| CM | California mastitis [test]; calmodulin; capreomycin; carboxymethyl; cardiac murmur; cardiac muscle; ... |
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| LM | lactic acid mineral [medium]; lactose malabsorption; laryngeal mask; laryngeal muscle; lateral malle... |
| MG | Marcus Gunn [pupil]; margin; medial gastrocnemius [muscle]; membranous glomerulonephritis; menopausa... |
| MS | Maffuci syndrome; maladjustment score; mandibular series; Marfan syndrome; Marie-Strumpell [syndrome... |
| PM | after death (Lat. post mortem); after noon [Lat. post meridiem]; mean pressure; pacemaker; pantomogr... |
| pyramidal radiation | Corticospinal fibres passing from the cortex into the pyramid. Synonym: radiatio pyramidalis. (05 Mar 2000) |
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| pyramidal tract | A massive bundle of fibres originating from pyramidal cells of various sizes in the fifth layer of the precentral motor (area 4), the premotor area (area 6), and to a lesser extent from the postcentral gyrus. Cells of origin in area 4 include the gigantopyramidal cells of Betz. Fibres from these cortical regions descend through the internal capsule, the middle third of the crus cerebri, and the ventral part of the pons to emerge on the ventral surface of the medulla oblongata as the pyramis. Continuing caudally, most of the fibres cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord as the lateral pyramidal tract, which distributes its fibres throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. In the (extremity-related) spinal cord enlargements, fibres also pass directly to motoneuronal groups that innervate distal extremity muscles subserving particular hand-and-finger or foot-and-toe movements. The uncrossed fibres form a small bundle, the anterior pyramidal tract, which descends in the anterior funiculus of the spinal cord and terminates in synaptic contact with interneurons in the medial half of the anterior horn on both sides of the spinal cord. Interruption of the pyramidal tract at or below its cortical origin causes impairment of movement in the opposite body-half, especially severe in the arm and leg; characterised by muscular weakness, spasticity and hyperreflexia, and a loss of discrete finger and hand movements. Babinski's sign is associated with this condition of hemiplegia. Synonym: tractus corticospinalis, tractus pyramidalis, corticospinal tract. (05 Mar 2000) |
| pyramidal tractotomy | May be mesencephalic (pedunculotomy or crusotomy), medullary (medullary pyramidotomy), or spinal (spinal pyramidotomy). (05 Mar 2000) |
| direct pyramidal tract | Uncrossed fibres forming a small bundle in the pyramidal tract. See: pyramidal tract. Synonym: tractus corticospinalis anterior, tractus pyramidalis anterior, anterior corticospinal tract, anterior pyramidal fasciculus, direct pyramidal tract, fasciculus corticospinalis anterior, fasciculus pyramidalis anterior, Turck's bundle, Turck's column, Turck's tract. (05 Mar 2000) |
| lateral pyramidal fasciculus | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| lateral pyramidal tract | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| abdominal external oblique muscle | <anatomy, muscle> Origin, fifth to twelfth ribs; insertion, anterior half of lateral lip of iliac crest, inguinal ligament, and anterior layer of the rectus sheath; action, diminishes capacity of abdomen, draws thorax downward; nerve supply, thoracoabdominal nerves. Synonym: musculus obliquus externus abdominis, abdominal external oblique muscle. (05 Mar 2000) |
| abdominal internal oblique muscle | <anatomy, muscle> Origin, iliac fascia deep to lateral part of inguinal ligament, anterior half of crest of ilium, and lumbar fascia; insertion, tenth to twelfth ribs and sheath of rectus; some of the fibres from inguinal ligament terminate in the conjoint tendon; action, diminishes capacity of abdomen, flexes lumbar vertebral column (bends thorax forward); nerve supply, lower thoracic. Synonym: musculus obliquus internus abdominis, abdominal internal oblique muscle. (05 Mar 2000) |
| abdominal muscle deficiency syndrome | <syndrome> Congenital absence (partial or complete) of abdominal muscles, in which the outline of the intestines is visible through the protruding abdominal wall; in males, genitourinary anomalies (urinary tract dilation and cryptorchidism) are also found; genetics unclear. (05 Mar 2000) |
| abductor digiti minimi muscle of foot | Origin, lateral and medial processes of calcanean tuberosity; insertion, lateral side of proximal phalanx of fifth toe; action, abducts and flexes little toe; nerve supply, lateral plantar nerve. Synonym: musculus abductor digiti minimi pedis, abductor muscle of little toe, musculus abductor digiti quinti. (05 Mar 2000) |
| abductor digiti minimi muscle of hand | Origin, pisiform bone and pisohamate ligament; insertion, medial side of base of proximal phalanx of the little finger; action, abducts and flexes little finger; nerve supply, ulnar. Synonym: musculus abductor digiti minimi manus, abductor muscle of little finger, musculus abductor digiti quinti. (05 Mar 2000) |
| abductor muscle | <anatomy> Any muscle used to pull a body part away from the midline of the body. For example, the abductor leg muscles serve to spread the legs. The opposite of abductor is adductor. (12 Dec 1998) |
| abductor muscle of great toe | <anatomy, muscle> Origin, medial process of calcaneal tuberosity, flexor retinaculum, and plantar aponeurosis; insertion, medial side of proximal phalanx of great toe; action, abducts great toe; nerve supply, medial plantar. Synonym: musculus abductor hallucis, abductor muscle of great toe. (05 Mar 2000) |
| abductor muscle of little finger | Origin, pisiform bone and pisohamate ligament; insertion, medial side of base of proximal phalanx of the little finger; action, abducts and flexes little finger; nerve supply, ulnar. Synonym: musculus abductor digiti minimi manus, abductor muscle of little finger, musculus abductor digiti quinti. (05 Mar 2000) |
| abductor muscle of little toe | Origin, lateral and medial processes of calcanean tuberosity; insertion, lateral side of proximal phalanx of fifth toe; action, abducts and flexes little toe; nerve supply, lateral plantar nerve. Synonym: musculus abductor digiti minimi pedis, abductor muscle of little toe, musculus abductor digiti quinti. (05 Mar 2000) |