What is the term for a fold or septum located on the posterior wall between the body and neck of the gallbladder?

The term for a fold or septum located on the posterior wall between the body and neck of the gallbladder is known as the junctional fold. This anatomical feature is an important consideration during ultrasound examinations, as it can affect the appearance of the gallbladder and possibly mimic pathology. The junctional fold can create echogenic shadows or artifacts that may complicate the interpretation of ultrasound images.

In understanding this, it's crucial to recognize that this anatomical configuration is distinct from other related terms. For instance, a Phrygian cap refers to a variant where the gallbladder body is folded upon itself, more common in the overall shape of the organ rather than specifically in the posterior wall between the body and neck. Hartman's pouch, on the other hand, describes an anatomical variation that occurs at the neck of the gallbladder and is related to gallstone formation rather than the posterior wall. The spiral valve, found within the cystic duct, functions differently and relates to the flow of bile rather than to a fold or septum in the gallbladder itself. Understanding these distinctions helps clarify the anatomical terminology used in radiology and is essential for correctly identifying and interpreting gallbladder anatomy on imaging studies.