| HHT | head halter traction; hereditary hemorrhagic telangiectasia; heterotopic heart transplantation; homo... |
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| HI | half-scan with interpolation; head injury; health insurance; hearing impaired; heart infusion; hemag... |
| HIR | head injury routine |
| H&N | head and neck |
| HNS | head and neck surgery; home nursing supervisor |
| frontal region of head | The surface region of the head corresponding to the outlines of the frontal bone. Synonym: regio frontalis capitis. (05 Mar 2000) |
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| ligament of head of femur | A flattened ligament that passes from the fovea in the head of the femur to the borders of the acetabular notch (transverse acetabular ligament); developmentally, an artery passes to the head of the femur with the ligament which may or may not persist into adulthood; the ligament does not contribute to the integrity of the joint or control movements there. Synonym: ligamentum capitis femoris, ligamentum teres femoris, round ligament of femur. (05 Mar 2000) |
| little head of humerus | The small rounded eminence on the lateral half of the distal end of the humerus for articulation with the radius. Synonym: capitulum humeri, capitellum, little head of humerus. (05 Mar 2000) |
| long head | The head that has the more proximal origin. Nomina Anatomica lists long heads (caput longum...) of the following: 1) biceps brachii muscle (... Musculi bicipitis brachii ); 2) biceps femoris muscle (... Musculi bicipitis femoris ); 3) triceps brachii muscle (... Musculi tricipitis brachii ). Synonym: caput longum. (05 Mar 2000) |
| long head of triceps | <anatomy, muscle> Origin, infraglenoid tuberosity of scapula; insertion, posterior and upper olecranon and fascia of the forearm; action, extends and adducts arm. (06 Mar 2000) |
| long muscle of head | <anatomy, muscle> Origin, anterior tubercles of transverse processes of third to sixth cervical vertebrae; insertion, basilar process of occipital bone; action, twists or flexes neck anteriorly; nerve supply, cervical plexus. Synonym: musculus longus capitis, long muscle of head, musculus rectus capitis anticus major. (05 Mar 2000) |
| adhesion phenomenon | A phenomenon manifested by the adherence of antigen-antibody-complement complex to "indicator cells" (microorganisms, platelets, leukocytes, or erythrocytes), the reaction being sensitive and specific for the antigen and antibody in the complex. Synonym: erythrocyte adherence phenomenon, immune adherence phenomenon, red cell adherence phenomenon. (05 Mar 2000) |
| AFORMED phenomenon | As induced pulsus alternans progresses, a state in which alternating heart depolarisations fail to eject any blood, thus allowing longer diastolic filling; the subsequent beat is then able to produce a significant ejection; at high rates the cardiac minute volume and blood pressure may appear normal. Origin: Alternating, failure of response, mechanical, to electrical depolarisation (05 Mar 2000) |
| all-or-nothing phenomenon | <physiology> Refers to the phenomenon where the strength of a nerve impulse is not dependent on the strength of the stimulus. Instead, there is a threshold level of stimulus strength that must be reached before the nerve will fire an impulse (at full capacity). Below the threshold, the nerve will not fire at all. <cardiology> It also refers to the same phenomenon observed in the heart muscle, which will either contract fully or not at all. <psychology> In studies of behaviour, it refers to the same phenomenon where a behavioural stimulus will either produce a complete response or no response at all. Also called all-or-nothing principle, all-or-none law, all-or-none responsiveness, etc. (15 Nov 1997) |
| Anrep phenomenon | Homeometric autoregulation of the heart whereby cardiac performance improves as the afterload (aortic pressure) is increased. (05 Mar 2000) |
| aqueous influx phenomenon | The filling of the aqueous vein, which normally carries blood and aqueous, with aqueous, when the junction of the aqueous vein and the recipient vein is partially occluded. Synonym: Ascher's aqueous influx phenomenon. (05 Mar 2000) |
| Arias-Stella phenomenon | Focal, unusual, decidual changes in endometrial epithelium, consisting of intraluminal budding, and nuclear enlargement and hyperchromatism with cytoplasmic swelling and vacuolation; may be associated with ectopic or uterine pregnancy. Synonym: Arias-Stella effect, Arias-Stella reaction. (05 Mar 2000) |
| arm phenomenon | In tetany, spasm both of the extensor muscles of the knee and of the calf muscles when the extended leg is flexed at the hip. Synonym: leg phenomenon, Pool-Schlesinger sign, Schlesinger's sign. In tetany, contraction of the arm muscles following the stretching of the brachial plexus by elevation of the arm above the head with the forearm extended, resembles the contraction resulting from stimulation of the ulnar nerve. Synonym: arm phenomenon. (05 Mar 2000) |
| Arthus phenomenon | A form of immediate hypersensitivity resulting in erythema, oedema, haemorrhage, and necrosis observed in rabbits after injection of antigen to which the animal has already been sensitised and has specific IgG antibodies. The reaction is caused by the inflammation that results from the deposition of antigen-antibody complexes in tissue spaces and in blood vessel walls that activate complement, most of the damage seemingly being due to the polymorphonuclear leukocytes that phagocytise the deposits and release lysosomal enzymes. The phenomenon, described by Arthus, was in rabbits, but similar reactions (Arthus-type reactions) are observed in guinea pigs, rats, and dogs, as well as in humans. See: Arthus reaction. Synonym: Arthus reaction. (05 Mar 2000) |
| Ascher's aqueous influx phenomenon | The filling of the aqueous vein, which normally carries blood and aqueous, with aqueous, when the junction of the aqueous vein and the recipient vein is partially occluded. Synonym: Ascher's aqueous influx phenomenon. (05 Mar 2000) |