Anatomic Variations of the Spinal Origins of the Main Terminal Branches of the Brachial Plexus

Koo, Jung Hoi; Lee, Kyu Seok

Abstract

Variations of spinal nerue compositions, which giue rise to the variable motor and sensory component, occured at the terminal branches of brachial plexus. This study performed to investigate the spinal nerve compositions of the main terminal branches of the brachial plexus in 32 sides of Korean adults. The main terminal branches contained the musculocutaneous, median, ulnar, radial and axillary nerves. The obtained results were as follows. The spinal nerve compositions of musculocutaneous nerve appeared as two types. The most frequent type was composed of C5, C6 and C7 at 75.0%. The mean diameter of C5 and C6 was 1.68+/-0.21 mm and 1.66+/-0.40 mm, respectively. The median nerve appeared as two types. The most frequent type was composed of C6, C7, C8, T1 components at 87.5%. The mean diameter of C7 was the thickest at 2.64+/-0.48 mm and C5 was most thin at 0.28+/-0.04 mm. The ulnar nerve appeared as four types. The most frequent type was comprised with C7, C8 and T1 at 75.0%. In the mean diameter, C8 was the thickest with 2.64+/-0.57mm and T1 was most thin with 0.06+/-0.56 mm. The radial nerve appeared as four types. The most frequent type was comprised from C5 to T1 at 43.7%. In the mean diameter, C7 was the thickest at 2.70+/-0.52 mm. The axillary nerve appeared as two types. The frequentest type was comprised with C5, C6 and C7 at 56.2%. In the mean diameter, C6 was the thickest at 1.73+/-0.56 mm. From the obtained results, spinal nerve compositions of the main terminal branches of the brachial plexus were more variable than the description of the anatomic textbook.