| twin pregnancy | A pregnancy that may result from the fertilization of two separate ova or of a single ovum. See: twin. Synonym: bigeminal pregnancy. (05 Mar 2000) |
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| twin studies | Methods of detecting genetic aetiology in human traits. The basic premise of twin studies is that monozygotic twins, being formed by the division of a single fertilised ovum, carry identical genes, while dizygotic twins, being formed by the fertilization of two ova by two different spermatozoa, are genetically no more similar than two siblings born after separate pregnancies. (12 Dec 1998) |
| twin study | A method of detecting genetic causes in human traits and genetic factors in behaviour using sets of twins. (12 Dec 1998) |
| acute transverse myelitis | Acute inflammation and softening of the spinal cord; involves the entire thickness of the spinal cord but of limited longitudinal extent; multiple aetiologies. (05 Mar 2000) |
| caudal transverse fissure | A transverse fissure on the visceral surface of the liver between the caudate and quadrate lobes, lodging the portal vein, hepatic artery, hepatic nerve plexus, hepatic ducts, and lymphatic vessels. Synonym: caudal transverse fissure, portal fissure. (05 Mar 2000) |
| mesentery of transverse colon | See: mesocolon. (05 Mar 2000) |
| groove for transverse sinus | The groove on the inner surface of the occipital bone marking the course of the transverse sinus; the tentorium is attached to its margins. Synonym: sulcus sinus transversi, sulcus for transverse sinus. (05 Mar 2000) |
| middle transverse rectal fold | See: transverse rectal folds. (05 Mar 2000) |
| midgastric transverse sphincter | Angular sphincter, thickening of the circular muscular layer forming a proposed intermediate sphincter at the level of the angular notch of the stomach. While the thickening of the circular muscle may indicate the commencement of the pyloric antrum, true functional sphincteric activity distinct from the other peristaltic contractions of the stomach is not observed although some of these may in fact temporarily close off the antrum from the remainder of the stomach lumen. Synonym: antral sphincter, midgastric transverse sphincter, sphincter antri, sphincter intermedius, sphincter of antrum, sphincter of gastric antrum. (05 Mar 2000) |
| myelitis, transverse | Myelitis in which the functional effect of the lesions spans the width of the entire cord at a given level. (12 Dec 1998) |
| costal pit of transverse process | A facet on the transverse process of a vertebra for articulation with the tubercle of a rib. Synonym: fovea costalis processus transversi, costal pit of transverse process. (05 Mar 2000) |
| sulcus for transverse sinus | The groove on the inner surface of the occipital bone marking the course of the transverse sinus; the tentorium is attached to its margins. Synonym: sulcus sinus transversi, sulcus for transverse sinus. (05 Mar 2000) |
| superficial branch of the transverse cervical artery | <anatomy, artery> Branch of transverse cervical artery which accompanies the spinal accessory nerve on the deep surface of the trapezius muscle. Alternatively arises as a direct branch of the thyrocervical trunk, in which case it is called the superficial cervical artery. (05 Mar 2000) |
| superficial transverse metacarpal ligament | <anatomy> A thickening of the deep fascia in the most distal part of the (base) of the triangular palmar aponeurosis. Synonym: ligamentum metacarpale transversum superficiale, Gerdy's fibres, ligamentum natatorium. (05 Mar 2000) |
| superficial transverse metatarsal ligament | <anatomy> A thickening of the distal part (base) of the plantar aponeurosis, at the level of the heads of the metatarsal bones. Synonym: ligamentum metatarsale transversum superficiale. (05 Mar 2000) |