Dictionary

fracture, compound A fracture in which a bone is sticking through the skin. Also known as an open fracture.

fracture, comminuted A fracture in which a bone is broken, splintered, or crushed into a number of pieces.

fracture, clay-shoveler’s An uncommon breakage of the spine, of the vertebrae from the lower neck or upper back, that results from stress. Clayshoveler’s fracture usually occurs in laborers who rapidly lift heavy weights with their arms extended, such as in shoveling. Symptoms of clay-shoveler’s fracture include burning, knife-like pain at the level of the fractured…

fracture, buckle See fracture, torus.

fracture A break in bone or cartilage. Although usually a result of trauma, a fracture can be the result of an acquired disease of bone, such as osteoporosis, or of abnormal formation of bone in a congenital disease of bone, such as osteogenesis imperfecta (“brittle bone disease”). Fractures are classified according to their character and…

fraction, ejection See ejection fraction.

fourth ventricle One cavity in a system of four communicating cavities within the brain, which are continuous with the central canal of the spinal cord. The fourth ventricle is the most inferior (lowest) of these. It extends from the aqueduct of the midbrain to the central canal of the upper end of the spinal cord,…

fourth stage of labor The hour or two after delivery when the tone of the uterus is reestablished as the uterus contracts again, expelling any remaining contents. These contractions are hastened by breastfeeding, which stimulates production of the hormone oxytocin.

founder effect The positive effect on gene frequency when a population (colony) has only a small number of original settlers, one or more of whom had that gene. For example, the gene for Huntington’s disease was introduced into the Lake Maracaibo region in Venezuela early in the nineteenth century. This is now the largest known…

fornix vaginae See fornix uteri.

fornix uteri The anterior (front) and posterior (back) recesses into which the upper vagina is divided. These vaultlike recesses are formed by protrusion of the cervix into the vagina. The fornix uteri is also known as the fornix vaginae (or the vaginal fornices) and the uterine fornices.

fornix conjunctivae The loose arching folds that connect the conjunctival membrane lining the inside of the eyelid with the conjunctival membrane covering the eyeball.