The term “infundibulum” is used to describe any anatomical structure which has a funnel-like shape, whether the structure forms an opening or is solid in nature. A number of structures can be referred to as infundibula, ranging from structures inside the ears to parts of the kidneys, and including everything from solid bones to funnel-like tubes which are used to move air or fluids around inside the body. The specific body part being referenced is usually clear from the context in which the word is used, although there are alternate names for many of these anatomical structures which can be used for clarity.
In women, the area of the fallopian tube which opens to the ovary is known as the infundibulum. Working up through the body, people of all sexes have infundibula in their kidneys, also known as calyxes. These structures are part of the filtration and drainage system which keeps fluid moving through the kidneys so that it can be processed to remove waste products, retain necessary salts, and keep the balance of salts in the blood stable.
The heart also has an infundibulum, known as the conus arteriosus, which carries outflow away from the right ventricle. Likewise, the lungs have infundibula in the form of alveolar sacs. The ear also contains a structure known as the infundibulum, inside the cochlea of the ear, which plays a role in hearing and the processing of sound.
Yet another structure known as an infundibulum on occasion is the pituitary stalk, which descends from the pituitary gland in the brain. This structure connects the pituitary to the hypothalamus of the brain, and it is involved in the release of hormones produced in the pituitary gland. There's another structure near the brain sometimes known as the infundibulum; the ethmoid bone or ethmoid infundibulum which makes up part of the eye socket. This bone is situated between the brain and the nasal cavity and acts as a barrier between these two areas.
The term “infundibulum” can also be seen in use in a nonmedical setting. It is sometimes used in geometry, for example, to describe shapes with a funnel like appearance, and in other settings when people wish to describe something as funnel-like. The adjectival form of this word is “infundibular,” incidentally, for any wiseGEEK readers who suspect that they may have a pressing need to describe something with a funnel-like appearance in the near future.