Overview
The cat mandible is made of two hemimandibles joined rostrally by the mandibular symphysis, a fibrous joint that never fuses. Each half has a horizontal body, holding the teeth, and a vertical ramus, where the masticatory muscles insert and which articulates with the skull. It is short and sturdy, built for a strong bite and for cutting meat rather than grinding.
Key features
- Body (corpus mandibulae): holds three incisors, the canine, two premolars (P3 and P4, 307–308 and 407–408 in the modified Triadan system) and one molar. The permanent dental formula of the cat is 2 × (I 3/3, C 1/1, P 3/2, M 1/1) = 30 teeth.
- Lower first molar (309/409): the lower carnassial tooth; its cutting edge works against the upper fourth premolar.
- Mental foramina: on the lateral surface of the body, exit of the mental nerve.
- Mandibular foramen: on the medial surface of the ramus, entry of the inferior alveolar nerve (mandibular nerve block).
- Coronoid process: tall and wide, insertion of the temporalis, lodged in the temporal fossa.
- Masseteric fossa: deep depression on the lateral surface of the ramus for the masseter.
- Condylar process: elongated transversely; it fits in the mandibular fossa of the temporal bone and restricts movement almost to a hinge, with very little side-to-side shift.
- Angular process: caudal projection where the masseter and medial pterygoid insert.
Clinical relevance
- Symphyseal separation: the most common mandibular injury of the cat, typical of high-rise falls and road accidents. It is stabilised with a cerclage wire around both hemimandibles.
- Mandibular fractures: of the body and ramus, and pathological fractures in bone weakened by periodontal disease.
- Tooth resorption: very common in adult cats; the mandibular third premolars (307/407) are the most frequently affected teeth. Diagnosis needs intraoral dental radiographs.
- Feline chronic gingivostomatitis: severe inflammation of the gingiva and the caudal oral mucosa; it often requires multiple extractions.
- Squamous cell carcinoma: the most common malignant oral tumour of the cat; it invades and destroys mandibular bone.
In this model the mandible comes from a structured-light scan of a domestic cat specimen (RISD Nature Lab).