title: Dynamic analysis of the ulnar nerve in the cubital tunnel using ultrasonography.
abstract: BACKGROUND
  We investigated the dynamics of the ulnar nerve during elbow flexion and the relationships between these dynamics and the morphology of the ulnar nerve groove in healthy individuals.
  
  
  METHODS
  Twenty healthy volunteers (40 elbows) underwent ultrasonographic examination of the ulnar nerve at the elbow. We measured the breadth and depth of the ulnar nerve groove at 90° of elbow flexion and calculated the depth-to-breadth ratio. We recorded the distance from the trochlea of the humerus to the nerve and the short-axis diameter of the nerve at 30°, 60°, 90°, and 120° of elbow flexion. We calculated the medial shift and flattening of the ulnar nerve at each angle relative to 30° of flexion, compared the values among the different angles, and compared the depth-to-breadth ratio with the location, medial shift, and flattening ratio of the ulnar nerve.
  
  
  RESULTS
  The medial shift was significantly greater at 120° than at other angles (P < .001). Flattening increased with increasing elbow flexion and was significantly different at 60°, 90°, and 120° (all P < .001). The flattening ratios were significantly correlated with the depth-to-breadth ratio at 120° (r = -0.43, P = .005).
  
  
  CONCLUSIONS
  The ulnar nerve moves medially and is flattened with the elbow flexed between 90° and 120°. When the ulnar nerve groove is shallow, high degrees of elbow flexion result in flattening of the ulnar nerve in the groove.
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Nakano
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Murata
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan. Electronic address: omokawa@naramed-u.ac.jp.
authors.forename: Shohei
authors.initials: S
authors.lastname: Omokawa
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Nakanishi
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.
authors.forename: Takamasa
authors.initials: T
authors.lastname: Shimizu
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kira
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.
authors.forename: Tadanobu
authors.initials: T
authors.lastname: Onishi
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004551:Elbow Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D014459:Ulnar Nerve / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D014463:Ultrasonography; D055815:Young Adult
keywords: Ultrasonography; dynamics; elbow; groove; morphology; ulnar nerve