Variations in innervation of muscles in anterior compartment of arm - a cadaveric study

Study was undertaken to observe the variation in the innervation of muscles in the front of arm. The results were compiled. Embryological basis and clinical applications of encountered variations were tried to explain with the help of available literature.

Thirty upper limbs from fifteen cadavers were dissected to observe the contents of front of arm. Musculocutaneous nerve, median nerve and innervation of the muscles of front of arm were observed.

Variations were observed in 13% of cases. Commonly seen variation was the absence of musculocutaneous nerve and innervation of muscles of front of arm by branches of median nerve. This variation was seen bilaterally in 3.3% of cases and unilaterally in 6.6% cases. Bilateral presence of this variation in one out of fifteen cadavers is rare finding. Variation is more common on right side as compared to the left side.

Bilateral absence of musculocutaneous nerve and innervation of muscles of front of arm from the branches of median nerve is a rare variation. Knowledge of such anatomical variations is of interest to the anatomist and clinician alike. Variations assume significance during surgical exploration of the axilla and can even fail nerve block of infraclavicular part of brachial plexus. Surgeons who perform procedures involving neoplasm or repairing trauma need to be aware of these variations.