A surgical excision of a portion of the skull is known as:

A) craniectomy.
B) craniotomy.
C) diskectomy.
D) pallidotomy.

Craniectomy refers to the surgical removal of a portion of the skull bone to access and remove or repair underlying brain tissue. Craniotomy, on the other hand, refers to the surgical opening of the skull without removal of a bone flap, typically to access the brain for diagnostic or therapeutic purposes. Diskectomy is the surgical removal of an intervertebral disk, and pallidotomy is a type of brain surgery where a portion of the globus pallidus, a brain structure involved in motor control, is destroyed to treat movement disorders such as Parkinson's disease.