Extra- and Intramuscular Nerve Distribution Patterns of the Muscles of the Ventral Compartment of the Forearm

Objective: This study describes the extra- and intramuscular nerve branching of muscles of the ventral compartment of forearm, thereby providing critical information on determining the points for botulinum toxin injections that would be effective at reducing muscular spasticity. Design: Twenty-three Korean and French cadavers were dissected and subjected to Modified Sihler's staining to investigate nerve entry points and intramuscular nerve arborization patterns. Nerve entry point and abundant arborizing area of each muscle were analyzed on 20 segments with reference to transverse lines obtained by dividing the forearm into ten equal divisions and a vertical line bisecting the medial and lateral halves of the forearm. Results: The nerve entry points of the first and second layers of forearm muscles were located at medial levels 3 and 2, respectively. The entry points of the median and ulnar nerves innervating the flexor digitorum profundus (third layer) were located at medial levels 4 and 3, respectively. The intramuscular regions of abundant arborization in each muscle were located one level distal to the nerve entry point. Conclusions: This study has yielded a map of nerve entry and abundant arborization of motor nerves innervating each muscle of the ventral compartment of the forearm.