Category: O

The upright or nearly upright position of the upper trunk of a patient in a bed or chair. It facilitates breathing in those with congestive heart failure and some forms of pulmonary disease.  

In radiology, an alignment of the body between a lateral and an anteroposterior or posteroanterior position. The angle formed by the body surface and the image receptor may vary. The central ray enters the aspect of the body that is upright and facing away from the image receptor.  

The posterior extremity of the occipital lobe.  

Acute poisoning occurring when oxalic acid is accidentally ingested or when large quantities of foods rich in oxalic acid are eaten. Ingestion of 5 g of oxalic acid may be fatal. Chronic poisoning may result from inhalation of vapors.  

Intoxication by injected, inhaled, dermal, or orally consumed opiate or opioid analgesics.  

A pneumothorax in which the pleural cavity is exposed to the atmosphere through an open wound in the chest wall.    

The outer surface of the occipital bone lying above the superior nuchal line.  

A placode that first gives rise to the olfactory pit and later to the major portion of the nasal cavity.  

Phlebitis in which the lumen of a vein becomes permanently closed.  

In Parkinson’s patients, the alternating periods of good control (“on”) and poor control (“off’) of their symptoms. The on-off phenomenon is often experienced in patients undergoing L-dopa therapy.