下消化道解剖學


I.     Embryology

A.    Midgut –- 十二指腸到橫結腸上三分之二上腸繫脈動脈支配

1.    上段 – Vitelline duct(Meckel’s diverticulum) – 下段

2.    6th Wk.生理性 疝氣 (肝臟快速發育)– 270o逆時針扭轉

3.    3rd Mn返回腹腔(肝臟穩定發育)—Jejunum右側,Cecum左側

umbilical hernia, omphalocele, malrotation  

B.    Hindgut –- 橫結腸後三分之一到肛門下腸繫脈動脈支配

1.    7th Wk.泌尿直腸膈 泄殖腔膜 發育  泌殖窩與肛管分隔

2.    9th Wk.肛門窩凹陷與肛管相通(洩殖腔膜後段破裂)-- imperforated anus

II. CIRCULATION

A.    Arterial System

1.    Colon

a.    Superior Mesenteric Artery (SMA)

1.    Ileocolic – Cecum ,Appendix and Ascending colon

2.    Right colic– Right colon

3.    Middle colic–Transverse colon(5%pancreatoduodenal a.)

b.    Inferior Mesenteric Artery (IMA)

1.    Left colic— Left colon

2.    Sigmoid— Sigmoid colon

3.    Superior Rectal (hemorrhoidal)—Upper rectum

splenic flexure: 37% from SMA, 86% from IMA

marginal artery (of Drummond) and the critical point of Sudeck

2.    Anorectum

a.    Internal Iliac Artery

1.    Middle Rectal (uterine a.)—1/4 lateral ligament

2.    Inferior Rectal —distal to dentate line

b.    Middle Sacral Artery

B.    Venous System

1.    Colon —Portal system

a.    Superior Mesenteric vein (SMV)

b.    Inferior Mesenteric vein (IMV)

2.    Anorectum —Inferior Vena Cava system (IVC)

a.    Middle Rectal (Hemorrhoidal) vein

b.    Inferior Rectal (Hemorrhoidal) vein

portosystemic shunt—upper & middle rectal vein