hair, acting as a sensitive tactile and prehensile organ
• Cow (bo): has a nasolabial plate (planum nasolabiale), which is a thick, modified skin
• Carnivores (Car) and small ruminants (cap;ov): feature a medial groove (philtrum) in the labium superius
• Papillae labiales are also located on the margin of the lower lip
• Pig (su): has a rostral plate (disc), called the planum rostrale, which includes the labium superius and rostrum but is not very mobile; the lower lip in pigs is pointed, shorter, and beneath the upper lip

Oral Cavity (Cavum Oris)

• Vestibule (Vestibulum oris):
• • Labial vestibule (vestibulum labiale) is the space between the teeth and lips
• • Buccal vestibule (vestibulum buccale) is the space between the teeth and cheeks
• Proper oral cavity (Cavum oris proprium):
• • The proper cavity is within the dental arches
• • It is limited caudally by the Arcus palatoglossus
• • Palate (palatum), teeth (dentes), tongue (lingua), and salivary glands are within

Vestibule Features in Ruminants

• Ru: inner surfaces of lips and cheeks feature large, backward-pointing papillae
• These papillae are most prominent toward the corners of the mouth; Papillae comprise labiales and buccales

Proper Oral Cavity

• Mucous membrane lining the oral cavity consists of stratified squamous epithelium
• Membranes are penetrated by ducts of submucosal glands
• Color is usually pink or has black pigmented areas
• Submucous membrane contains mixed glands
• Gum (gingiva) are modified mucous attached to the teeth and alveolar bone

Palate (Palatum)

• Palate is a partly osseous and partly soft tissue partition separating digestive and respiratory passages
• Hard palate (Palatum durum) is supported by bone
• Includes the osseous parts of the proc. palatinus of os maxilla and the os incisive + horizontal plate of os palatinum
• Soft palate (Palatum molle / Velum palatinum) is the caudal part of the palate

Hard Palate Features

• Oral side features thick, cornified mucosa
• Papilla incisiva:
• • Located at the rostral end of the palatine raphe
• • Contains the incisive papilla, which creates an elevation of mucosa
• Rugae palatinae:
• • Palatine ridges (paired)
• • Features transverse ridges that progressively decrease in prominence
• Horse: Number of ridges typically around 14 to 16
• Raphe palati:
• • Palatine raphe forming the median line of junction in the halves of the palate

Variations in Palatum Durum

• Cow (bo): dental pad with pulvinus dentalis
• Pig (su): has rugae palatinae numbering 23-25
• Carnivores (Car): indistinct palatine raphe; palatine ridges around 9-10 in dogs (ca) and 7-9 in cats (fe)

Soft Palate (Palatum Molle / Velum Palatinum)

• Forms a caudal continuation of the hard palate
• Acts as a musculomucosal fold (flap)
• Rostrally attached to the palatine skeleton
• In repose, it follows the contours of the root of the tongue

Tongue (Lingua / Glossa)

• Ventral part of the oral cavity
• Composed of striated musculature, connective and adipose tissue, some glands
• Thick mucous membrane externally
• Intrinsic muscles:
• • M. lingualis proprius
• • Fibrae longitudinales superficiales et profundae (eq)
• • Fibrae transversae
• • Fibrae perpendiculares

Lingual Papillae (Papillae Linguales)

• Mucous membrane on the dorsal surface presents numerous papillae
• Papillae are classified according to their shape and function

Mechanical Papillae

• Filiform papillae (papillae filiformes): absent in horse (eq)
• Conical papillae (papillae conicae)
• Lenticular papillae (papillae lentiformes

Gustatory Papillae

• Bear taste buds
• Fungiform papillae (papillae fungiformes)
• Vallate papillae (papillae vallatae)
• Foliate papillae (papillae foliatae): absent in ruminants (Ru)

Tongue Regions

• Radix linguae: the root
• • Connects to the hyoid bone
• Corpus linguae: the body
• • Dorsum linguae is the dorsal part opposite the palate
• • Connects by mucosal fold (frenulum linguae) to the oral floor
• Apex linguae: the tip
• • Free rostral portion

Tongue of Ruminants (Lingua, Ru)

