trabeation (trabeashon)

[ trace a pair of longitudinal cartilaginous bars, at the base of the skull, in advance of the end of the notochord and of the para chordal cartilage, inclosing the pituitary space which afterward becomes the sella turcica; in the human embryo, one of the lateral trabecules of Rathke. They are constant in embryos of a large series of vertebrates, and persistent in adults of some. More fully called trabeculæ cranii. See cuts under chondrocranium and Crotal us. 4. One of the calcareous plates or pieces which connect the dorsal and ventral walls of the corona in echinoderms.-5. One of the fleshy columns, or columnæ carneæ, in the ventricle of the heart, to which the chordæ tendinese are attached: more fully called trabecula carnea.-6. In entom., one of the pair of movable appendages on the head, just in front of the antennæ, of some mallophagous insects, or bird-lice, as those of the genus Docophorus. They have been supposed to represent the rudiments of a second pair of antennæ. Also trabeculus. - Rathke's trabeculæ. See def. 3.- Trabecula carnea. See def. 5.- Trabecula cerebri, the corpus callosum, or trabs cerebri. - Trabecula cinerea, the middle, soft, or gray commi ure of the cerebrum. - Trabeculæ cranii. See def. 3. Trabeculæ of the spleen, connective-ti ue lam inæ pa ing inward from the tunica propria, traversing in all directions the splenic pulp, and supporting it. - Trabecula tenuis, a name provisionally applied to a slender and apparently fibrous filament which, in the heart of the cat, spans the right ventricle near its apex, with its septal end springing from an independent little elevation, and its lateral end attached to the base of a column a carnea. Wilder and Gage, Anat. Tech., p. 330. trabecular (trā-bek'u-lär), a. [ [ trabecular ism (tra-bek ū-lar-izm), n. becular + -ism.] In an at., a coarse reticulation, or cro -barred condition, of any ti ue. trabeculate (tra-bek'ū-lāt), a. [