背景：为了了解腕部和手部背侧的成人伸肌10-dons数量的相当大的变化。
方法：我们检查了30例胎龄7-39周和冠臀长度22-323mm的人类胎儿的组织学切片。
结果：在腕骨层面，更早或更小的胎儿表现出更简单的配置，更少的肌腱滑移，而较晚或更大的胎儿有更多的肌腱滑移，在数量和地形关系上有很大差异。早期指伸肌到中指和无名指的肌腱滑动始终为1或2，但晚期为7或更多。指伸肌到小鳍的肌腱无法与腕骨水平的其他肌腱区分开。在腕骨元骨水平,然而,它从无名指肌腱向指伸肌最小肌腱的两个滑动延伸。在中期和晚期的腕骨远端水平，肌腱鞘丢失了，每个指伸肌腱滑动进一步分开，以提供一个中外侧线性簇的细束。大量的肌腱组件连接并结合在一起，以在掌指关节水平提供单个紧密的肌腱。伸肌肌腱长肌腱在穿过radi骨伸肌短肌腱时通常会失去膜状隔膜。
结论：根据机械需求，出生后第四和第五根鞘管的肌腱滑脱最有可能减少。
BACKGROUND: To understand considerable variations in number of adult extensor ten-dons at the dorsal side of the wrist and hand.
METHODS: We examined histological sections from 30 human fetuses of gestational age 7-39 weeks and crown-rump length 22-323 mm.
RESULTS: At the carpal level, earlier or smaller fetuses showed a simpler configuration with fewer tendon slips, whereas later or larger fetuses had a greater number of tendon slips with considerable variations in number and topographical relationships. Tendon slips of the early extensor digitorum to the middle and ring fingers were always 1 or 2, but were seven or more at late term. A tendon of the extensor digitorum to the little fin-ger could not be distinguished from other tendons at the carpal bone level. At the meta-carpal bone level, however, it extended from the ring finger tendon toward two slips of the extensor digiti minimi tendon. At the distal carpal level at midterm and late term, in which the tendon sheath was lost, each of the extensor digitorum tendon slips further divided to provide a mediolateral linear cluster of thin bundles. This large number of tendon components joined and united together to provide a single tight tendon at the level of the metacarpophalangeal joints. The extensor pollicis longs tendon usually lost a membranous septation when it crossed the extensor carpi radialis brevis tendon.
CONCLUSIONS: Tendon slips in the fourth and fifth canals of the sheath were most likely to reduce in number after birth depending on the mechanical demand.
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