Anatomical and clinical study of median nerve entrapment at the elbow

Objective To provide anatomic and clinical basis for diagnosis and treatment of median nerve entrapment at the elbow.Methods Microanatomical dissection of the median nerve was done in 10 cadaver upper limb specimens to observe the anatomical factors that cause compression of the median nerve at the elbow and shape of the median nerve.Case analysis was conducted in 14 patients with median nerve entrapment at the elbow who were treated in our department.Results Anatomic studies in the 10 dissected specimens showed three types of relationship between the bicepital aponeurosis and median nerve:complete-covering (2 specimens,20％),partial-covering (1 specimen,10％) and non-covering (7 specimens,70％).Thickened fascia in the superficial layer of pronator teres ulnar head was seen in 9 specimem (90％).Intramuscular tendinous bundles in the anconeus were observed in 2 specimem (20％).The reverse fascia that traversed the median nerve was seen in 6 specimens (60％).The structures of the origins of two heads of the flexor digitorum superficialis (FDS) had three types:intramuscular tendinous bundle (1 specimen,10％),fibrous arch (1 specimen,10％),and conjoined tendinous arch (8 specimens,80％).Of the 14 patients who had median nerve entrapment at the elbow,5 were diagnosed as pronator teres syndrome while 9 were diagnosed as anterior interosseous nerve(AIN) compression.The compression points in the pronator syndrome cases were ulnar side of the thickened and taut bicepital aponeurosis (2 cases),deep tendinous arch of pronator teres (2 cases),and between two heads of pronator teres (1 case).The compression points in the AIN compression cases were deep tendinous arch of pronator teres (2 cases),ulnar head of pronator teres (1 case),between two heads of pronator teres (1 case),and thickened and taut FDS origin (5 cases).Six patients were follow-up.The average follow-up time was 2 years and 4 months.Good to excellent recovery of motor function was achieved in these patients.Condusion The shape of the median nerve,its surroanding tendinous structures and thickened and taut fascia are the anatomic basis of median nerve entrapment at the elbow. Key words: Median nerve;  Entrapment;  Elbow;  Applied anatomy;  Case report