| head kidney | 1. The definitive excretory organ of primitive fishes. Synonym: head kidney. 2. In the embryos of higher vertebrates, a vestigial structure consisting of a series of tortuous tubules emptying into the cloaca by way of the primary nephric duct; in the human embryo, the pronephros is a very rudimentary and temporary structure, followed by the mesonephros and still later by the metanephros. Synonym: forekidney, primordial kidney. Origin: pro-+ G. Nephros, kidney (05 Mar 2000) |
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| head lice | Small parasitic insects that can cause a itching red rash to the skin of the waist, shoulders, armpits, neck and pubic area. Commonly spread from person-to-person via close contact. The eggs (nits) of head lice can be mistaken for dandruff, but they are adherent to the hair shafts. Symptoms include itching, eggs visible on hair shafts and lice on hair, scalp or clothing. Treatment requires the use of a special prescription insecticide (Kwell) shampoo and/or lotion. (27 Sep 1997) |
| head mirror | A circular concave mirror attached to a head band, used to project a beam of light into a cavity, such as the nose or larynx, for purposes of examination and permitting binocular vision. (05 Mar 2000) |
| head movements | Voluntary or involuntary motion of head that may be relative to or independent of body; includes animals and humans. (12 Dec 1998) |
| head-nodding | Head movements associated with congenital nystagmus, spasmus nutans, and miner's nystagmus. Synonym: head tremors. (05 Mar 2000) |
| head nurse | A nurse administratively responsible for a designated hospital unit on a 24 hour basis. Synonym: charge nurse. (05 Mar 2000) |
| head of epididymis | The upper and larger extremity of the epididymis. Synonym: caput epididymidis, caput epididymis, globus major. (05 Mar 2000) |
| head of femur | The hemispheric articular surface at the upper extremity of the thigh bone. Synonym: caput ossis femoris, caput femoris, head of thigh bone. (05 Mar 2000) |
| head of fibula | The superior extremity of the fibula, which articulates by a facet with the undersurface of the lateral condyle of the tibia. Synonym: caput fibulae, upper extremity of fibula. (05 Mar 2000) |
| head of humerus | The upper rounded extremity fitting into the glenoid cavity of the scapula. Synonym: caput humeri. (05 Mar 2000) |
| head of malleus | The rounded portion of the malleus articulating with the body of the incus. Synonym: caput mallei. (05 Mar 2000) |
| head of mandible | The expanded articular portion of the condylar process of the mandible. Synonym: caput mandibulae. (05 Mar 2000) |
| head of metacarpal bone | The expanded distal end of a metacarpal that articulates with the proximal phalanx of the same digit. Synonym: caput ossis metacarpalis. (05 Mar 2000) |
| head of metatarsal bone | The expanded distal end of a metatarsal bone that articulates with the proximal phalanx of the same digit. Synonym: caput ossis metatarsalis. (05 Mar 2000) |
| head of pancreas | That portion of the pancreas lying in the concavity of the duodenum. Synonym: caput pancreatis. (05 Mar 2000) |