| acute aortic dissection | <cardiology> A condition in which a weakened portion of the thoracic aorta begins to tear along the longitudinal axis of the vessel. Symptoms include sudden, severe chest pain that may radiate to the back accompanied by nausea, sweating and difficulty breathing. A common risk factor for this event is atherosclerotic vascular disease and-or hypertension. Advanced cases of syphilis (syphilitic aortitis) can also result in acute thoracic dissection as a complication of infection with Treponema pallidum. (27 Sep 1997) |
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| aortic dissection | A pathologic process, characterised by splitting of the media layer of the aorta, which leads to formation of a dissecting aneurysm. Classified according to location as follows: type I involves the ascending aorta, transverse arch, and distal aorta; type II is confined to the ascending aorta; type III extends distally in the descending aorta. (05 Mar 2000) |
| aortic dissection: aetiology | <radiology> Usually degenerative, due to aging, increased risk: hypertension, bicuspic aortic valve, aortic coarctation, pregnancy, connective tissue disorder (Marfan, Ehlers-Danlos), skeletal abnormalities (scoliosis, pectus), mycotic aneurysm, Takayasu (giant cell) arteritis, aortic laceration see also: classification (12 Dec 1998) |
| aortic dissection: classification | <radiology> DeBakey: I ascending aorta to arch with or without descending aorta (30%), II ascending aorta only (20%), III descending aorta to thoracic aorta (50%), Stanford: A involvement of ascending aorta (regardless of origin), B aortic arch and distal aorta see also: aetiology mnemomics: 1 A.D. (DeBakey), A = Ascending (12 Dec 1998) |
| axillary dissection | <procedure, surgery> Surgical removal of lymph nodes from the armpit. This tissue is then sent to the pathologist to determine if the breast cancer has spread outside of the breast. The number of nodes dissected varies during surgery. (02 Jan 1998) |
| radical neck dissection | The most commonly performed major operation for head and neck malignancies, most of which are squamous cell carcinomas. The neck is opened laterally, the majority of the sternocleidomastoid muscle is removed, as are the regional cervical lymph nodes, the jugular vein, the spinal accessory nerve, the submaxillary gland and most of the parotid gland. There are several modifications. (12 Dec 1998) |
| neck dissection | Surgery to remove lymph nodes and other tissues in the neck. (12 Dec 1998) |
| dissection | 1. The act of dissecting an animal or plant; as, dissection of the human body was held sacrilege till the time of Francis I. 2. The act of separating or dividing for the purpose of critical examination. 3. Anything dissected; especially, some part, or the whole, of an animal or plant dissected so as to exhibit the structure; an anatomical so prepared. Dissection wound, a poisoned wound incurred during the dissection of a dead body. Origin: Cf. F. Dissection. Source: Websters Dictionary (01 Mar 1998) |
| dissection tubercle | Dorsal tubercle of radius, a small prominence on the dorsal aspect of the distal end of the radius lateral to the groove for the extensor pollicis longus tendon; it serves as a trochlea or pulley for the tendon. Synonym: tuberculum dorsale, Lister's tubercle. (05 Mar 2000) |
| intramural oesophageal dissection | <radiology> Submucosal dissecting haematoma, haematemesis, chest pain, double-barreled lumen, Treatment: none (supportive) see: oesophageal trauma (12 Dec 1998) |
| adamantine membrane | The primary enamel cuticle, consisting of two extremely thin layers (the inner one clear and structureless, the outer one cellular), covering the entire crown of newly erupted teeth and subsequently abraded by mastication; it is evident microscopically as an amorphous material between the attachment epithelium and the tooth. Synonym: cuticula dentis, adamantine membrane, dental cuticle, membrana adamantina, Nasmyth's cuticle, Nasmyth's membrane, skin of teeth. (05 Mar 2000) |
| allantoid membrane | An embryonic diverticulum of the hindgut of reptiles, birds, and mammals; in man its blood vessels give rise to those of the umbilical cord. (12 Dec 1998) |
| alveolocapillary membrane | The pulmonary diffusion barrier. (05 Mar 2000) |
| alveolodental membrane | <anatomy> Fibrous connective tissue surrounding the root of a tooth that separates it from and attaches it to the alveolar bone. (12 Dec 1998) |
| anal membrane | The dorsal portion of the embryonic cloacal membrane after its division by the urorectal septum. Anterior atlanto-occipital membrane, the fibrous layer that extends from the anterior arch of the atlas to the anterior margin of the foramen magnum. Synonym: membrana atlanto-occipitalis anterior. (05 Mar 2000) |