Dr Henry Knipe and Dr Jeremy Jones et al.

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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