阑尾(appendix)
全名名蚓状阑尾（vermiform appendix）
解剖学上附於大肠的盲肠（Cecum）的一条退化性中空管。人类的阑尾长约3～4寸（8～10公分），宽不及0.5寸（1.3公分），没有消化功能。阑尾的肌质壁可将管壁分泌的黏液或误入管腔的消化物挤回盲肠，因此如果阑尾开口受堵或排出功能受阻，皆可能导致阑尾炎。当阑尾无法排空时，消化液和黏液会逐渐累积而使阑尾水肿、胀大和变形，接着血液回流会受阻而产生坏死，同时原先寄生在此处的细菌会趁机繁殖而使炎症反应加剧，如果这些现象继续恶化下去，阑尾可能会胀破而将其内容物洒入腹腔，进而引发腹膜炎。阑尾炎最初的症状为局限於上腹部或肚脐周围的模糊性疼痛，接着变成局限於右下腹部的持续性疼痛。体温上升亦很常见，但在早期很少太高；白血球（leukocyte）通常会上升至12,000～20,000。阑尾炎的疼痛部位会随阑尾的解剖位置而异，常会与其他腹部急症所引起的腹痛混淆，因此需仔细检查方能确定是否真的罹患了急性阑尾炎。阑尾炎的基本治疗法为开刀切除（俗称阑尾切除术〔appendectomy〕）。
English version：
appendix
Vestigial hollow tube attached to the cecum of the large intestine. The human appendix, usually 3-4 in. (8-10 cm) long and less than 0.5 in. (1.3 cm) wide, has no digestive function. Its muscular walls expel their own mucous secretions or any intestinal contents that enter it. Blockage of the opening may prevent expulsion and cause appendicitis: fluids collect, bacteria propagate, and the appendix becomes distended and inflamed; tissue in the appendix begins to die, and the organ may burst, causing peritonitis. Its symptoms may begin with moderate pain in the upper abdomen, about the navel, or all over the abdomen. Nausea and vomiting may then develop. The pain may shift to the right lower abdomen, where the appendix is (unless it is in an abnormal location). Fever is usually present but is seldom high in the early phases. The leukocyte count is high (12,000-20,000). Differentiating acute appendicitis from other causes of abdominal pain requires careful examination. Treatment is removal of the appendix (appendectomy).