| inferior mediastinum | The region below a plane transecing the T4/5 intervertebral disc posteriorly and the sternal angle anteriorly, demarcating the inferior limit of the superior mediastinum. It is subdivided into three regions: middle, anterior, and posterior. Synonym: mediastinum inferius. (05 Mar 2000) |
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| inferior medullary velum | A thin sheet of white matter, hidden by the cerebellar tonsil, attached along the peduncle of the flocculus and, at and near the midline, to the nodulus of the vermis; it is continuous caudally with the epithelial lamina and choroid plexus of the fourth ventricle. Synonym: velum medullare inferius, posterior medullary velum, Tarin's valve, valvula semilunaris tarini, velum semilunare, velum tarini. (05 Mar 2000) |
| inferior mesenteric artery | <anatomy, artery> Origin, abdominal aorta; branches, left colic, sigmoid, superior rectal; anastomoses, middle colic and middle rectal. Synonym: arteria mesenterica inferior. (05 Mar 2000) |
| inferior mesenteric ganglion | The lowest of the sympathetic prevertebral ganglia, located at the origin of the inferior mesenteric artery from the aorta and containing the sympathetic neurons innervating the descending and sigmoid colon. Synonym: ganglion mesentericum inferius. (05 Mar 2000) |
| inferior mesenteric lymph nodes | Nodes located along the inferior mesenteric artery and its branches that drain the upper part of the rectum, the sigmoid colon, and descending colon. Synonym: nodi lymphatici mesenterici inferiores. (05 Mar 2000) |
| inferior mesenteric plexus | An autonomic plexus, derived from the abdominal aortic plexus, surrounding the inferior mesenteric artery and sending branches to the descending colon, sigmoid, and rectum. Synonym: plexus mesentericus inferior. (05 Mar 2000) |
| inferior mesenteric vein | <anatomy, vein> A continuation of the superior rectal vein at the brim of the pelvis, ascending to the left of the aorta behind the peritoneum and emptying into the splenic vein or into the superior mesenteric vein or rarely in the angle between these veins. Synonym: vena mesenterica inferior. (05 Mar 2000) |
| inferior myocardial infarction | Infarction in which the inferior or diaphragmatic wall of the heart is involved, producing indicative changes in leads II, III, and aVF in the electrocardiogram. Synonym: diaphragmatic myocardial infarction. (05 Mar 2000) |
| inferior nasal arteriole of retina | The branch of the central artery of the retina that supplies the lower medial, or nasal, part of the retina. Synonym: arteriola nasalis retinae inferior. (05 Mar 2000) |
| inferior nasal colliculus | The ovoid, paired, inferior eminence of the laminae of mesencephalic tectum; it receives the lateral lemniscus and projects by way of the brachium of inferior colliculus to the medial geniculate body of the thalamus, and is thus an essential way-station in the central auditory pathway. Synonym: colliculus inferior, corpus quadrigeminum posterius, inferior nasal colliculus, posterior quadrigeminal body. (05 Mar 2000) |
| inferior nasal concha | A thin, spongy, bony plate with curved margins, on the lateral wall of the nasal cavity, separating the middle from the inferior meatus; it articulates with the ethmoid, lacrimal, maxilla, and palate bones, the above bony plate and its thick mucoperiosteum containing an extensive cavernous vascular bed for heat exchange. Synonym: concha nasalis inferior, inferior turbinated bone, turbinated body. (05 Mar 2000) |
| inferior nasal venule of retina | The small vein that passes from the inferior medial (nasal) part of the retina to join the central vein. Synonym: venula nasalis retinae inferior. (05 Mar 2000) |
| inferior nuchal line | A ridge that extends laterally from the external occipital crest toward the jugular process of the occipital bone. Synonym: linea nuchae inferior. (05 Mar 2000) |
| inferior oblique | <anatomy, muscle> Origin, orbital plate of maxilla lateral to the lacrimal groove; insertion, sclera between the superior and lateral recti; action, primary, extorsion; secondary, elevation and abduction; nerve supply, oculomotor (inferior branch). Synonym: musculus obliquus inferior. (05 Mar 2000) |
| 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) |