Overview
The bovine 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. It is long, wide and heavy, with a braincase that is small relative to the size of the head. Its most typical feature is the huge frontal bone (os frontale), which covers the whole dorsal surface back to the poll and pushes the parietal bones onto the caudal surface of the skull.
Frontal region and horns
- Intercornual protuberance (protuberantia intercornualis): transverse ridge between the horns that forms the poll; it is the highest point of the skull.
- Cornual process (processus cornualis): bony extension of the frontal bone that forms the horn core, covered by the corium and the horny sheath. Its shape and size vary with breed, sex and age; it is absent in polled breeds such as the Aberdeen Angus.
- Frontal sinus (sinus frontalis): very large; in the adult it surrounds the cranial cavity dorsally and caudally and extends into the cornual process.
- Temporal line (linea temporalis): ridge running from the orbit to the base of the horn that separates the frontal surface from the temporal fossa, which in cattle lies on the lateral side of the skull.
Face and teeth
- Orbits: directed laterally, with a complete bony orbital rim.
- Facial tuber (tuber faciale): prominence on the lateral surface of the maxilla, rostral to the orbit and dorsal to the cheek teeth; origin of the masseter muscle.
- Incisive bone (os incisivum): has no alveoli. Instead of upper incisors there is a dental pad (pulvinus dentalis), a horny plate against which the lower incisors press the grass that the tongue wraps around and tears off.
- Upper teeth: no incisors or canines; three premolars (P2–P4) and three molars on each side. They are selenodont, with crescent-shaped enamel ridges on the occlusal surface. The upper arcades are set wider apart than the lower ones (anisognathism), so the animal chews on one side at a time.
- Adult dental formula: 2 × (I 0/3, C 0/1, P 3/3, M 3/3) = 32.
- Temporomandibular joint: allows the wide side-to-side movements of chewing and rumination.
Clinical relevance
- Dehorning: in older animals the cut opens the frontal sinus that fills the horn core; for this reason disbudding of young calves, before the core becomes pneumatised, is preferred.
- Frontal sinusitis: a complication of dehorning or horn fractures; it causes nasal discharge, often unilateral, and pain on percussion over the sinus.
- Cornual nerve block: the cornual nerve runs along the temporal line, between the lateral canthus of the eye and the base of the horn; it is anaesthetised there before dehorning.
- Actinomycosis (lumpy jaw): osteomyelitis caused by Actinomyces bovis; it affects the mandible more often, but also the maxilla.