| LL | large lymphocyte; lateral leminiscus; left lateral; left leg; left lower; left lung; lepromatous [in... |
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| LLF | Laki-Lorand factor; left lateral femoral; left lateral flexion |
| LR | labeled release; laboratory references; laboratory report; labor room; lactated Ringer [solution]; l... |
| LRS | lactated Ringer solution; lateral recess stenosis; lateral recess syndrome; low rate of stimulation;... |
| LVN | lateral ventricular nerve; lateral vestibular nucleus; Licensed Visiting Nurse; Licensed Vocational ... |
| medullary pyramid | One of a number of pyramidal masses seen on longitudinal section of the kidney; collectively, they constitute the renal medulla, and contain part of the secreting tubules and the collecting tubules. Synonym: pyramis renalis, malpighian pyramid, medullary pyramid. (05 Mar 2000) |
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| medullary ray | The centre of the renal lobule, which has the shape of a small, steep pyramid, consisting of straight tubular parts; these may be either ascending or descending limbs of the nephronic loop or collecting tubules. Synonym: pars radiata lobuli corticalis renis, Ferrein's pyramid, processus ferreini. (05 Mar 2000) |
| medullary sarcoma | <tumour> A soft, extremely vascular sarcoma. (05 Mar 2000) |
| medullary sheath | <anatomy, neurology> An insulating layer surrounding vertebrate peripheral neurons, that dramatically increases the speed of conduction. It is formed by specialised Schwann cells, that can wrap around neurons up to 50 times. The exposed areas are called nodes of Ranvier: they contain very high densities of sodium channels and action potentials jump from one node to the next, without involving the intermediate axon, a process known as saltatory conduction. (18 Nov 1997) |
| medullary space | The central cavity and the cellular intervals between the trabeculae of bone, filled with marrow. (05 Mar 2000) |
| medullary spinal arteries | A large caliber spinal or radicular artery which courses centrally along a dorsal or ventral root, perhaps supplying it and the surrounding meninges in the fashion of any spinal/radicular artery, but which continues on to reach and anastomose with the anterior or posterior (longitudinal) spinal artery. Only 4-9 of the spinal arteries are medullary spinal arteries, found mainly in the lower cervical, lower thoracic and upper lumbar levels, the largest of which is the great radicular artery. (05 Mar 2000) |
| medullary sponge kidney | <radiology> Renal tubular ectasia, dilatation and cyst formation of collecting tubules in renal pyramids, Calcium most likely to be medullary nephrocalcinosis, not hereditary; males (2:1), usually bilateral associated with, renal tubular acidosis (RTA), Caroli disease, parathyroid adenoma, hypertrophic pyloric stenosis, Ehlers-Danlos syndrome, ipsilateral hemihypertrophy (12 Dec 1998) |
| medullary striae of fourth ventricle | Slender fascicles of fibres extending transversally below the ependymal floor of the ventricle from the median sulcus to enter the inferior cerebellar peduncle. They arise from the arcuate nuclei on the ventral surface of the medullary pyramid. Synonym: striae medullares ventriculi quarti, acoustic striae, auditory striae, Bergmann's cords, medullary teniae, teniae acusticae. (05 Mar 2000) |
| medullary stria of thalamus | A narrow, compact fibre bundle that extends along the line of attachment of the roof of the third ventricle to the thalamus on each side and terminates posteriorly in the habenular nucleus. It is composed of fibres originating in the septal area, the anterior perforated substance, the lateral preoptic nucleus, and the medial segment of the globus pallidus. Synonym: stria medullaris thalami, stria fornicis, stria ventriculi tertii. (05 Mar 2000) |
| medullary substance | The lipid material present in the myelin sheath of nerve fibres. Synonym: Schwann's white substance. (05 Mar 2000) |
| medullary teniae | Slender fascicles of fibres extending transversally below the ependymal floor of the ventricle from the median sulcus to enter the inferior cerebellar peduncle. They arise from the arcuate nuclei on the ventral surface of the medullary pyramid. Synonym: striae medullares ventriculi quarti, acoustic striae, auditory striae, Bergmann's cords, medullary teniae, teniae acusticae. (05 Mar 2000) |
| medullary tube | <embryology> The progenitor of the central nervous system. See: neural plate, neurulation. (18 Nov 1997) |
| posterior 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) |
| neoplasms, ductal, lobular, and medullary | Neoplasms, usually carcinoma, located within the centre of an organ or within small lobes, and in the case of the breast, intraductally. The emphasis of the name is on the location of the neoplastic tissue rather than on its histological type. most cancers of this type are located in the breast. (12 Dec 1998) |
| superior medullary velum | The thin layer of white matter stretching between the two superior cerebellar peduncles, forming the roof of the superior recess of the fourth ventricle. Synonym: velum medullare superius, anterior medullary velum, Vieussens' valve. (05 Mar 2000) |