| external saphenous nerve | <anatomy, nerve> A branch of the tibial nerve which supplies sensory innervation to parts of the lower leg and foot. (12 Dec 1998) |
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| external secretion | A substance formed by a cell and transported outside the cell walls as a means of ridding the cell of the substance or as a messenger to affect the function of other cells. (05 Mar 2000) |
| external semilunar fibrocartilage | A flat disc-shaped ligament which stabilises and supports the outer aspect of the knee joint. Not as commonly injured as the medical meniscus ligament in knee sprains. (27 Sep 1997) |
| external sheath of optic nerve | <anatomy, nerve> The outer sheath around the optic nerve, continuous with the dura mater. Synonym: vagina externa nervi optici, dural sheath of optic nerve. (05 Mar 2000) |
| external sphincter muscle of anus | A fusiform ring of striated muscular fibres surrounding the anus, attached posteriorly to the coccyx and anteriorly to the central tendon of the perineum; it is subdivided, often indistinctly, into a subcutaneous part, a superficial part and a deep part for descriptive purposes. Synonym: musculus sphincter ani externus, external sphincter muscle of anus. (05 Mar 2000) |
| external sphincterotomy | Transurethral incision of external urethral sphincter. (05 Mar 2000) |
| external spiral sulcus | A concavity in the outer wall of the cochlear duct between the prominentia spiralis and the spiral organ. Synonym: sulcus spiralis externus. (05 Mar 2000) |
| external squint | <clinical sign> The outward or temporal deviation of an eye. (27 Sep 1997) |
| external strabismus | An obsolete term for exotropia. (05 Mar 2000) |
| external surface | The outer convex surface of either the frontal or the parietal bone. Synonym: facies externa. (05 Mar 2000) |
| external surface of frontal bone | The convex outer surface of the frontal bone. Synonym: facies externa ossis frontalis. (05 Mar 2000) |
| external surface of parietal bone | The convex outer surface of the parietal bone. Synonym: facies externa ossis parietalis. (05 Mar 2000) |
| external traction | A pulling force created by using fixed anchorage (e.g., a headcap or bed frame) outside the oral cavity; principally used in the management of midfacial fractures. (05 Mar 2000) |
| external urethral orifice | The slitlike opening of the urethra in the glans penis, the external orifice of the urethra (in the female) in the vestibule, usually upon a slight elevation, the papilla urethrae. Synonym: ostium urethrae externum, external opening of urethra, meatus urinarius, orificium urethrae externum. (05 Mar 2000) |
| external urethral sphincter | Origin, ramus of pubis; insertion, with fellow in median raphe behind and in front of urethra; action, constricts membranous urethra; nerve supply, pudendal. Synonym: musculus sphincter urethrae, external urethral sphincter, Guthrie's muscle, musculus compressor urethrae, musculus constrictor urethrae, musculus sphincter urethrae membranaceae, sphincter muscle of urethra, Wilson's muscle. (05 Mar 2000) |