| membranous urethra | The portion of the male urethra, about 1 cm in length, extending from the prostate to the beginning of the urethra in the corpus spongiosum just beyond the bulb. Synonym: pars membranacea urethrae masculinae, membranous urethra. (05 Mar 2000) |
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| membranous wall of middle ear | The wall formed mainly by the tympanic membrane. Synonym: paries membranaceus cavi tympani, lateral wall of middle ear, membranous wall of middle ear. (05 Mar 2000) |
| membranous wall of trachea | The part of the tracheal wall posteriorly that is not reinforced by tracheal cartilages. Synonym: paries membranaceus tracheae. (05 Mar 2000) |
| common limb of membranous saemicircular ducts | The united, nonampullary ends of the superior and posterior saemicircular ducts. Synonym: crus membranaceum commune ductus saemicircularis, common limb of membranous saemicircular ducts. (05 Mar 2000) |
| simple membranous limb of saemicircular duct | The non-ampullary end of the lateral saemicircular duct that opens independently into the utricle. Synonym: crus membranaceum simplex ductus saemicircularis, simple membranous limb of saemicircular duct. (05 Mar 2000) |
| bone within a bone | <radiology> STOP heavy metal, S: sickle cell disease, T: Thorotrast, O: osteopetrosis, P: Paget's disease, heavy metals, hypervitaminosis D (12 Dec 1998) |
| acute reflex bone atrophy | Atrophy of bones, commonly of the carpal or tarsal bones, following a slight injury such as a sprain. See: causalgia, reflex sympathetic dystrophy. Synonym: acute reflex bone atrophy, posttraumatic osteoporosis, Sudeck's syndrome. Origin: L. English sweat (05 Mar 2000) |
| air-bone gap | The difference between the threshold for hearing acuity by bone conduction and by air conduction. (05 Mar 2000) |
| Albrecht's bone | A small bone between the basioccipital and basisphenoid. (05 Mar 2000) |
| allogeneic bone marrow transplant | <haematology, procedure> A bone marrow transplant using marrow collected from a matched healthy donor, usually a brother or sister. The risks associated with the transplant increase with age and 50 years of age is generally regarded as the upper limit. (13 Nov 1997) |
| alveolar bone | That portion of bone in either the maxilla or the mandible which surrounds and supports the teeth. (12 Dec 1998) |
| alveolar bone loss | The resorption of bone in the supporting structures of the maxilla or mandible as a result of periodontal disease. (12 Dec 1998) |
| alveolar supporting bone | alveolar process |
| amyloidosis: bone manifestations | <radiology> Joint pain without radiographic findings, osteoporosis, especially in axial skeleton, lytic lesions that destroy cortex and invade soft tissue, wrist, scaphoid and lunate lesions that may extend into the carpal tunnel, inducing the classic complaints of carpal tunnel syndrome amyloid arthropathy Differential diagnosis: pigmented villonodular synovitis, synovial chondromatosis, rheumatoid arthritis, TB (12 Dec 1998) |
| aneurysmal bone cyst | <radiology> ABC, 10 - 30 yrs, 75% before skeletal maturity, sites: long bones; also, flat bones Findings: metaphyseal if unfused, metaepiphyseal after fusion, lytic, expansile, thin, continuous rim, thin internal bony strands (12 Dec 1998) |