| hiatus sacralis | A normally-occurring gap at the lower end of the sacrum, exposing the vertebral canal, due to failure of the laminae of the last sacral segment to coalesce. It is closed by the sacrococcygeal ligament, and provides cannular access to the sacral epidural space for administration of anaesthetics (caudal nerve blocks). Synonym: hiatus sacralis. (05 Mar 2000) |
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| hiatus saphenus | The opening in the fascia lata inferior to the medial part of the inguinal ligament through which the saphenous vein passes to enter the femoral vein. Synonym: hiatus saphenus, fossa ovalis, saphenous hiatus. (05 Mar 2000) |
| hiatus semilunaris | A deep, narrow groove in the lateral wall of the middle meatus of the nasal cavity, into which the maxillary sinus, the frontonasal duct, and the middle ethmoid cells open. Synonym: hiatus semilunaris, hiatus ethmoidalis. (05 Mar 2000) |
| hiatus subarcuatus | An irregular depression on the posterior surface of the petrous portion of the temporal bone just below its crest and above and lateral to the internal acoustic meatus. In the foetus, the flocculus of the cerebellum rests here; in the adult, a small vein enters the bone here. Synonym: fossa subarcuata, floccular fossa, hiatus subarcuatus. (05 Mar 2000) |
| hiatus tendineus | The aperture in the aponeurotic insertion of the adductor magnus that transmits the femoral artery and vein from the adductor canal to the popliteal space. Synonym: hiatus tendineus, hiatus adductorius, femoral opening, tendinous opening. (05 Mar 2000) |
| hiatus totalis sacralis | Developmental clefting in all sacral vertebrae; may also involve adjacent lumbar vertebrae. (05 Mar 2000) |
| semilunar hiatus | A deep, narrow groove in the lateral wall of the middle meatus of the nasal cavity, into which the maxillary sinus, the frontonasal duct, and the middle ethmoid cells open. Synonym: hiatus semilunaris, hiatus ethmoidalis. (05 Mar 2000) |
| oesophageal hiatus | The opening in the right crus of the diaphragm, between the central tendon and the hiatus aorticus, through which pass the oesophagus and the two vagus nerves. Synonym: hiatus oesophageus, oesophageal opening. (05 Mar 2000) |
| fallopian hiatus | The opening on the anterior aspect of the petrous part of the temporal bone which leads to the facial canal and gives passage to the greater petrosal nerve. Synonym: hiatus canalis nervi petrosi majoris, fallopian hiatus, Ferrein's foramen, hiatus canalis facialis, hiatus of canal for greater petrosal nerve. (05 Mar 2000) |