Topography
The brain fills the cranial cavity. The olfactory bulbs, large in the dog, sit rostrally in the ethmoidal fossa, between the orbits. The cerebral hemispheres fill most of the vault; the cerebellum lies caudal to them in the caudal cranial fossa, separated from the cerebrum by the tentorium cerebelli, which is partly ossified in the dog. The brainstem rests on the floor of the skull and leaves through the foramen magnum towards the atlas.
Parts
- Cerebrum: two hemispheres with gyri and sulci, joined by the corpus callosum. Includes the olfactory bulbs and tracts.
- Cerebellum: median vermis and lateral hemispheres. Coordinates posture and movement.
- Brainstem (truncus encephali): midbrain, pons and medulla oblongata. Most cranial nerves arise from it.
Clinical relevance
- Idiopathic epilepsy: the most common cause of recurrent seizures in young and adult dogs.
- Hydrocephalus: common in toy and brachycephalic breeds, with a domed skull and persistent fontanelle.
- Chiari-like malformation: in the Cavalier King Charles Spaniel the cerebellum is pushed into the foramen magnum, often with syringomyelia.
- Meningioma: the most common intracranial tumour of older dogs.
3D model
Surface from an MRI population template of 30 mesaticephalic and dolichocephalic dogs (Cornell cortical atlas), scaled to the cranial cavity of the atlas skull. The brainstem ends at the medulla oblongata, where the template ends.