黄韧带位于硬膜外腔后方,从枕骨大孔延伸至骶裂孔,由左、右两条黄韧带组成,在后正中连接呈锐角,而腹侧是开放的.自颅骨至骶骨,甚至在同一椎间隙,黄韧带并非均匀一致,韧带的厚度、与硬脊膜的距离以及皮肤与硬脊膜的距离均随所处椎管的节段而改变.腰段椎管呈三角形而且最宽,胸段椎管呈圆形而且最窄.两条黄韧带在中线处的连接情况是可变的,甚至同一患者在不同椎体水平亦可能同时出现两侧黄韧带融合或不融合这两种情况.黄韧带的这种解剖特点对硬膜外腔穿刺所采用的“阻力消失技术”影响重大.分析不同脊柱节段黄韧带中线缺口的情况,总体来讲,黄韧带中线缺口的发生率颈段最高,胸段次之,而腰段最低.然而,在正中入路进行硬膜外腔穿刺时,穿刺者不应对所有患者均依赖穿透黄韧带的感觉判断穿刺针位置.%The ligamentum flavum lies in the posterior to the epidural space,which also extends from the foramen magnum to the sacral hiatus.Ligamentum flavum is comprised of two ligamenta flava-the right and the left-which join in the middle and form an acute angle with a ventral opening.The ligamentum flavum is not uniform from skull to sacrum,nor even within an intervertebral space.Ligament thickness,distance to the dura,and skin-to-dura distance vary with the area of the vertebral canal.The vertebral canal is triangular and largest in area at the lumbar levels,and it is circular and smallest in area at the thoracic levels.The two ligamenta flava are variably fused in the midline,and this fusion or lack of fusion of the ligamenta flava even occurs at different vertebral levels in individual patient.Such anatomy feature is quite meaningful to the "loss of resistance technique" for epidural injection.Analysis and summaries of such different situations of ligamentum flavum gaps in different vertebral levels:in general,cervical ligamentum flavum has the highest incidence in midline gap,lower in thoracic,and lowest in lumbar area.However,when performing epidural puncture at the median approach,the performer should not rely on the sensation of penetrating the yellow ligament to determine the location of the needle for all patients.
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