| external occipital crest | A ridge extending from the external occipital protuberance to the border of the foramen magnum. Synonym: crista occipitalis externa, linea nuchae mediana. (05 Mar 2000) |
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| external occipital protuberance | A prominence about the centre of the outer surface of the squamous portion of the occipital bone, giving attachment to the ligamentum nuchae. Synonym: protuberantia occipitalis externa. (05 Mar 2000) |
| external opening of urethra | 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 ophthalmopathy | Any disease of the conjunctiva, cornea, or adnexa of the eye. (05 Mar 2000) |
| external ophthalmoplegia | Paralysis affecting one or more of the extrinsic eye muscles. Synonym: external ophthalmoplegia. (05 Mar 2000) |
| external os of uterus | The vaginal opening of the uterus. Synonym: ostium uteri, mouth of the womb, opening of uterus, orificium externum uteri, os uteri externum, ostium uteri externum. (05 Mar 2000) |
| external ovular transmigration | Direct ovular transmigration occurs when the ovum passes across the pelvic cavity. (05 Mar 2000) |
| external pacemaker | An artificial cardiac pacemaker whose electrodes for delivering rhythmical electrical stimuli to the heart are placed on the chest wall. (05 Mar 2000) |
| external phase | The medium or fluid in which a disperse is suspended. Synonym: continuous phase, dispersion medium, dispersion phase, external medium. (05 Mar 2000) |
| external pin fixation | In oral surgery, stabilization of fractures of the mandible, maxilla, or zygoma by pins or screws drilled into the bony part through the overlying skin and connected by a metal bar. Pin fixation by replacing the rigid metal bar connector with an acrylic bar adapted at the time of reduction of the fracture. (05 Mar 2000) |
| external pterygoid muscle | <anatomy, muscle> Origin, inferior head from lateral lamina of pterygoid process; superior head from infratemporal crest and adjacent greater wing of the sphenoid; insertion, into pterygoid pit of mandible and articular disk; action, brings jaw forward, opens jaw; nerve supply, nerve to lateral pterygoid from mandibular division of trigeminal. Synonym: musculus pterygoideus lateralis, external pterygoid muscle, musculus pterygoideus externus. (05 Mar 2000) |
| external pudendal arteries | Origin, femoral; distribution, skin over pubis, skin over penis and skin of scrotum or labium majus via anterior scrotal (labial) arteries; anastomoses, dorsal artery of penis or clitoris, posterior scrotal or labial arteries. Synonym: arteriae pudendae externae. (05 Mar 2000) |
| external pudendal veins | These correspond to the arteries of the same name; they empty into the great saphenous vein or directly into the femoral vein, and receive the superficial dorsal vein of the penis (clitoris) and the anterior scrotal (or labial) veins. Synonym: venae pudendae externae. (05 Mar 2000) |
| external pyocephalus | Meningeal suppuration. (05 Mar 2000) |
| external radiation | Radiation therapy that uses a machine located outside the body to aim high-energy rays at the cancer. (16 Dec 1997) |