• Torus linguae:
• • Caudal part of the dorsum is raised, forming large prominence
• • Ox: firm and plump
• Fossa linguae:
• • Acts as the deep pit rostral to the torus in cows (bo)
• Papillae
• • filiformes: on dorsum rostral to the fossa
• -fungiformes numerous along the edges of the apex
• • vallatae: 8-17 on each side in ox; 18-24 in sheep; 12-18 in goat
• Wide and large, double frenulum linguae

Tongue of the Horse (Lingua, eq)

• Features long, narrow, tall lateral surfaces with an elevated dorsum
• Contains a slender cartilage bar (cartilago dorsi linguae)
• Apex is long and spatular
• Contains p. fungiformes, p. vallatae (1 pair), p. foliatae (1 pair) and single, well developed lingual frenulum

Tongue of the Pig (Lingua, su)

• Narrow
• Low dorsum
• Long, pointed apex
• Double lingual frenulum
• p. filiformes, p. fungiformes covers over the dorsal, lateral surface, p. vallatae (1 pair) at the junction of body and root
• p. foliatae numbering one pair

Tongue of the Dog (Lingua, ca)

• Mobile with a wide, flat apex
• Contains lyssa within the apex ventral surface
• Sharp borders
• Sulcus medianus linguae is the tongue's median sulcus
• p. filiformes are soft with p. fungiformes that are 1mm in diameter
• p. vallatae number 2-3 pairs; p. foliatae number 1 pair and are extremely small

Lyssa

• Lyssa is the median rodlike structure in the submucosa within the apex ventral surface
• It includes adipose tissue, skeletal muscle, and some cartilage

Sublingual Floor

• Recessus sublingualis lateralis contains (b) recessus sublingualis lateralis, (d) caruncula sublingualis, (e) frenulum linguae

Cat Tongue (Lingua, fe)

• Papillae linguales:
• -p. filiformes caudally directed, hooklike and firm, used for for eating an grooming
• -p. fungiformes ~1mm in diameter and have very large taste buds
• -p. vallatae are present in 2-3 pairs

Caruncula Sublingualis

• Sublingual caruncle, is a flattened projection on either side of the frenulum, but more rostral
• • Absent in pig

Caruncular Fold

• Sublingualis lateral to frenulum linguae

Tooth Anatomy

• Corona dentis: free part projecting from gingivae
• Cervix dentis: constriction between crown and root
• Radix dentis: concealed by gingiva and alveolus
• • Not covered by enamel
• Gingiva with enamelum
• Dentium is the main substance, cementum is bone-like substance
• Pulpa dentis

Dental Surfaces

• Facies mesialis
• Facies occlusalis
• Facies contactus
• Facies distalis with facies lingualis, and facies vestibularis (labial & buccal)

Dentition

• Dentes decidui: deciduous teeth
• Dentes permanentes: permanent teeth
• Teeth develop differently in each region of the mouth; according to their use are grouped:
• • Incisors (dentes incisivi -I)
• • Canines (dentes canini -C)
• • Premolares (dentes premolares -P)
• • Molars (dentes molares -M)

Dental Formula

• Describes the number and classification of dentition for a species
• Uses abbreviation representing the tooth
• Shows the number of such teeth on one side of the upper and lower arcade which is then multiplied by two for the total number

Pig Dentition (su = 44)

• I 3/3, C 1/1, P 4/4, M 3/3

Dog Dentition (ca = 42)

• I 3/3, C 1/1, P 4/4, M 2/3
• Upper P4 and lower M1 are dentes sectorii for shearing flesh and bone

Cat Dentition (fe = 30)

• I 3/3, C 1/1, P 3/2, M 1/1
• Upper P4 and lower M1 are sectoral or carnassial and are dentes sectorii

Horse (eq = 40/36) Dentition

I 3/3 C 1(0)/1(0) P 3/3 M 3/3 Canine teeth (C) are usually absent or rudimentary in female horses, but occur in some mares

Horse Specializations

• Brown colored teeth
• Cement covers the entire tooth
• cement-filled infundibula i.e. cups of incisors - Infundibulum dentis
• Folding in M (upper) results in the formation of cement -filled folds of cheek teeth

Ruminant Dentition (Ru = 32)

I 0/4, C 0/0, P 3/3, M 3/3 Dentes are not present in the upper jaw Dental pad (pulvinus dentalis) The elevation is cornified upon the surface but pliant when compressed A wide gap or diastema separates the incisors from the cheek teeth row

