What is the term for congenital anomalies of the hindbrain characterized by caudal displacement of pons, medulla, and cerebellar vermis?

The term for congenital anomalies of the hindbrain that involves the caudal displacement of the pons, medulla, and cerebellar vermis is indeed Arnold-Chiari malformation. This condition is characterized by the descent of the cerebellar tonsils through the foramen magnum, leading to potential obstruction of cerebrospinal fluid (CSF) flow and resultant complications such as headaches, balance issues, and neurological symptoms.

Arnold-Chiari malformation primarily affects the development and positioning of the brain structures at the back of the skull and is distinct from other conditions like Down syndrome, which is a genetic disorder caused by an extra chromosome 21. Spina bifida involves a defect in the closure of the neural tube leading to spinal cord abnormalities, and DiGeorge syndrome is characterized by a deletion on chromosome 22, which leads to developmental issues affecting multiple systems, particularly the immune system and heart. Thus, the specific features of Arnold-Chiari malformation set it apart, making it the correct answer in this context.