What do we refer to as a long, narrow depression in a bone?

A long, narrow depression in a bone is referred to as a fissure. This term specifically describes a narrow opening, groove, or slits between bones or within a bone, which can serve several functions such as facilitating the passage of nerves, blood vessels, or other structures. Fissures are often found in the skull and provide pathways for cranial nerves or veins. This distinguishes them from other terms used to describe bone depressions, which may have different shapes, sizes, or implications in anatomical context. Understanding these features is crucial for identifying and studying various anatomical structures and their functions.