Ileum

The ileum is the final part of the small intestine, following the duodenum and jejunum.

The ileum is not to be confused with the ilium - the associated plural/adjectival forms are ilea/ileal and ilia/ilial respectively.

The ileum is 2-4 m in length and is separated from the caecum by the ileocaecal valve (ICV). While there is no discrete line demarcating the jejunum from the ileum, there are a few differences between the two:

  • ileal mesentery contains more fat than jejunal mesentery
  • ileum tends to be smaller calibre than jejunum
  • ileum tends to be lighter in colour than the jejunum
  • ileum contains abundant Peyer patches
    • Peyer patches contained in the ileum are unencapsulated lymphoid nodules that contain large amounts of lymphocytes and other cells of the immune system
  • drain to superior mesenteric lymph nodes
  • via superior mesenteric plexus
    • sympathetic supply from lateral horn cells of the T9-T10 spinal cord
    • parasympathetic supply from vagus nerves
Anatomy: Abdominopelvic
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Article information

rID: 5715
Section: Anatomy
Tag: cases, cases
Synonyms or Alternate Spellings:
  • Ileal anatomy
  • Ilea

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