Overview
The cat skull is divided into the braincase (neurocranium), which protects the brain, and the facial skeleton (viscerocranium), which forms the nose, the orbits and the mouth. Compared with the dog it is short and rounded, with a brief face and a proportionally large braincase. Breed variation is smaller than in the dog, but brachycephalic breeds (Persian, Exotic Shorthair, Himalayan) have a markedly shortened face.
Key features
- Orbits: very large and directed rostrally, giving a wide binocular field of view. The orbital rim is incomplete: the zygomatic process of the frontal bone and the frontal process of the zygomatic bone almost meet, and the orbital ligament closes the gap.
- Zygomatic arches: wide and strongly curved. With the external sagittal crest and the temporal lines they give origin and insertion to the temporalis and masseter, powerful muscles in a predator.
- Occipital bone: carries the foramen magnum and the occipital condyles, which articulate with the atlas.
- Tympanic bulla (bulla tympanica): large and rounded. In the cat a bony septum (septum bullae) divides it into a large ventromedial compartment and a small dorsolateral one, joined by a narrow opening.
- Maxilla and incisive bone: hold the upper teeth. The infraorbital foramen is the exit of a very short infraorbital canal.
- Upper teeth: three incisors, one canine, three premolars (P2–P4) and one tiny molar on each side. The upper fourth premolar (108/208 in the modified Triadan system) is the upper carnassial tooth, which shears like scissors against the lower first molar.
- Temporomandibular joint: the mandibular fossa of the temporal bone, limited caudally by the retroarticular process, holds the mandibular condyle and allows almost only hinge movement.
Clinical relevance
- High-rise syndrome: cats falling from several floors strike the chin and face; separation of the mandibular symphysis, fractures of the hard palate and dental injuries are typical.
- Middle ear: nasopharyngeal polyps of young cats arise from the middle ear or the auditory tube. Ventral bulla osteotomy must open both compartments; the sympathetic fibres running through the middle ear explain Horner's syndrome after surgery.
- Dental nerve blocks: because the infraorbital canal is so short, a needle advanced into it can reach the orbit and puncture the globe.
- Brachycephaly: stenotic nares, angled nasolacrimal ducts (epiphora) and dental malocclusions.
- Dental disease: tooth resorption and feline chronic gingivostomatitis also affect the teeth and gingiva of the upper jaw.
In this model the skull comes from a structured-light scan of a domestic cat specimen (RISD Nature Lab).