Rectum

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Rectum Anal canal
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Objectives

• Discuss the anatomical structure of the rectum.
• Describe the anatomical structure of the anal
  canal.
• Give the blood supply of rectum and anal canal.
• Define external and internal hemorrhoids.

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Rectum
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Location and peritoneal relations of the rectum
S3
12 cm
1 inch infront of coccyx
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Shape (flexures) of the rectum

• - Anteroposterior curve
• - 3 flexures
• Upper concave to left
• lower concave to left
• Middle concave to right

Rectal ampulla
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Rectum
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Relations of rectum
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Anterior relations of the rectum
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Posterior relations of the rectum
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Per rectal (PR) examination

• Knee-chest position
• Index finger introduced into lower rectum through
  anal orifice
• Structures palpated
• Anterior
• Posterior
• On each side

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Blood supply of rectum
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Arterial supply of the rectum and anal canal
median sacral artery
superior rectal artery (inferior mesenteric)
middle rectal artery (internal iliac)
inferior rectal artery (internal pudendal)
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Arteries of the rectum and anal canal

• Superior rectal
• Middle rectal
• Inferior rectal
• Median sacral

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Veins of the rectum
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Hemorrhoids

• Internal hemorrhoids
• Tributary of sup rectal
• Above white line
• Generally painless
• External hemorrhoids
• Tributary of inf rectal
• Below white line
• Generally painful

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• Lymph drainage of rectum
• Upper half drains to para rectal L.Ns which drain
  to inferior mesenteric L.Ns.
• Lower half drains to internal iliac lymph nodes.
•  

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Lymphatic drainage of the rectum
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Anal canal

• Beginning It begins one inch below and anterior
  to the tip of the coccyx at the recto-anal
  junction.
• Course It runs down and backwards.
• Termination It ends at the anus.
• Relations
• Laterally Ischioanal fossae.
• Posteriorly Anococcygeal raphe between it and
  tip of coccyx.
• Anteriorly Perineal body between it and bulb of
  penis in males. Perineal body
  between it and vagina in females.

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anal sinus
anal valve
Pectinate line (dentate line)
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Blood supply, nerve supply and lymph drainage of
anal canal
  Upper part Lower part
Blood supply     -It is supplied by superior rectal artery. - It is drained by superior rectal vein (portal circulation).   -It is supplied by 1- Middle rectal artery of internal iliac artery. Inferior rectal artery of internal pudendal artery. -The corresponding veins drain into internal iliac vein (systemic circulation.)  
Nerve supply Above pectinate line by autonomic nerve fibers. Below pectinate line by inferior rectal nerve (Sensitive to pain touch).
Lymphatic drainage Above pectinate line into internal iliac LNs. Below the pectinate line into superficial inguinal LNs.
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Anal sphincters

• Internal anal sphincter
• -It is the thickened inner involuntary circular
  muscle layer of the anal canal.
• -Surrounds the upper 3/4th of the anal canal,
  extending from ano-rectal junction till the white
  line (Hiltons line).
• Nerve supply autonomic
• External anal sphincter
• -Striated voluntary muscle fibers.
• -Surrounds the whole length of the anal canal
  outside the internal anal sphincter.
• -Parts I) Subcutaneous Part
• -Surrounds the anus just under the perianal
  skin.
• -Attached to perineal body anococcygeal raphe.
• II) Superficial Part
• -Surrounds the lower part of the internal
  sphincter above the subcutaneous part.
• III) Deep Part

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Relations of the Anal Canal

• The anal canal is related
• posteriorly to the fibrous tissue between it and
  the coccyx (anococcygeal body),
• laterally to the ischiorectal fossae containing
  fat,
• anteriorly to the perineal body separating it
  from the bulb
• of the urethra in the male or the lower vagina in
  the female.

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anal sinus
anal valve
Pectinate line (dentate line)
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Sphincters of the anal canal
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The external sphincter
(voluntary)
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Vessels and nerves of the anal canal
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