Flail chest
Flail chest: A condition that occurs when enough ribs are broken (usually from a crush injury) to compromise the rigidity of the chest wall. On inspiration, the chest wall moves inward instead of outward, and it does the opposite on expiration.
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Fourth disease: A disorder characterized by a rash due to a toxin produced by Staphylococcus aureus (Staph aureus bacteria). Measles and scarlet fever were differentiated from one another in the 17th century. Rubella was accepted as the third distinct pediatric exanthem (rash) in 1881. What were thought to be two distinct forms of rubella were […]
- Fourth stage of labor
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.
- Fourth ventricle
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, […]
- Fovea
Fovea: In the eye, a tiny pit located in the macula of the retina that provides the clearest vision of all. Only in the fovea are the layers of the retina spread aside to let light fall directly on the cones, the cells that give the sharpest image. Also called the central fovea or fovea […]
- 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 location […]