| back lens | <physics> In any compound lens (a lens system composed of more than one lens element), the last lens through which the light passes is called the back lens. It may be a single simple lens, a doublet, or triplet. See: front lens (05 Aug 1998) |
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| back mutation | <molecular biology> A mutation that causes a mutant gene to revert to its original wild-type base sequence. Compare: forward mutation. (09 Oct 1997) |
| back of foot reflex | The foot being firmly supported on its inner side, a sharp tap on the dorsal tendons causes extension of the second to the fifth toes. Synonym: back of foot reflex, dorsum of foot reflex. (05 Mar 2000) |
| back pain | A continuous pain located in the back, usually below the cervical level. For lower back pain or pain in the lumbar region, low back pain is available. (12 Dec 1998) |
| back pain, low | Symptoms in the low back can relate to the bony lumbar spine, discs between the vertebrae, ligaments around the spine and discs, spinal cord and nerves, muscles of the low back, internal organs of the pelvis and abdomen, and the skin covering the lumbar area. The low back, or lumbar area, functions in structural support, movement, and protection of certain body tissue. (12 Dec 1998) |
| back pressure | Pressure exerted upstream in the circulation as a result of obstruction to forward flow, as when congestion in the pulmonary circulation results from stenosis of the mitral valve or failure of the left ventricle. (05 Mar 2000) |
| back-pressure renal atrophy | <radiology> Caliectasis without obstruction, due to repeated episodes of obstruction, gradual loss of renal pyramids (12 Dec 1998) |
| back teeth | All teeth posterior to the canines. (05 Mar 2000) |
| broadest muscle of back | <anatomy, muscle> Origin, spinous processes of lower five or six thoracic and the lumbar vertebrae, median ridge of sacrum, and outer lip of iliac crest; insertion, with teres major into posterior lip of bicipital groove of humerus; action, adducts arm, rotates it medially, and extends it; nerve supply, thoracodorsal. Synonym: musculus latissimus dorsi, broadest muscle of back. (05 Mar 2000) |
| pain, back | Symptoms in the low back can relate to the bony lumbar spine, discs between the vertebrae, ligaments around the spine and discs, spinal cord and nerves, muscles of the low back, internal organs of the pelvis and abdomen, and the skin covering the lumbar area. (12 Dec 1998) |
| regions of back | The topographical regions of the back of the trunk, including the vertebral region, sacral region, scapular region, infrascapular region, and lumbar region. Synonym: regiones dorsales. (05 Mar 2000) |
| muscles of the back | The muscles of the back in general, including those attaching the shoulder girdle to the trunk posteriorly, the posterior serratus muscles, and the erector spinae. Synonym: musculi dorsi, dorsal muscles. (05 Mar 2000) |
| poker back | Arthritis and osteitis deformans involving the spinal column; marked by nodular deposits at the edges of the intervertebral disks with ossification of the ligaments and bony ankylosis of the intervertebral articulations, it results in a rounded kyphosis with rigidity. Synonym: Bechterew's disease, poker back, Strumpell's disease. (05 Mar 2000) |
| hog's-back | <geology> A hogback. Source: Websters Dictionary (01 Mar 1998) |
| push-back procedure | A surgical manoeuvre designed to reposition the soft palate posteriorly and reestablish velopharyngeal competence. (05 Mar 2000) |