| inferior oblique muscle of head | <anatomy, muscle> Origin, spinous process of axis; insertion, transverse process of the atlas; action, rotates head; origin, spinous process of axis; insertion, transverse process of the atlas; nerve supply, suboccipital. See: suboccipital muscles. Synonym: musculus obliquus capitis inferior, inferior oblique muscle of head. (05 Mar 2000) |
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| inferior occipital gyrus | A gyrus situated below the lateral occipital sulcus on the lower part of the lateral surface of the occipital lobe. (05 Mar 2000) |
| inferior occipital triangle | A triangle with its apex at the external occipital protuberance; its base is formed by a line joining the two mastoid processes. (05 Mar 2000) |
| inferior oesophageal sphincter | A sphincter supposedly present at the oesophagogastric junction; this is in fact an extrinsic sphincter formed by the surrounding musculature of the oesophageal hiagus of the right crus of the diaphragm; causes a normally-occuring constriction at the oesophagogastric junction observable with a barium swallow. Synonym: sphincter constrictor cardiae. (05 Mar 2000) |
| inferior olivary nucleus | A large aggregate of small densely packed nerve cells arranged in folded laminae shaped like a purse with the opening (hilum) directed medially. It corresponds in position to the oliva, projects to all parts of the contralateral half of the cerebellar cortex by way of the olivocerebellar tract, and is the only source of cerebellar climbing fibres. Its afferent connections include fibres from the spinal cord, the dentate nucleus and motor cortex, but its major input appears to be the central tegmental tract originating from multiple nuclei at midbrain levels. Synonym: nucleus olivaris. (05 Mar 2000) |
| inferior olive | <zoology> A genus of polished marine gastropod shells, chiefly tropical, and often beautifully coloured. Origin: L. An olive. Source: Websters Dictionary (01 Mar 1998) |
| inferior omental recess | A recess of the omental bursa extending between anterior and posterior layers of the great omentum. Synonym: recessus inferior omentalis. (05 Mar 2000) |
| inferior ophthalmic vein | <anatomy, vein> Arises from the inferior palpebral and lacrimal veins and divides into two terminal branches, one of which runs to the pterygoid plexus while the other joins the superior ophthalmic vein or empties into the cavernous sinus. Synonym: vena ophthalmica inferior. (05 Mar 2000) |
| inferior orbital fissure | A cleft between the greater wing of the sphenoid and the orbital plate of the maxilla, through which pass the maxillary division and the orbital branch of the trigeminal nerve, fibres from the pterygopalatine (Meckel's) ganglion, and the infraorbital vessels. Synonym: fissura orbitalis inferior, sphenomaxillary fissure. (05 Mar 2000) |
| inferior palpebral veins | Veins of inferior eyelid; veins originatin gin the inferior eyelid and emptying into the angular vein. Synonym: venae palpebrales inferiores, veins of inferior eyelid. (05 Mar 2000) |
| inferior pancreatic artery | <anatomy, artery> Origin, dorsal pancreatic; distribution, body and tail of pancreas; anastomoses, great pancreatic artery. Synonym: arteria pancreatica inferior, transverse pancreatic artery. (05 Mar 2000) |
| inferior pancreaticoduodenal artery | <anatomy, artery> Origin, superior mesenteric; one of two arteries, anterior and posterior; distribution, head of pancreas, duodenum; anastomoses, superior pancreaticoduodenal. Synonym: arteria pancreaticoduodenalis inferior. (05 Mar 2000) |
| inferior parietal gyrus | The area of the parietal lobe of the cerebrum lying below the interparietal sulcus; it contains the angular and the supramarginal gyri. Synonym: lobulus parietalis inferior, inferior parietal gyrus. (05 Mar 2000) |
| inferior parietal lobule | The area of the parietal lobe of the cerebrum lying below the interparietal sulcus; it contains the angular and the supramarginal gyri. Synonym: lobulus parietalis inferior, inferior parietal gyrus. (05 Mar 2000) |
| inferior part | The lowermost portion of a structure relative to the other parts; portion closest to the soles of the feet. See: inferior part of duodenum, inferior part of lingular branch of left pulmonary vein, inferior part of vestibular ganglion. Synonym: pars inferior. (05 Mar 2000) |