| spinal part of arachnoid | That portion of the arachnoid which lies within the vertebral canal and surrounds the spinal cord and the vertebral portion of the subarachnoid space. It extends from the foramen magnum above to the S-2 vertebral level. Since the spinal cord ends at the L-2 vertebral level, a wide separation occurs between the arachnoid and pia mater, the lumbar cistern, filled with cerebrospinal fluid in which the cauda equina is suspended. Synonym: arachnoidea mater spinalis, spinal part of arachnoid. (05 Mar 2000) |
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| spinal point | The centre of the root of the anterior nasal spine. Synonym: apophysary point, apophysial point, spinal point. (05 Mar 2000) |
| spinal puncture | Tapping of the subarachnoid space in the lumbar region, usually between the third and fourth lumbar vertebrae. (12 Dec 1998) |
| spinal quotient | The cerebrospinal index when 10 ml of cerebrospinal fluid have been removed. Synonym: Ayala's quotient, spinal quotient. (05 Mar 2000) |
| spinal reflex | A reflex arc involving the spinal cord. See: reflex arc. (05 Mar 2000) |
| spinal root of accessory nerve | <anatomy, nerve> Originates from the upper five or six cervical spinal segments, emerges from the lateral surface of the spinal cord and ascends through the foramen magnum to join the cranial root. Synonym: radices spinales nervi accessorii, ramus externus nervi accessorii, pars spinalis nervi accessorii, spinal part of accessory nerve. (05 Mar 2000) |
| spinal shock | Transient depression or abolition of reflex activity below the level of an acute spinal cord injury or transection. (05 Mar 2000) |
| spinal sign | <clinical sign> In pleurisy, the spinal muscles are in a state of tonic contraction on the affected side. (05 Mar 2000) |
| spinal stenosis | An abnormal narrowing of the spinal canal that may be either congenital or acquired. Treatment is generally surgical to widen the spinal canal. Laminectomy may be the indicated surgical procedure to reduce pressure on the spinal cord. (27 Sep 1997) |
| spinal stroke | Abrupt onset of focal spinal cord dysfunction caused by a disturbance in its blood supply. (05 Mar 2000) |
| spinal tap | A diagnostic procedure where a sterile needle is introduced into the lower spine (L2) to collect cerebrospinal fluid for diagnostic purposes. Chemical analysis, cellular analysis and CSF pressure can all be measured with this procedure. This test can aid in the diagnosis of meningitis, subarachnoid haemorrhage and multiple sclerosis. (27 Sep 1997) |
| spinal tract | Any one of a multitude of fibre bundles ascending or descending in the spinal cord. (05 Mar 2000) |
| spinal tract of trigeminal nerve | <anatomy, nerve> A compact fibre bundle, comma-shaped on transverse section, composed of primary sensory fibres of the portio major of the trigeminal nerve, descending from the level of the entrance of the trigeminus in the upper pons down through the dorsolateral region of the rhombencephalic tegmentum along the lateral side of the descending or spinal nucleus of the trigeminus, emerging on the dorsolateral surface of the lower medulla oblongata as the tuberculum cinereum, and continuing as far as the second cervical segment of the spinal cord. Its fibres are distributed to the descending or spinal nucleus of the trigeminus. Synonym: tractus spinalis nervi trigemini, descending tract of trigeminal nerve, tractus descendens nervi trigemini. (05 Mar 2000) |
| spinal tractotomy | Division of the anterolateral quadrant of the spinal cord to section the spinothalamic tract. Synonym: anterolateral tractotomy, spinal tractotomy, spinothalamic cordotomy. (05 Mar 2000) |
| spinal trigeminal nucleus | The long sensory nucleus extending from the caudal border of the pontine sensory nucleus of the trigeminus down through the lateral region of the rhombencephalon into the upper three segments of the spinal cord's dorsal horn; it receives the fibres of the sensory root of the trigeminal nerve which descend along its lateral border as the spinal tract of trigeminal nerve. Synonym: nucleus tractus spinalis nervi trigemini, descending nucleus of the trigeminus, spinal nucleus of the trigeminus. (05 Mar 2000) |