title: Anatomic study of the extensor carpi radialis brevis in its relation with the motor branch of the radial nerve.
abstract: BACKGROUND
  The cause of the tunnel syndrome is the entrapment of the posterior interosseous nerve, and can occur due to different anatomic structures, the arcade of Frohse being the main one of them.
  
  
  OBJECTIVE
  To describe the anatomic relation between the extensor carpi radialis brevis (ECRB) muscle and the motor branch of the radial nerve at its entrance under the arcade of Frohse.
  
  
  METHODS
  An anatomic dissection of 21 elbows of fresh human cadavers was conducted, describing the deep aponeurosis and the superomedial tendinous arch of ECRB and its relation with the motor branch of the radial nerve.
  
  
  RESULTS
  In 100% of the specimens, there was evidence of an aponeurosis in the undersurface of ECRB. A tendinous arch at the superomedial margin of ECRB was found in 20 cases (95.2%). In 71.5%, this arch surpassed proximally the arcade of Frohse on an average of 4.5mm (2-10mm); it passes in direct contact with the motor branch of the radial nerve.
  
  
  CONCLUSIONS
  The extensor carpi radialis brevis muscle courses in a close relation to the motor branch of the radial nerve at its entrance under the arcade of Frohse, and it demonstrates an aponeurosis at its undersurface and a tendinous arch at its medial edge that could play an important role in the development of the radial tunnel syndrome.
  
  
  METHODS
  Level IV. Anatomic research study.
authors.affiliation: Unidad de Ortopedia, Facultad de Medicina, Universidad Nacional de Colombia, Ciudad Universitaria, Carrera 30 Calle 45, Bogotá, Colombia. Electronic address: enriquevergaramd@gmail.com.
authors.forename: E
authors.initials: E
authors.lastname: Vergara-Amador
authors.affiliation: Unidad de Ortopedia, Facultad de Medicina, Universidad Nacional de Colombia, Ciudad Universitaria, Carrera 30 Calle 45, Bogotá, Colombia. Electronic address: alejandro_rga@hotmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Ramírez
mesh_terms: D002102:Cadaver; D004210:Dissection; D004550:Elbow / Q000033:anatomy & histology*; D004551:Elbow Joint / Q000294:innervation; D005260:Female; D005542:Forearm / Q000033:anatomy & histology; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000294:innervation; D009408:Nerve Compression Syndromes / Q000209:etiology / Q000473:pathology; D010525:Peripheral Nerves; D011826:Radial Nerve / Q000033:anatomy & histology*; D020425:Radial Neuropathy / Q000209:etiology; D013710:Tendons / Q000033:anatomy & histology*
keywords: Anatomy; Radial nerve; Tennis elbow