II. Physiology

  1. Rectum is lower 10 to 15 cm of Large Intestine

III. Anatomy: Images

  1. giRectumGrayBB1078.gif Lewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
  2. giAnusGrayBB1080.gif Lewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)

IV. Anatomy

  1. Perianal skin
    1. Typical skin that bears hair and glands
  2. Anal Verge
    1. Analogous to vermillion border of lips
  3. Squamous Epithelium
    1. Exquisitely sensitive
    2. Shiny white mucosa
    3. External Hemorrhoids start here
  4. Dentate Line (Pectinate Line)
    1. Divides squamous epithelium from columnar epithelium
    2. Delineates end of pain sensory fibers
    3. Contains Anal glands (4 to 8)
      1. Drain into Crypts of Morgagni
      2. Responsible for most rectal abscesses and fistulae
  5. Mucosal Glandular Epithelium
    1. No Pain Sensation (stretch nerve fibers present)
    2. Deeper pink or red mucosa
    3. Internal Hemorrhoids start here
  6. Valves of Houston (superior, middle, and inferior)
    1. Prominent mucosal folds within Rectum

VI. Examination

  1. Patient position and preparation
    1. Left lateral decubitus position
    2. Assistant or patient spreads buttocks
  2. Findings on Inspection
    1. Anal Fissures
    2. Anorectal Fistula
    3. Perianal Dermatitis
    4. Anal mass
    5. External Hemorrhoid
    6. Anogenital Wart
    7. Perirectal Abscess
    8. Fecal Impaction
  3. Rectal Examination
    1. Digital Rectal Exam
      1. Rectal Mass
      2. Fecal Occult Blood
    2. Anoscopy
      1. Internal Hemorrhoid

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