Dictionary

Rochalimaea quintana See Bartonella quintana.

rocker bottom feet A type of congenital anomaly of the feet in which the bottom of the foot is rounded, resembling the bottom of a rocking chair, and the calcaneus (heel bone) is unusually prominent. This anomaly usually occurs with other congenital defects and suggests the presence of a chromosomal abnormality.

Rocky Mountain spotted fever An acute febrile (feverish) disease that was initially recognized in the Rocky Mountain states. Abbreviated RMSF. RMSF is caused by Rickettsia rickettsii, transmitted by hard-shelled (ixodid) ticks, and occurs only in the Western hemisphere. Anyone frequenting tickinfested areas is at risk for RMSF. Onset of symptoms is abrupt, with headache, high…

rod A specialized light-sensitive cell (photoreceptor) in the retina that provides side vision and the ability to see objects in dim light (night vision). See also cone cell.

roentgen An international unit of X-ray or gamma-ray radiation.

roentgenology See radiology.

Rohypnol The trade name for flunitrazepam, which has been abused as a “date rape” drug. Rohypnol produces sedative-hypnotic effects including muscle relaxation and amnesia. It can produce physical and psychological dependence and can be lethal when mixed with alcohol and/or other depressants.

rooting reflex A reflex that is seen in normal newborn babies, who automatically turn the face toward the stimulus and make sucking (rooting) motions with the mouth when the cheek or lip is touched. The rooting reflex helps to ensure successful breastfeeding.

Rorschach test A common psychological test that involves using inkblots that show enigmatic and highly ambiguous shapes. Ten standardized blots are shown, one at a time, to a person, and the person’s responses are recorded, to determine what the person perceives about the inkblots.

rosacea A chronic skin disease that causes persistent redness over the areas of the face and nose that normally blush: mainly the forehead, the chin, and the lower half of the nose. The tiny blood vessels in these areas enlarge (dilate) and become more visible through the skin, appearing like tiny red lines (telangiectasias). Pimples…

roseola See measles.

rotator cuff A group of four tendons that stabilize the shoulder joint. Each of these tendons attaches to a muscle that moves the shoulder in a specific direction. The four muscles whose tendons form the rotator cuff are the subscapularis muscle, which moves the arm by turning it inward (internal rotation); the supraspinatus muscle, which…