| prelaminar part of optic nerve | <anatomy, nerve> The portion of the optic nerve anterior to the lamina cribrosa of the sclera. Synonym: pars prelaminaris nervi optici. (05 Mar 2000) |
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| prevertebral part of vertebral artery | See: vertebral artery. (05 Mar 2000) |
| sacral part of spinal cord | The part of the cord from which consists of the five sacral segments of the spinal cord (S1-S5) and from which five pairs of sacral nerves originate. Synonym: pars sacralis medullae spinalis, segmenta medullae spinalis sacralia. (05 Mar 2000) |
| sarcoma, alveolar soft part | A variety of sarcoma having a reticulated fibrous stroma enclosing groups of sarcoma cells, which resemble epithelial cells and are enclosed in alveoli walled with connective tissue. It is a rare tumour, usually occurring between 15 and 35 years of age. It appears in the muscles of the extremities in adults and most commonly in the head and neck region of children. Though slow-growing, it commonly metastasizes to the lungs, brain, bones, and lymph nodes. (12 Dec 1998) |
| hidden part | <anatomy> An obsolete term, pars tecta duodeni, the part of duodenum covered by the root of the transverse mesocolon, the coalescence of the ascending mesocolon, and the root of the mesentery, pars tecta pancreatis, hidden portion of the pancreas; part of the pancreas covered by the root of the transverse mesocolon, the coalescence of the ascending mesocolon, and the root of the mesentery, pars tecta renalis, hidden portion of the kidney; part of the kidney covered by the root of the transverse mesocolon, pars tecta ureteralis, hidden portion of the ureter; part of the right ureter covered (crossed) by the root of the mesentery, and of the left ureter covered (crossed) by the root of the sigmoid mesocolon. Synonym: hidden part. (05 Mar 2000) |
| pterygopharyngeal part of superior constrictor muscle of pharynx | pterygopharyngeal part of superior constrictor muscle of pharynx |
| horizontal part of duodenum | pars horizontalis duodeni, inferior part of duodenum, pars inferior duodeni |
| horizontal part of facial canal | First portion of facial canal, between beginning of canal (at the introitus of the facial canal at the end of the internal auditory meatus) and the point at which it turns to descend, beginning the descending part. There are two components (crura) of the horizontal part: the medially-located, anteriorly-directed medial crus and the laterally-placed, posteriorly-directed lateral crus, the two being continuous at a sharp bend, the genu of the facial canal. This lateral part is where the genicular ganglion is located and which communicates with the middle cranial fossa via the hiatus of the facial canal, through which the greater superficial petrosal nerve passes. (05 Mar 2000) |
| sphenoidal part of middle cerebral artery | sphenoidal part of middle cerebral artery |
| spinal part 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 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) |
| spongy part of the male urethra | The portion of the male urethra, about 15 cm in length, which traverses the corpus spongiosum. Synonym: pars spongiosa urethrae masculinae, pars cavernosa, penile urethra, spongy part of the male urethra. (05 Mar 2000) |
| squamous part of frontal bone | The broad curved portion of the frontal bone forming the forehead. Synonym: squama frontalis. (05 Mar 2000) |
| squamous part of occipital bone | The tabular or squamous portion of occipital bone. Synonym: squama occipitalis, occipital squama, frontal squama. (05 Mar 2000) |
| squamous part of temporal bone | The broad, flat, thin (scale-like) anterior and superior portion of the temporal bone forming part of the lateral wall of the cranial vault. Synonym: pars squamosa ossis temporalis, squama temporalis, temporal squama. (05 Mar 2000) |