Small Salivary Glands

• gll. salivariae minores located in the oral cavity
• Provide local 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 large and located in distance from the oral cavity
• Excretory ducts are long, ending in the oral cavity
• Parotid (gl. parotis)
• Mandibular (gl. mandibularis)
• Sublingual glands (gll. sublinguales)
• -gl.sublingualis monostomatica
• -gl.sublingualis polystomatica

Parotid Gland (gl. parotis)

• Located at the junction of the head and neck, ventral to the auricular cartilage in retromandibular fossa
• Is dorsally adjacent to the base of the ear and ventrally extends into the neck or into intermandibular space
• Especially well-developed in herbivores
• Ductus parotideus drains saliva:
• • Dog: Opposite upper third cheek tooth
• • Horse: Opposite third cheek tooth
• • Pag, small Ruminant: Opposite third to fourth tooth
• • Ox: Opposite fifth cheek tooth

Mandibular Gland (gl. mandibularis)

• Located close to the angle of the jaw
• Partially covered by the gl.parotis slightly bigger than in the dog, cat, but considerably larger in Ruminants
• Ductus mandibularis drains through carunculus sublingualis

Sublingual Glands

• Consists of gl.sublingualis monostomatica
• It lays under mucosa of the lateral sublingual recess and lateral surface of the tongue
• Ductus sublingualis major drains through the caruncula sublingualis

gl.sublingualis polystomatica

• Located more rostrally than gl.sublingualis monostomatica
• Ductus sublingualis minores drains saliva
• Opens through several smaller ducts
• Drains the longitudinal fold in the Recesus sublingualis lateralis

Ox (bo) Salivary Gland Locations

• gl. parotis: ductus parotideus drains opposite the upper molar 2 in bovine and Caprine/Ovine, ductus is opposite P3/4
• gl. mandibularis are 18-20 x 8-10 cm in size; ductus mandibularis drains saliva through the caruncula sublingualis

Horse (eq) Salivary Gland Locations

• gl. parotis: with ductus parotideus draining opposite the upper premolar 3
• gl. mandibularis glands 20-23 x 2-3.5 cm; with ductus mandibularis draining saliva through the caruncula sublinqualis
• gl.sublingualis polystomatica → ductus sublingualis minores - on a longitudinal fold in the recesus sublingualis lateralis
• gl.sublingualis monostomatica is absent in the horse

PHARYNX (Pharynx)

• Funnel-shaped, musculo-membranous chamber common to the digestive and respiratory tracts
• Tubular organ with tunica mucosa consisting of respiratory and digestive regions

Pharyngeal Cavity Regions

• 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)
• All connect to to Osmium interpharyngeum

Pharyngeal Openings Included

• Choanae (2)
• Ostium pharingeum tubae auditivae (2): opening to auditory tube
• Hard Palate
• Soft Palate
• Fauces
• Oropharynx and Laryngopharynx
• Tongue
• Aditus oesophageus
• Aditus laryngis

Isthmus of Faucium

• Divides the oral cavity from pharynx; except when swallowing
• Orifice between cavum oris proprius and pars opralis pharyngis
• Bounded by the palatoglossal arch, soft palate, and tongue root
• Palatoglossal arch: symmetrical ridge or fold of mucosa extending from the soft palate
• Extends to the tongue at the boundary between mouth and pharynx
• Intrapharyngeal ostium passage is between pars nasalis and pars laryngea pharyngis
• Formed by free border of the soft palate
• Palatopharyngeal arch is mucous-covered and extends from soft palate
• Ends at opening of the oesophagus

Anatomical Peculiarities of Poultry

• Lips and teeth are absent, functions are met by the edges of the beak
• Horny beak varies form amoung species; dependent on diet
• Tongue is small, triangular or U-shaped, rigid, inflexible
• Dorsal surface of the chicken tongue is smooth and pink with row of papillae near caudal attachment
• Ducks and geese have tongues fringed with papillae that fit loosely into grooves in the edges of the beak, which provides means of sifting food particles from water

Explore the anatomy of the digestive system in domestic animals and poultry, focusing on the mouth, oral cavity, and pharynx. Learn variations in lip structure across species like horses, cows, carnivores, and pigs. Understand key features such as the nasolabial plate and rostral plate.