| lower motor neuron | Clinical term used to indicate the final motor neuron's that innervate the skeletal muscles; distinguished from upper motor neuron's of the motor cortex that contribute to the pyramidal or corticospinal tract. See: motor neuron. (05 Mar 2000) |
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| lower motor neuron dysarthria | Dysarthria caused by dysfunction of the motor nuclei and the lower pons or medulla, or other neural connections, central and peripheral to the muscles of articulation. (05 Mar 2000) |
| lower motor neuron lesion | Injury to motor cells in the brainstem or spinal cord, or of the axons derived from them. (05 Mar 2000) |
| lower nephron nephrosis | An obsolete term for acute tubular necrosis. (05 Mar 2000) |
| lower nodal extrasystole | An obsolete term for a nodal extrasystole supposed to arise from the lower part of the A-V node, recognised in the electrocardiogram by the retrograde P wave that follows the QRS complex. (05 Mar 2000) |
| lower oesophageal sphincter | <anatomy> A muscular sphincter located at the junction of the oesophagus and the stomach. On closure the lower oesophageal sphincter prevents the back wash (reflux) of stomach acid into the oesophagus where it may damage the mucosa. See: gastrooesophageal reflux disease. (16 Mar 1998) |
| lower respiratory tract | <anatomy> The trachea, bronchi, and lungs. (09 Oct 1997) |
| lower respiratory tract smear | A group of cytologic specimens containing material from the lower respiratory tract and consisting mainly of sputum (spontaneous, induced) and material obtained at bronchoscopy (aspirated, lavaged, brushed); used for cytologic study of cancer and other diseases of the lungs. Synonym: bronchoscopic smear, sputum smear. (05 Mar 2000) |
| Lower, Richard | <person> English anatomist and physiologist, 1631-1691. See: Lower's ring, Lower's tubercle. (05 Mar 2000) |
| lower segment cesarian section | A Cesarian section in which the surgical incision (cut) is made in the lower segment of the uterus. (12 Dec 1998) |
| Lower's ring | One of four fibrous rings that surround atrioventricular and arterial orifices of the heart, providing attachment for the valve leaflets and maintaining patency of the orifice. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium. Synonym: annulus fibrosus cordis, annulus fibrosus, coronary tendon, fibrous ring, Lower's ring. (05 Mar 2000) |
| Lower's tubercle | The slight projection on the wall of the right atrium between the orifices of the venae cavae. Synonym: tuberculum intervenosum, Lower's tubercle. (05 Mar 2000) |
| lower uterine segment | The inferior portion or isthmus of the uterus, the lower extremity of which joins with the cervical canal and, during pregnancy, expands to become the lower part of the uterine cavity. (05 Mar 2000) |
| lower uterine segment cesarean section | A cesarean section in which the uterus is entered in its lower segment by a transperitoneal approach. (05 Mar 2000) |