Rectum & Anal canal

Question 1

course of Rectum

Answer 1

• begins at S3 level
• Ends 1 inch below tip of coccyx, where it bends backwards (as perineal flexure) to form anal canal

Question 2

flexures of Rectum

Answer 2

1. follows sacro-coccygeal flexure
2. Perineal flexure –> to become anal canal
3. upper & lower concavities to the left
4. middle concavity to the right

Question 3

length of rectum

Answer 3

5 inches

Question 4

Peritoneal covering of Rectum

Answer 4

• Upper 1/3 completely covered
• Middle 1/3: anterior covered only
• Lower 1/3: Devoid of Peritoneum –> peritoneoum reflected foreward

Question 5

Anterior relation of Rectum

Answer 5

🚹:
upper 2/3:
* rectovesical pouch containing coils of sigmoid colon & Ilium –> seperating rectum from Bladder
Lower 1/3:
* Seminal vesicles
* Vas deferns (terminal part)
* (posterior surface of) prostate

🚺:
Upper 2/3:
* Douglas pouch containing coils of sigmoid colon & Ilium –> seperating rectum from uterus & upper 1/3 of vagina

Lower 1/3:
* Posterior wall of vagina (middle 1/3)

Question 6

relations of Rectum bed/ Posterior wall of Rectum

Answer 6

• Coccygeus
• Piriformis
• Levator Ani
• ano-coccygeal ligament
• Sacral plexus
• pelvic sympathetic chain
• ganglion impar (termination of Symp. chain)
• Sup. Rectal Artery
• Median Sacral A
• Two lateral sacral A
• Lower 3 sacral vertebra bones
• coccyx bone

Question 7

Lateral relations of Rectum

Answer 7

Upper 1/3:
* Pararectal fossa (containing coils of sigmoid colon & ileum)

Lower 2/3:
* Pelvic floor muscles (Levator Ani & Coccygeus)
* Inferior hypogastric Plexus

Question 8

Arteries supplying rectum & their course

Answer 8

Superior Rectal A:
* continuation of inferior mesenteric A
* Divides into right and left branches behind rectum
* anastomoses with Ascending branches of inferior rectal A

Middle rectal A:
* originates from Anterior division of IIA
* both right & left branches run medialy & supply lower & middle rectum
* Anastomose weakly with Sup & Inf rectal A

Inferior Rectal A:
* originates from Internal Pudendal A
* supply lower rectum & lower 1/2 anal canal
* Anastomoses with superior rectal A

Question 9

Sympathetic Innervation of Rectum

Answer 9

Inf. mesenteric plexus –> L1 & L2

Question 10

parasympathetic Innervation of Rectum

Answer 10

Pelvic splanchnic Nerve (S2,S3,S4)

Question 11

Porto-systemic anastomosis of rectum

Answer 11

Superior rectal vein (drains in splenic v —> portal V) communicates with Inferior rectal vein (Systemic)

Question 12

Lymph drainage of Rectum

Answer 12

Upper part:
* Pararectal LN
* Inferior mesenteric LN

Lower part:
* Internal Iliac LN