title: Correlation of ultrasound appearance, gross anatomy, and histology of the femoral nerve at the femoral triangle.
abstract: OBJECTIVE
  Correlation between ultrasound appearance, gross anatomic characteristics, and histologic structure of the femoral nerve (FN) is lacking. Utilizing cadavers, we sought to characterize the anatomy of the FN, and provide a quantitative measure of its branching. We hypothesize that at the femoral crease, the FN exists as a group of nerve branches, rather than a single nerve structure, and secondarily, that this transition into many branches is apparent on ultrasonography.
  
  
  METHODS
  Nineteen preserved cadavers were investigated. Ultrasonography was sufficient to evaluate the femoral nerve in nine specimens; gross dissection was utilized in all 19. Anatomic characteristics were recorded, including distances from the inguinal ligament to femoral crease, first nerve branch, and complete arborization of the nerve. The nerves from nine specimens were excised for histologic analysis.
  
  
  RESULTS
  On ultrasound, the nerve became more flattened, widened, and less discrete as it coursed distally. Branching of the nerve was apparent in 12 of 18 images, with mean distance from inguinal ligament of 3.9 (1.0) cm. However, upon dissection, major branching of the femoral nerve occurred at 3.1 (1.0) cm distal to the inguinal ligament, well proximal to the femoral crease. Histologic analysis was consistent with findings at dissection.
  
  
  CONCLUSIONS
  The femoral nerve arborizes into multiple branches between the inguinal ligament and the femoral crease. Initial branching is often high in the femoral triangle. As hypothesized, the FN exists as a closely associated group of nerve branches at the level of the femoral crease; however, the termination of the nerve into multiple branches is not consistently apparent on ultrasonography.
authors.affiliation: Department of Anesthesiology, University of Pittsburgh School of Medicine, 3471 Fifth Avenue, Suite 910, Pittsburgh, PA, 15213, USA. lonchenatk@upmc.edu.
authors.forename: Tiffany K
authors.initials: TK
authors.lastname: Lonchena
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Kathryn
authors.initials: K
authors.lastname: McFadden
authors.affiliation: Department of Anesthesiology, University of Pittsburgh School of Medicine, 2000 Mary Street, Pittsburgh, PA, 15203, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Orebaugh
mesh_terms: D005260:Female; D005267:Femoral Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D014463:Ultrasonography
keywords: Anatomy; Femoral; Nerve; Nerve block; Ultrasound
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