食(shi)(shi)(shi)管(guan)(guan)(guan)(guan)狹(xia)窄是因(yin)食(shi)(shi)(shi)管(guan)(guan)(guan)(guan)胚胎(tai)發育過程中(zhong),氣管(guan)(guan)(guan)(guan)、食(shi)(shi)(shi)管(guan)(guan)(guan)(guan)隔膜基(ji)底部或食(shi)(shi)(shi)管(guan)(guan)(guan)(guan)側嵴中(zhong)胚葉成(cheng)分過度增生(sheng)的結果,多發生(sheng)在氣管(guan)(guan)(guan)(guan)分叉以(yi)下(xia)位置。
后天性(xing)狹窄常見原(yuan)因:
1、食(shi)管粘膜上皮因炎癥破壞或化學藥(yao)品腐蝕,修復后形成瘢痕(hen)性(xing)狹窄;
2、食管(guan)(guan)腫瘤如食管(guan)(guan)癌不同程度阻塞食管(guan)(guan)管(guan)(guan)腔;
3、食管周圍(wei)組(zu)織病(bing)變從(cong)外部壓迫食管所致,如(ru)肺及縱隔腫瘤,動(dong)脈瘤,甲狀(zhuang)腺腫等(deng)。
食(shi)管(guan)的管(guan)徑并(bing)非上下均勻(yun)一致,由于(yu)食(shi)管(guan)本身的結(jie)構特點以及鄰近器官(guan)的影響,食(shi)管(guan)呈現3個狹(xia)窄(zhai)部(bu)(bu):第(di)(di)(di)一狹(xia)窄(zhai)部(bu)(bu)位于(yu)咽與食(shi)管(guan)交接處,距(ju)中(zhong)切(qie)牙15cm;第(di)(di)(di)二狹(xia)窄(zhai)部(bu)(bu)位于(yu)氣(qi)管(guan)杈水平,左主支氣(qi)管(guan)跨越其(qi)前方,相(xiang)當(dang)(dang)于(yu)胸(xiong)骨角或第(di)(di)(di)4與第(di)(di)(di)5胸(xiong)椎椎間盤水平,距(ju)中(zhong)切(qie)牙25cm;第(di)(di)(di)三狹(xia)窄(zhai)部(bu)(bu)為(wei)食(shi)管(guan)通(tong)過膈食(shi)管(guan)裂孔處,相(xiang)當(dang)(dang)于(yu)第(di)(di)(di)10胸(xiong)椎水平,距(ju)中(zhong)切(qie)牙37~40cm。
食(shi)管(guan)(guan)(guan)的(de)兩端,即第(di)一和(he)第(di)三狹(xia)窄部經(jing)常處于閉(bi)合狀態,前者阻(zu)止在吸(xi)氣時空氣從咽(yan)進入食(shi)管(guan)(guan)(guan),后者可(ke)防止胃內容物(wu)逆流入食(shi)管(guan)(guan)(guan)。第(di)二狹(xia)窄部由鄰近(jin)的(de)主動脈弓和(he)左主支氣管(guan)(guan)(guan)擠壓所致,此狹(xia)窄部并不影響食(shi)物(wu)的(de)通過,也無生理(li)功能上的(de)意(yi)義,但(dan)第(di)二狹(xia)窄部常是(shi)異(yi)物(wu)嵌頓滯(zhi)留及食(shi)管(guan)(guan)(guan)癌的(de)好發部位(wei)。
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