external carotid arteries branch out into the maxillary arteries. They further supply the mandibular (inferior alveolar) arteries, which enter the mandibular foramina on the medial sides of the mandibles and then course rostrally in the mandibular canals, where they exit through the mental foramina. The maxillary arteries also give rise to the major palatine arteries, which anastomose with the infraorbital arteries. The infraorbital arteries exit at the infraorbital foramina to supply the rostral muzzle. The lingual artery, a branch of the external carotid artery, supplies the tongue and mucosa of the floor of the oral cavity. The mandibular canal contains the inferior alveolar artery, vein, and nerve (the neurovascular bundle).
Lymph from the oral cavity drains into the parotid, mandibular, lateral, and medial retropharyngeal, superficial, and deep cervical lymph nodes. The mandibular lymph nodes are located rostral to the mandibular salivary gland. They are not lobulated like the salivary gland and therefore can be distinguished from them. They, along with the parotid lymph nodes, drain the entire head. They are more superficially located than the parotid lymph nodes and therefore are more easily palpated.
1.7 Salivary Glands
The major salivary glands in the cat include the parotid, zygomatic, mandibular, and sublingual. The mandibular salivary gland is located caudal to the ramus of the mandible and ventral to the parotid gland. The sublingual salivary gland lies in close approximation to the rostral aspect of the mandibular gland.
Saliva from the parotid gland exits at a papilla in the alveolar mucosa, just caudal to the maxillary fourth premolar. Saliva from the zygomatic gland exits at a papilla in the alveolar mucosa near the maxillary first molar. Saliva from the mandibular and sublingual glands enters the oral cavity through the sublingual caruncles located ventral and rostral to the base of the tongue (Figure 1.4) (Illustration 1.1).
Cats have four molar salivary glands. The buccal molar glands empty into the oral cavity through several small ducts. The lingual molar glands are located in the membranous molar pad linguodistal to the mandibular first molar teeth (Figure 1.5).
Figure 1.4 Sublingual caruncles.
Illustration 1.1 Cat salivary glands.
Source: Image courtesy of Tamara Rees, Veterinary Information Network.
Figure 1.5 Membranous bulge linguodistal to the mandibular first molar tooth containing a minor salivary gland (lingual molar gland).
1.8 Periodontium
The term periodontium or periodontal apparatus is used to describe tissues that surround and support the teeth, including the gingiva, periodontal ligament, cementum, and alveolar bone.
Figure 1.6 Oral mucosa in a patient with gingivitis, periodontitis, and caudal mucositis.
1.9 Gingiva
The cat's oral cavity is lined with keratinized and nonkeratinized stratified squamous epithelium. Gingiva refers to the keratinized oral mucosa that covers the alveolar process and surrounds the cervical portion of the tooth crowns. Unlike the epithelial lining of the digestive tract, the gingiva does not have absorptive capacity but acts as a physiologic permeable barrier that protects underlying structures from the invasion of microorganisms and other foreign substances (Figure 1.6).
The gingival epithelium is composed of the following:
The oral epithelium, also called the outer gingival epithelium, is keratinized or parakeratinized and covers the oral surface of the attached gingiva and gingival papillae.
The sulcular epithelium is a nonkeratinized extension of the oral epithelium into the gingival sulcus. The bottom of the gingival sulcus in a periodontally healthy tooth should be slightly coronal to the cementoenamel junction.
The junctional epithelium attaches to enamel of the most apical portion of the crown by means of hemidesmosomes and lies at the floor of the sulcus, immediately coronal to or at the cementoenamel junction. The junctional epithelium and gingival connective tissue separate the periodontal ligament from the oral environment. The floor of the gingival sulcus is apically bounded by junctional epithelial cells.
1.9.1 Marginal Gingiva
Marginal gingiva is the most coronal (toward the crown) aspect of the gingiva that is not attached to the tooth but lies passively against it. When healthy, it appears coral‐pink and firm, with knife‐edged margins. Pigment may or may not be present. The space between the tooth and the marginal gingiva is the gingival sulcus (or crevice). The normal depth of the sulcus is less than 1 mm in cats.
1.9.2 Free Gingival Margin
The free gingival margin is the coronal edge of the marginal gingiva. Marginal gingiva is demarcated from the attached gingiva by the gingival groove, a slight depression on the gingiva corresponding to the normal sulcus depth (Figure 1.7a,b).
The healthy free gingival margin of premolars and molars lies 0.5–1 mm coronal to the cementoenamel junction, where root cementum meets the crown enamel.
Figure 1.7 (a) and (b) Gingival structures surrounding the left maxillary (a) and right mandibular (b) cheek teeth.
Figure 1.8 Compressed air from an air/water syringe exposing the normal 0.5 mm sulcus surrounding the left maxillary fourth premolar.
1.9.3
