锥体系是大脑皮层下行控制躯体运动的最直接路径。主要是管理骨骼肌的随意运动。锥体系主要由中央前回的锥体细胞的轴突所组成。这些纤维下行经内囊、大脑脚底、脑桥基底、延髓锥体等结构，其中中途终于脑干者称为皮质脑干束（又称皮质延髓束），继续下降进入脊髓者称为皮质脊髓束。 因此锥体系统（锥体系）包括皮质脊髓束，和皮质脑干束两部分。
然而，延髓症状在发病初期并不常见，两位有症状的患者几乎完全为锥体系受累表现另外两位患者无症状。
Bulbar symptoms, however, were infrequent at onset and two symptomatic patients had an almost pure pyramidal involvement. Two subjects were asymptomatic.
BD临床特征：进行性加重的智能衰退，定向力障碍及人格改变，假性延髓麻痹征，锥体系及锥体外系损害的表现。
The clinical features of BD was gradual decline of brainpower, orientation obstacle, characteristic changes, pseudobulbar palsy, manifestation of pyramidal and extrapyramidal motor system damages.
双层平板型斜放四角锥网架节点构造简单，受力合理，用钢量是四角锥体系网架中最小的一种形式，也是国内工程中应用较多的一种。
Double layer flat diagonal square pyramid grids has the advantages of being simple in formation, rational in member stressing and fairly economic of steel cost among square pyramid grids system.
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