The medical term that pertains to the neck is "cervical," and the medical term that refers to the arms is "appendicular." According to Dictionary.com, the term "cervix" refers to the neck or any neck-like part of an organ.
The word "cervix" dates back to about 1375 and comes from the Latin word that means "neck" or "nape." It is commonly used to describe the constricted lower portion of the uterus that connects to the vagina.
The term "appendicular" is commonly used in anatomy to refer to an appendage or limb. The word "brachium" is used to describe the part of the arm that extends from the shoulder to the elbow.