sphenographist (sfenografist)

[ II. n. 1. In crystal . , a wedge-shaped crystalline form contained under four equal isosceles triangles. It is the hemihedral form of the square pyramid of the tetragonal system.-2. In an at . , a large and important compound bone of the skull: so called from its shape and con a. nections in man. The cranial articulations are with the occipital, temporal, parietal, frontal, and ethmoid; the facial, with the vomer, malar, palate, and sometimes the superior maxillary. It has a solid median and inferior body, and bears on each side two pairs of wings, greater and le er, separated by the sphenoidal fi ure from each oth er. It is a collec tion of bones, not a single bone, its composition including, IMG:content-1716.png:[blocks in formation] Human Sphenoid Bone, from above. a, a, ali sphenoid, or greater wing, the lower letter a pointing to its continuation as the external pterygoid proce ; bs, bas i sphenoid, or main body of the bone, bs pointing to the sphenoccipital articulation; pc, post clinoid proce es, bounding the pituitary fo a or sella Turcica behind; As, presphe noid, or fore part of the body of the bone; 0, or bito sphenoid, or le er wing; A, internal pterygoid proce ; 1, optic foramen; 2, sphenoidal fi ure, or foramen lacerum anterius; 3, foramen rotundum; 4, foramen ovale; 5, groove for internal carotid artery, or cavernous groove. in man and the mammals generally, ( a ) a bas i sphenoid, the principal posterior part of the body of the bone, bearing (b) the ali sphenoids, the pair of greater wings, these elements forming with the parietal bones the second or parietal segment of the cranium; (c) the pre sphenoid, the le er anterior moiety of the body of the bone, bearing (d) the or bito sphenoids, the pair of le er wings, or pro ce es of In gra i as, these forming with the frontal bones the third or frontal cranial segment; (e) a pair of pterygoid bones, the so-called internal pterygoid proce es; (f) a pair of spongy bones, the sphenoturbinals. The development of the human sphenoid is from 14 centers of o ification, 8 in the post sphenoid division, and 6 in the pre sphenoid division. Below mammals, in Sauropsida (birds and reptiles), the sphenoid is simplified by subtraction of the pterygoids, which then form permanently distinct bones, and complicated by the addition of other elements, especially an underlying membrane-bone called the para sphenoid. In Ichthyopsid a (amphibians and fishes) further and very great modifications occur. To the sphenoid of man are attached twelve pairs of muscles. sphenoidal (sfē-noi'dal), a. [ suture with the coronal suture. It often contains a Wormian bone.- Sphenoidal hemihedrism. See hem i hedrism. - Sphenoidal proce . See proce . - Sphenoidal rostrum. (a) The beak, or a beak-like part, of the sphenoid bone. In man it is a vertical ridge upon which the vomer rides, forming the sphenovomerine or schindylesis. (b) In birds, a rostrate part of the skull which appears to be chiefly, if not entirely, developed from the parasphenoid. - Sphenoidal septum. See septum sphenoid ale, under septum. - Sphenoidal sinuses. See sinus. Sphenoidal spongy bones, the sphenoturbinals. sphenoides (sfē-noi'dēz), n. [NL., sphenoidofrontal (sfē-noi"do-fron'tal), a. In craniom., noting the ratio of the minimum sphenoidal diameter of the skull to the mini mum frontal diameter. sphenoidoparietal (sfē-noi dō-pā-ri'e-tal), a. In craniom., noting the ratio of the minimum sphenoidal diameter of the skull to the maximum parietal diameter. sphenomalar (sfē-nō-māʻlär), a. [ IMG:content-1717.png:[blocks in formation] genus Sphenopteris. Sphenopteris (sfe-nop'te-ris), n. [NL. (Brongniart, 1822), a fern: see Pteris.] A A genus of fo il ferns. very widely distributed and very abundant, especially in the (Carboniferous) coal-measures, but ranging from the Devonian to the Middle Cretaceous. "These are elegant ferns, very numer cost at us. sphenonchus (sfē-nong'kus), n.; pl. sphenonchi (-ki). [NL., spheno-orbital, spheno-orbitar (sfe-nō-ôr'bital, -tär), a. Same as sphenorbital. sphenopalatine (sfe-no-pal'a-tin), a. [ Same as nasopalatine nerve (which see, under nasopala tine). - Sphenopalatine artery, a branch arising from the third or sphenomaxillary portion of the internal maxillary artery. It pa es through the sphenopalatine foramen into the cavity of the nose, and is distributed to the nasal mucous membrane and the membranes of the antrum, ethmoid, and sphenoid cells. Also called nasal artery.-Sphenopalatine foramen, ganglion, notch. See the nouns.-Sphenopalatine nerves, two small branches of the superior maxillary nerve to the sphenopalatine or Meckel's ganglion. - Sphenopalatine vein, a small vein entering the pterygoid plexus.