| hiatus of canal of lesser petrosal nerve | <anatomy, nerve> The small opening in the petrous bone lateral to the hiatus of facial canal that gives passage to the lesser petrosal nerve. Synonym: hiatus canalis nervi petrosi minoris, Arnold's canal, canalis nervi petrosi superficialis minoris. (05 Mar 2000) |
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| hiatus of facial canal | 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) |
| 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) |
| 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) |
| neural | 1. Pertaining to a nerve or to the nerves. 2. Situated in the region of the spinal axis, as the neutral arch. Origin: L. Neuralis, Gr. Neuron = nerve (18 Nov 1997) |
| neural arch | The posterior projection from the body of a vertebra that encloses the vertebral foramen; it consists of paired pedicles and laminae; the spinous, transverse, and articular processes arise from the arch. In aggregate, the venous arches-and the ligamenta flava that unite them-form the posterior wall of the vertebral (spinal) canal. Synonym: arcus vertebrae, neural arch. (05 Mar 2000) |
| neural axis | The central nervous system; the brain and spinal cord. Synonym: encephalomyelonic axis, neural axis. (05 Mar 2000) |
| neural canal | The canal within the embryonic neural tube; the primordium of the central canal. (05 Mar 2000) |
| neural cell adhesion molecule | See: NCAM. (18 Nov 1997) |
| neural crest | A group of embryonic cells that separate from the neural plate during neurulation and migrate to give several different lineages of adult cells: the spinal and autonomic ganglia, the glial cells of the peripheral nervous system and nonneuronal cells, such as chromaffin cells, melanocytes and some haemopoietic cells. (18 Nov 1997) |