Piriform fossae Health Dictionary

A term applied to various depressions or holes, both on the surface of the body and in internal parts, such as the iliac fossa in each lower corner of the abdomen, and the fossae within the skull which lodge the di?erent parts of the brain.... fossa

A membrane wall separating two or more cavities, such as the one between the nasal fossae and those separating the air sacs (alveoli) of the lungs.... septum

n. the bone of the upper arm (see illustration). The head of the humerus articulates with the *scapula at the shoulder joint. At the lower end of the shaft the trochlea articulates with the *ulna and part of the radius. The radius also articulates with a rounded protuberance (the capitulum) close to the trochlea. Depressions (fossae) at the front and back of the humerus accommodate the ulna and radius, respectively, when the arm is flexed or straightened.... humerus

n. the largest gland of the body, weighing 1200–1600 g. Situated in the top right portion of the abdominal cavity, the liver is divided by fissures (fossae) into four lobes: the right (the largest lobe), left, quadrate, and caudate lobes. It is connected to the diaphragm and abdominal walls by five ligaments: the membranous falciform (which separates the right and left lobes), coronary, and right and left triangular ligaments and the fibrous round ligament, which is derived from the embryonic umbilical vein. Venous blood containing digested food is brought to the liver in the hepatic portal vein (see portal system). Branches of this vein pass in between the lobules and terminate in the sinusoids (see illustration).

Oxygenated blood is supplied in the hepatic artery. The blood leaves the liver via a central vein in each lobule, which drains into the *hepatic vein. The liver is supplied by parasympathetic nerve fibres from the vagus nerve, and by sympathetic fibres from the solar plexus. The liver has a number of important functions. It synthesizes *bile, which drains into the *gall bladder before being released into the duodenum. The liver is an important site of metabolism of carbohydrates, proteins, and fats. It regulates the amount of blood sugar, converting excess glucose to *glycogen; it removes excess amino acids by breaking them down into ammonia and finally *urea; and it stores and metabolizes fats. The liver also synthesizes *fibrinogen and *prothrombin (essential blood-clotting substances) and *heparin, an anticoagulant. It forms red blood cells in the fetus and is the site of production of plasma proteins. It has an important role in the detoxification of poisonous substances and it breaks down worn out red cells and other unwanted substances, such as excess oestrogen in the male (see also Kupffer cells). The liver is also the site of *vitamin A synthesis; this vitamin is stored in the liver, together with vitamins B12, D, and K.

The liver is the site of many important diseases, including *hepatitis, *cirrhosis, amoebic *dysentery, *hydatid disease, and *hepatomas.... liver

n. the organ of olfaction, which also acts as an air passage that warms, moistens, and filters the air on its way to the lungs. The external nose is a triangular projection in the front of the face that is composed of cartilage and covered with skin. It leads to the nasal cavity (internal nose), which is lined with mucous membrane containing olfactory cells and is divided into two chambers (fossae) by the nasal septum. The lateral wall of each chamber is formed by the three scroll-shaped *nasal conchae, below each of which is a groovelike passage (meatus). The *paranasal sinuses open into these meatuses.... nose