| Bell's palsy | A condition that involves the facial nerve (VII cranial nerve) and results in the paralysis of one side of the face. Bell's (facial nerve palsy) can be differentiated from a central (stroke) deficit by the inability to raise the eyebrow on the affected side. (27 Sep 1997) |
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| Bell's phenomenon | A patient with peripheral facial paralysis cannot close the eyelids of the affected side without at the same time moving the eyeball upward and outward. (05 Mar 2000) |
| Bell's respiratory nerve | <anatomy, nerve> Arises from the fifth, sixth, and seventh cervical nerves (roots of brachial plexus), descends the neck behind the brachial plexus, and is distributed to the serratus anterior muscle; it is somewhat unusual in that it courses on the superficial aspect of the muscle is supplies; its paralysis results in "winged scapula". Synonym: nervus thoracicus longus, Bell's respiratory nerve, external respiratory nerve of Bell, posterior thoracic nerve. (05 Mar 2000) |
| Bell's spasm | Involuntary twitching of the facial muscles, sometimes unilateral. Synonym: Bell's spasm, convulsive tic, facial spasm, histrionic spasm, mimic convulsion, mimic spasm, mimic tic, palmus, prosopospasm. (05 Mar 2000) |
| bell stage | Third stage of tooth development, wherein the cells form the inner enamel epithelium, the stratum intermedium, the stellate reticulum, and the outer enamel epithelium; the enamel organ assumes a bell shape. (05 Mar 2000) |
| syndrome, martin-bell | Better known as the fragile X syndrome, the most common heritable form of mental retardation. Fragile x syndrome is due to mutation (changes) at the fragile x site and so perforce is x-linked (carried on the x chromosome). Although it is usually more severe in males than females, the syndrome is due to a dynamic mutation (a trinucleotide repeat) that can change in length and hence in severity from generation to generation, from person to person, and even within a given person. The fragile x syndrome is known as the martin-bell syndrome in honor of their discovery of it in 1943. (12 Dec 1998) |
| external respiratory nerve of Bell | <anatomy, nerve> Arises from the fifth, sixth, and seventh cervical nerves (roots of brachial plexus), descends the neck behind the brachial plexus, and is distributed to the serratus anterior muscle; it is somewhat unusual in that it courses on the superficial aspect of the muscle is supplies; its paralysis results in "winged scapula". Synonym: nervus thoracicus longus, Bell's respiratory nerve, external respiratory nerve of Bell, posterior thoracic nerve. (05 Mar 2000) |
| active metal | <chemistry> Any very reactive metal, such as magnesium or sodium, most are located in the first two columns of the periodic table. (15 Jan 1998) |
| alkali earth metal | See: alkaline earth elements. (05 Mar 2000) |
| alkali metal | <chemistry> Any of the highly reactive metals (such as sodium or potassium) found in the first column of the periodic table, these metals act as bases. (13 Nov 1997) |
| Babbitt metal | An alloy of antimony, copper, and tin; used occasionally in dentistry. (05 Mar 2000) |
| base metal | A metal that is readily oxidised; e.g., iron, copper. (05 Mar 2000) |
| rare earth metal | Those elements with atomic numbers 57-71 which closely resemble one another chemically and were once difficult to separate from one another. Synonym: rare earth elements. Origin: Lanthanum, first element of the series (05 Mar 2000) |
| central metal ion | <chemistry> The metal ion to which the ligands are attached at the centre of a coordination complex. (09 Oct 1997) |
| void metal composite | A porous metal structure that enables tissue growth within the openings to establish long-term attachment between prosthesis and tissue. (05 Mar 2000) |