<s>[INST] <<SYS>> This is a medical question of type : information <</SYS>> What is (are) Colpocephaly ? [/INST] Colpocephaly is a congenital brain abnormality in which the occipital horns - the posterior or rear portion of the lateral ventricles (cavities) of the brain - are larger than normal because white matter in the posterior cerebrum has failed to develop or thicken. </s>