| lower lid | The inferior, smaller and less mobile of the two eyelids; a check ligament from the inferior rectus muscle extends into it, pulling the lid inferiorly when the gaze is directed downward. Synonym: palpebra inferior, lower lid. (05 Mar 2000) |
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| lower limb | The hip, thigh, leg, ankle, and foot. Synonym: membrum inferius, inferior limb, lower extremity, pelvic limb. (05 Mar 2000) |
| lower lip | The muscular fold bounding the opening of the mouth inferiorly. Synonym: labium inferius oris. (05 Mar 2000) |
| lower lobe of lung | It is located below and behind the oblique fissure and contains five bronchopulmonary segments: superior, medial basal, anterior basal, lateral basal, and posterior basal. Synonym: lobus inferior pulmonis, lower lobe of lung. (05 Mar 2000) |
| 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) |
| 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, 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) |