| 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) |
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| 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 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) |
| accessory ligaments | Ligament's about a joint that are in addition to the articular capsule. They may lie within, or on the outside of the latter. (05 Mar 2000) |
| accessory meningeal branch of middle meningeal artery | <anatomy, artery> A branch of either the middle meningeal or maxillary artery in the infratemporal fossa and passing superiorly through the foramen ovale to supply the trigeminal ganglion, dura mater and inner table of bone. Synonym: ramus meningeus accessorius arteriae meningeae mediae. (05 Mar 2000) |
| accessory molecules | Cell surface adhesion molecules on T-cells that are involved in binding of one cell to another cell or in signal transduction, e.g., CD4. (05 Mar 2000) |
| accessory nasal cartilages | Variable small plates of cartilage located in the interval between the greater alar and lateral nasal cartilages. Synonym: cartilagines nasales accessoriae, sesamoid cartilages of nose. (05 Mar 2000) |
| accessory nerve | <anatomy, nerve> The accessory nerve enervates the sternocleidomastoid muscles and the trapezius muscles. Lesions of the eleventh result in drooping of the shoulder and inability to rotate the head away from the affected side. Synonym: cranial nerve XI. (27 Sep 1997) |
| accessory nerve lymph nodes | The nodes of the lateral deep cervical group that are located along the accessory nerve; their efferent vessels pass to the supraclavicular lymph nodes. Synonym: companion lymph nodes of accessory nerve, nodi lymphatici comitantes nervi accessorii. (05 Mar 2000) |
| accessory nerve trunk | Part of the accessory nerve formed within the cranial cavity by the union of the cranial and spinal roots, which then divides within the jugular foramen into internal and external branches, the former uniting with the vagus, the latter exiting the foramen as in independent branch which is commonly considered to be the accessory nerve. (05 Mar 2000) |