| oblique sinus of pericardium | The recess in the pericardial cavity posterior to the base of the heart bounded laterally by the pericardial reflections on the pulmonary veins and inferior vena cava, and posteriorly by the pericardium overlying the anterior aspect of the oesophagus. Synonym: sinus obliquus pericardii, oblique sinus of pericardium. (05 Mar 2000) |
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| oblique vein of left atrium | A small vein on the posterior wall of the left atrium which merges with the great cardiac vein to form the coronary sinus; it is developed from the left common cardinal vein, and occasionally persists as a left superior vena cava. Synonym: vena obliqua atrii sinistri, Marshall's oblique vein. (05 Mar 2000) |
| tendon sheath of superior oblique muscle | <anatomy> The synovial sheath enclosing the tendon of the superior oblique muscle as it passes through the trochlea. Synonym: vagina tendinis musculi obliqui superioris, synovial trochlear bursa, trochlear synovial bursa, vagina synovialis trochleae. (05 Mar 2000) |
| external oblique | <anatomy, muscle> Origin, fifth to twelfth ribs; insertion, anterior half of lateral lip of iliac crest, inguinal ligament, and anterior layer of the rectus sheath; action, diminishes capacity of abdomen, draws thorax downward; nerve supply, thoracoabdominal nerves. Synonym: musculus obliquus externus abdominis, abdominal external oblique muscle. (05 Mar 2000) |
| external oblique reflex | Contraction of the external oblique and rectus abdominis muscles upon tapping the anterior and outer part of the lower thoracic wall. (05 Mar 2000) |
| external oblique ridge | A horizontal bony crest on the external surface of the body of the mandible, inferior to the alveolar bone, marking the site of attachment of the buccinator muscle. (05 Mar 2000) |
| extinction oblique | <microscopy> Vibration directions oblique to the long direction of the crystal or fibre. (05 Aug 1998) |
| lateral oblique radiograph | A radiographic view of the mandible, revealing one side of the mandible from symphysis to condyle by displacing the other side upwards. (05 Mar 2000) |
| aditus glottidis inferior | The part of the cavity of the larynx immediately below the glottis. Synonym: cavitas infraglotticum, aditus glottidis inferior, cavum infraglotticum, inferior laryngeal cavity, infraglottic space. (05 Mar 2000) |
| angulus inferior scapulae | The acute angle formed by junction of the medial and lateral borders of the scapula. Synonym: angulus inferior scapulae. (05 Mar 2000) |
| anterior inferior cerebellar artery | <anatomy, artery> Origin, basilar; distribution, lower surface of lateral lobes of cerebellum, choroid plexus in cerebellopontine angle; anastomoses, posterior inferior cerebellar; usual source of labyrinthine artery. Synonym: arteria cerebelli inferior anterior. (05 Mar 2000) |
| anterior inferior iliac spine | Spine on the anterior border of the ilium between the anterior superior iliac spine and the acetabulum; site of origin for the direct head of the rectus femoris muscle. Synonym: spina iliaca anterior inferior. (05 Mar 2000) |
| anterior inferior segment | Anterior inferior segment of kidney. Synonym: segmentum anterius inferius. (05 Mar 2000) |
| anterior inferior segmental artery of kidney | Origin, anterior branch of renal. See: segmental arteries of kidney. Synonym: arteria segmenti anterioris inferioris renis, artery of anterior {inferior segment of kidney}. (05 Mar 2000) |
| apertura pelvis inferior | The lower opening of the true pelvis, bounded anteriorly by the pubic arch, laterally by the rami of the ischium and the sacrotuberous ligament on either side, and posteriorly by these ligaments and the tip of the coccyx. Synonym: apertura pelvis inferior, apertura pelvis minoris, fourth parallel pelvic plane, pelvic outlet, pelvic plane of outlet, plane of outlet. (05 Mar 2000) |