Congenital herniation or coning of the cerebellar tonsils through the foramen magnum can also occur if the posterior fossa is too small, a condition known as Chiari I malformation (Fig. 8.52). This often causes no problems in childhood and may only start causing symptoms in adulthood.
In the clinic
In the clinic
Overview of cranial nerves
Afferent—Trigeminal nerve (CN V)
Efferent—Facial nerve (CN VII)