Patterns of connections between the musculocutaneous and median nerves in the axilla and arm

Abstract

Variations in connections between the musculocutaneous and median nerves in the arm are not as uncommon as was once thought. This opinion led us to perform a study in 138 cadavers (66 male, 72 female). These variations were seen in 64 cadavers (46.4%), 9 bilaterally and 55 unilaterally (26 right and 29 left); in total, therefore, variations were observed in 73 out of 276 arms (26.4%), 42 male and 31 female. No statistically significant differences by gender and side were observed. We classify the variations in three main patterns: Pattern 1, fusion of both nerves (14 arms, 19.2%); Pattern 2, presence of one supplementary branch between both nerves (53 arms, 72.6%); and Pattern 3, two branches (5 arms, 6.8%). Pattern 2 was further subdivided into a sub-group 2a when a single root from the musculocutaneous nerve contributed to the connection (51 arms, 69.9%), and 2b when there were two roots from the musculocutaneous nerve (2 arms, 2.7%). A combination of Patterns 1 and 2a was observed in one case (1.4%). Further variations are described, published classification systems are reviewed and a meta-analysis of previous results is presented. An overall incidence of 33% of variant arms was observed. Of these variant arms, Pattern 1 represented 13.1%, Pattern 2 represented 75.4%, and Pattern 3, 8.5%, similar to our figures.

Communication between musculocutaneous and median nerves: a case report

“…4,10 In the present case only one communication is seen, which is a rare case finding. Le Minor 2 has classified the variations of MCN and MN into five types.…”

“…In a recent study by Choi et al, communications between MCN and MN have been broadly classified into three types. 4 In type I: the MCN and MN were fused; in type II: there was one connecting branch between the MCN and MN and in type III: two connecting branches were present between MCN and MN. So, the present case coincides with type II category of Choi D classification.…”

Connection between Radial and Ulnar Nerves at Humeral Level And Its Clinical Significance: A Cadaveric Case Report

“…Pattern of motor branching of this nerve in human fetuses were also studied by Kervancioglu et al (2011). Communication between musculocutaneous and median nerves in arm has been observed in 46.4% studied cases by Choi et al (2002). Frequency of this anomaly has been reported 63% by Loukas & Aqueelah (2005).…”

A study of anatomical variations of median nerve in human cadavers

“…4 Aktan et al (2001) in their study of 48 limbs, have reported median nerve communications with musculocutaneous nerve in 5 (5%) limbs. 24 Choi et al (2002) in their study of 276 upper limbs found median nerve communications with musculocutaneous nerve in 73 (26.4%) limbs. In 9 cadavers these were bilateral.…”

“…In 9 cadavers these were bilateral. 25 Beheiry (2004) in his study of 60 cadaver arms noticed communications between median nerve and musculocutaneous nerve in 3 (5%) limbs. 17 Guttenberg and Ingolotti (2009) in their study of 56 upper limbs have reported median nerve communications with musculocutaneous nerve in 30 (53.6%) limbs.…”