lobe

A lobe is a distinct projection or division of an organ or body part, typically separated from adjacent tissue by natural boundaries such as fissures, grooves, or folds. In anatomy, lobes are regions that may have somewhat different structure or function, but boundaries between them can be gradual rather than sharp.

In the brain, the cerebral cortex is commonly described as comprising four main lobes: the frontal, parietal, temporal, and occipital lobes. Each lobe is associated with broad functions, such as movement and planning in the frontal lobe, sensory processing in the parietal lobe, auditory and memory processing in the temporal lobe, and vision in the occipital lobe. Some references also include the insular region as a separate lobe. The lungs have lobes as well: the right lung has three lobes (upper, middle, lower) and the left lung has two (upper and lower); each lobe is supplied by its own bronchus and blood vessels.

The liver is divided into right and left lobes, with smaller structures sometimes described as caudate and quadrate lobes. These divisions help describe anatomy and guide surgical procedures even though many functions are integrated across the organ. The term lobe also appears in general language to describe the soft, rounded lower part of the external ear (the earlobe) and in botany to describe lobed leaves, where leaf margins create lobes.

Clinically, lobes provide a framework for diagnosing regions of disease and planning interventions, such as lobectomy in lung surgery or liver resection. The concept of a lobe reflects the way organisms organize tissue into modular, functionally coherent units.