title: The anatomy of the extrathoracic intercostobrachial nerve.
abstract: BACKGROUND
  In the past decade surgeons have become increasingly aware of the morbidity caused by the division of the intercostobrachial nerve (ICBN) during axillary dissection. To prevent this problem and also to explain its variable occurrence, a detailed knowledge of the anatomy of the nerve is required.
  
  
  METHODS
  Twenty-eight axillary dissections were performed demonstrating the anatomy of the ICBN.
  
  
  RESULTS
  In all dissections the nerve originated from the second intercostal space, with contributions from the first and third intercostal nerve each on one occasion. The posterior axillary branch was constant but may branch early, simulating a second nerve. The ICBN had a variable relationship to the lateral thoracic vein: anterior, posterior or wrapping around it. In 36% there was a connection to the medial cord of the brachial plexus in the axilla. In the upper arm the nerve lies in the subcutaneous fat; in the majority it supplied at least the proximal half of the arm, and in one-third it reached the level of the elbow joint. In 18% there was a connection to the medial cutaneous nerve of the arm.
  
  
  CONCLUSIONS
  The ICBN and its main branch (the posterior axillary nerve) were constant in all dissections. But its origin, size, connection to the brachial plexus and medial cutaneous nerve of the arm were variable, as was its ultimate destination in the arm.
authors.affiliation: Department of Surgery, Mater Misericordiae Hospital, South Brisbane, Australia.
authors.forename: M G
authors.initials: MG
authors.lastname: O'Rourke
authors.forename: T S
authors.initials: TS
authors.lastname: Tang
authors.forename: S I
authors.initials: SI
authors.lastname: Allison
authors.forename: W
authors.initials: W
authors.lastname: Wood
mesh_terms: D001132:Arm / Q000294:innervation; D001365:Axilla; D001917:Brachial Plexus / Q000033:anatomy & histology* / Q000601:surgery; D005260:Female; D006801:Humans; D007367:Intercostal Nerves / Q000033:anatomy & histology* / Q000601:surgery; D008197:Lymph Node Excision; D008297:Male; D013900:Thoracic Nerves / Q000033:anatomy & histology; D013909:Thorax / Q000098:blood supply