| accessory atrium | <cardiology, embryology> A congenital anomaly characterised by the presence in the atrium of a perforated muscular membrane which separates the atrium into upper and lower chambers. (12 Dec 1998) |
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| accessory auricles | Small, fleshy nodules or folds, sometimes with supporting cartilage, occasionally found along the margins of the embryonic branchial clefts. (05 Mar 2000) |
| accessory breast | A milk-secreting gland located elsewhere than at the normal place on the chest and existing in addition to the two usual mammae. Synonym: mamma accessoria, accessory breast, supernumerary mamma. (05 Mar 2000) |
| accessory canal | A channel leading from the root pulp laterally through the dentin to the periodontal tissue; may be found anywhere in the tooth root, but is more common in the apical third of the root. Synonym: lateral canal. (05 Mar 2000) |
| accessory cartilage | A sesamoid cartilage. (05 Mar 2000) |
| accessory cephalic vein | <anatomy, vein> A variable vein that passes along the radial border of the forearm to join the cephalic vein near the elbow. Synonym: vena cephalica accessoria. (05 Mar 2000) |
| accessory chromosome | A chromosome existing without its normal homologous chromosome; at the reduction division of gametogenesis an accessory chromosome is likely to be included in one daughter cell and not in the other, but may be lost completely by lagging behind on the equatorial plate. Synonym: monosome, odd chromosome, unpaired allosome, unpaired chromosome. (05 Mar 2000) |
| accessory cramp | <neurology> A wry neck, a contracted state of the cervical muscles, producing twisting of the neck and an unnatural position of the head. Origin: L. Tortus = twisted, collum = neck (18 Nov 1997) |
| accessory cuneate nucleus | A cell group lateral to the cuneate nucleus which receives posterior-root fibres corresponding to the proprioceptive innervation of the arm and hand; it projects to the cerebellum by way of the cuneocerebellar tract, and can be considered the upper-extremity equivalent of the thoracic nucleus. Synonym: nucleus cuneatus accessorius, external cuneate nucleus, lateral cuneate nucleus, Monakow's nucleus. (05 Mar 2000) |
| accessory flexor muscle of foot | <anatomy, muscle> Origin, by two heads from the lateral and medial borders of the inferior surface of the calcaneus; insertion, tendons of flexor digitorum longus; action, assists long flexor; nerve supply, lateral plantar. Synonym: musculus flexor accessorius, musculus quadratus plantae, accessory flexor muscle of foot, caro quadrata sylvii, musculus pronator pedis, plantar quadrate muscle, quadrate muscle of sole. (05 Mar 2000) |
| accessory flower part | <plant biology> Sepal and petal organs found on flowers. The sepals and petals are not essential for pollination but may aid in attracting insects or other organisms. (15 Jan 1998) |
| accessory fruit | <plant biology> A fruit, or group of fruits derived from one flower, in which the conspicuous, fleshy portion develops from the receptacle and is shed with the true fruit attached. (15 Jan 1998) |
| accessory gland | A small mass of glandular structure, detached from but lying near another and larger gland, to which it is similar in structure and probably in function. (05 Mar 2000) |
| accessory hemiazygos vein | <anatomy, vein> Formed by the union of the fourth to seventh left posterior intercostal veins, passes along the side of the bodies of the fifth, sixth, and seventh thoracic vertebrae, then crosses the midline behind the aorta, oesophagus, and thoracic duct, and empties into the azygos vein, sometimes in common with the hemiazygos vein. Synonym: vena hemiazygos accessoria, vena azygos minor superior. (05 Mar 2000) |
| accessory lacrimal glands | Small, compound, branched, tubular glands located in the middle part of the lid (Wolfring's glands, 1872, or Ciaccio's glands, 1874) and along the superior and inferior fornices of the conjunctival sac (Krause's glands, 1854). These accessory glands are just scattered scraps of lacrimal gland tissue; all of them produce the same kind of tears and debouch on to the conjunctival surface. Henle's and Baumgarten's "glands" are in fact not glands at all, but mere epithelial invaginations. Synonym: glandulae lacrimales accessoriae. (05 Mar 2000) |