title: Ultrasound anatomy of the brachial plexus nerves in the neurovascular bundle at the axilla in patients undergoing upper-extremity block anesthesia.
abstract: OBJECTIVE
  Familiarity with the localization of the nerves in the neurovascular bundle that constitutes the axillary segment of the brachial plexus (BP) is important when applying ultrasound (US)-guided block anesthesia. Therefore in this study we aimed to delineate the anatomy of the median, radial, and ulnar nerves of the BP at the axilla with US and electrical stimulation.
  
  
  METHODS
  The study included 60 patients who were scheduled to undergo upper-arm surgery with axillary block anesthesia. Prior to anesthesia, ulnar, radial, and median nerves were localized with US using a 12-h quadrant identification system that placed the axillary artery (AA) in the middle. The nerves were then functionally tested using a neurostimulator.
  
  
  RESULTS
  The radial nerve was mainly located in the 4-6 o'clock arc (posterior and posteromedial to AA) in 50 (83 %) of patients. Ulnar nerve was mainly at the 12-3 o'clock arc (anteromedial to AA) in 51 (85 %) of patients. Ulnar nerve showed a second peak at 9-10 o'clock quadrant (anterolateral to AA) in 11 % (7) of patients. Median nerve location was most common in the 12 and 9 o'clock arc (anterior and anterolateral to AA) in 53 (88 %) of the patients.
  
  
  CONCLUSIONS
  Ultrasound is a useful tool for depicting BP anatomy in the axillary fossa prior to block anesthesia. Median, ulnar, and radial nerves form a highly consistent triangular pattern around the axillary artery that is easily recognizable with US.
authors: Radiology Department, Ankara University School of Medicine, Ankara, Turkey. evrenustuner@hotmail.com
authors: Evren
authors: E
authors: Ustuner
authors: Ayse
authors: A
authors: Yılmaz
authors: Enver
authors: E
authors: Özgencil
authors: Feyhan
authors: F
authors: Okten
authors: Sanem Cakar
authors: SC
authors: Turhan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001365:Axilla; D001917:Brachial Plexus / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D008875:Middle Aged; D009407:Nerve Block; D011826:Radial Nerve / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D014459:Ulnar Nerve / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D014463:Ultrasonography; D034941:Upper Extremity / Q000601:surgery; D055815:Young Adult
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