SPHERICAL EXCESS
\sfˈɛɹɪkə͡l ɛksˈɛs], \sfˈɛɹɪkəl ɛksˈɛs], \s_f_ˈɛ_ɹ_ɪ_k_əl ɛ_k_s_ˈɛ_s]\
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[Gr.] The portion of the surface of a sphere inclosed by arcs (each less than a semicircle) of three great circles is a Spherical triangle. The relations between the sides and angles of spherical triangles is the subject of Spherical excess geometry ; those between the trigonometrical functions of the sides and angles, of Spherical excess trigonometry. The excess of the sum of the three angles of a spherical triangle above two right angles is its Spherical excess. A Spherical excess segment is the part of a sphere cut off by a plane ; a Spherical excess sector is the part of a sphere inclosed within a conical surface whose vertex is at the centre.
By Henry Percy Smith
Word of the day
Olivopontocerebellar Atrophies
 group inherited disorders which share progressive ataxia combination with atrophy CEREBELLUM; PONS; inferior olivary nuclei. Additional features include RIGIDITY; NYSTAGMUS; RETINAL DEGENERATION; MUSCLE SPASTICITY; DEMENTIA; URINARY INCONTINENCE; OPHTHALMOPLEGIA. familial has an earlier onset (second decade) and may feature spinal cord atrophy. sporadic form tends to present in the fifth or sixth decade, is considered a clinical subtype MULTIPLE SYSTEM ATROPHY. (From Adams et al., Principles of Neurology, 6th ed, p1085)