fissure

A fissure is a narrow opening or crack in a solid material, often long and irregular. Fissures form through stress, weathering, cooling, or developmental processes and can occur in natural environments, living tissues, or manufactured materials. They may be purely structural features or pathways for fluids and other processes.

In geology, fissures are fractures along which there is little or no significant displacement. They occur in rocks due to tectonic forces or cooling and can act as conduits for water and hydrothermal fluids. Fissures may host mineral veins or contribute to fissure eruptions in volcanic settings, where lava or gases emerge from a linear crack rather than a central vent.

In medicine, fissures denote tears in tissue linings. The most common example is an anal fissure, a painful tear in the anoderm that can result from constipation or trauma. Other mucosal fissures may occur on the lips, inside the mouth, or within the nasal passages, often linked to irritation, inflammation, infection, or impaired blood flow. Treatment aims to relieve symptoms and promote healing, including dietary changes, topical medications, and, in persistent cases, surgical procedures.

In dentistry, fissures describe deep grooves in tooth enamel, particularly on chewing surfaces, which can trap bacteria and lead to caries. Preventive measures include fissure sealants that occlude grooves to reduce decay risk.

In neuroanatomy, fissures are deep grooves in the brain, such as the longitudinal fissure that separates the two cerebral hemispheres, helping to delineate lobes and structures.