Structure and function of the oral cavity 1: The mouth - lips, cheeks, and palate

The Alimentary Tract/Canal

The passage (transport, physical processing and storage), from the Mouth to the Anus.

The Accessory Organs

the teeth, tongue, salivary glands, liver, gall bladder, pancreas and the anal sacs.

The mouth (Os/Oris): Rima oris /Oral fissure

the opening; Lips form the rim of the mouth

Ensures proper closure of the rima oris/oral fissure

Sucking milk in the young, Prevents loss of saliva and food while chewing

Angle of the mouth/oral commissure

Point where the upper and lower lips meet…

The Lips (labia oris)

Skin - Keratinization

Supported by Orbicularis oris m. a circular muscle and connective Tissue

Mucosa - Labial glands; minor salivary glands on the oral surface

The cheeks (buccae)

Form the caudo-lateral boundary of the oral cavity

Buccinator m. forms the major bulk

Inner mucosa and submucosa; Buccal glands – Minor salivary glands

Cheeks differences in species

Nerve supply

Sensory innervation – maxillary and mandibular branches of the trigeminal nerve (CN V)

Motor Innervation – Facial nerve (muscles of fascial expression)

Facial nerve supply

Blood Supply to the lips and cheeks

Facial artery: Superior labial and Angularis oris

Maxillary artery: Inferior alveolar – mental branches, Infraorbital – lateral nasal a.

Blood supply in the face

The oral cavity boundaries

Hard and soft palate – Roof

The Mylohyoideus muscles – floor

Lips and Cheeks – Walls

Rostral limit – Rima oris

Caudal limit – Palatoglossal arch

The oral cavity

The vestibule (of the mouth); Space outside the dental rows (arcades)

The oral cavity proper; Space inside the dental rows (arcades)

Organs: The tongue and teeth, Openings of the Salivary glands

Hard palate (palatum durum)

Rostral bony portion

Incisive, maxillary, and palatine bones

Rugae -Transverse ridges (Palatine rugae)

Incisive papilla

opening of the incisive ducts on both sides – ducts of the vomeronasal organ

Hard palate of the horse

The mucosa of the hard palate is thick, particularly in its most rostral part, and incorporates a very generous venous plexus,

may become engorged(lampas) at the time of tooth replacement when it may project above the occlusal surfaces of the neighboring teeth

Anatomy of the hard palate of the horse

Soft palate (palatum molle or velum palatinum)

Caudal membranous portion formed by muscles and connective tissue

Relation with epiglottis/epiglottic cartilage - Normally lies slightly over the epiglottis -

allowing continuous respiration

Soft palate in horses

Below the epiglottic cartilage in the horse – Obligatory nasal breather

Parts of the soft palate

Palatoglossal arch

Palatopharyngeal arch

Palatine tonsils

Palatine (Salivary) glands

Functions of the soft palate

Respiration – relaxed

Swallowing/vomiting – must be lifted

Anatomy of the soft palate

Continued anatomy of the soft palate

Muscles of the soft palate

Palatine muscles

Tensor veli palatini muscles

Levator veli palatini muscles

Palatopharyngeus muscles

Palatinus m.

Anatomy of soft palate muscles

Motor innervation of the soft palate

Branches of the Vagus nerve- CN X via Pharyngeal plexus

Tensor veli palatini – Mandibular br. Trigeminal (CN V)

Sensory innervation of the soft palate

Major and Minor Palatine (Maxillary division of the trigeminal nerve)

Glossopharyngeal nerve CN –IX

Cleft Palate & / Cleft lip

Blood vessels to consider while cleft palate repair

General features of the oral mucosa

Stratified squamous epithelium (SSE)

Dog, Cat and Pig – Non keratinized

Ruminant and horse – Keratinized

Lamina propria and submucosa is usually intermixed in the oral region(Muscularis mucosae is absent)

Mixed salivary glands and skeletal muscles

The Lip

Outer – Cutaneous/Skin

Middle - Orbicularis oris muscle

Inner – Oral, Stratified squamous epithelium

Ruminant and Horses – Keratinized

Seromucous (Mixed) labial (salivary) glands

TS through the lip, Dog/Cat

1. Mucocutaneous junction

2. Stratifies squamous epithelium (SSE) - keratinized

3. Keratin layer of SSE, 4. hair follicle(cutaneous side)

5. sebaceous gland

6. Skeletal muscle (orbicularis oris)

7, Seromucous labial salivary glands

8. duct of the glands

1. Sinus Hair,

2. Hair follicles and glands in the outer skin,

3. Subcutis

4. Stratified Squamous Epith.

5. Lamina propria and Submucosa

6. Buccinator Muscle

The buccal papillae of the sheep and Cross-section of the cheek (Sheep). The buccal papillae: Keratinized stratified squamous epithelium

The Hard palate tissues

Keratinized Stratified squamous epithelium

Abundant connective tissue in the submucosa

CT Papillae projecting into the epithelial layer

Salivary gland in the caudal portion only

The mucosa of the hard palate has several ridges that are covered by keratinized

stratified squamous epithelium (e). Bone of the hard palate (not shown) is located

deep to the connective tissue (ct) of the propria- submucosa that underlies the

epithelium. Hard palate, cat

Soft palate histology species differences

Soft palate of cat showing oropharyngeal part lined by stratified squamous epithelial non keratinized (A) rested on thick layer of submucosa (B) with heavy layer of salivary glands (Blue arrow)

Buprenorphine

Pain relief/sedative, Effective in cats, oral spray/drops

Administration of allergy shots in Small animals

Sub-lingual Immunotherapy(SLIT)

Detomidine

pain relief/sedation

It has been described in horses and calves