Intramuscular innervations of lower leg skeletal muscles: applications in their clinical use in functional muscular transfer.

PURPOSE: This study aims to investigate nerve distribution patterns of human lower leg skeletal muscles using a modified Sihler's staining method.

METHODS: Sixteen lower leg from eight fresh adult cadavers were used in this study and all the skeletal muscles were dissected. The muscle specimens were classified according to Lim's classification. The specimens were then stained by further modified Sihler's staining technique. Data were analyzed according to research results.

RESULTS: After the staining, we found four patterns of nerve distribution in human lower leg muscles: (1) Type 1: single nerve pattern in which the nerve branches into two either running parallel to each other or radiating in a spray pattern (such as the extensor digitorum longus, extensor hallucis longus, fibularis brevis and flexor hallucis longus). (2) Type 2: double nerve pattern, one being proximal and the other being distal (such as the extensor digitorum longus, flexor digitorum longus, flexor hallucis longus). (3) Type 3: multiple branch pattern (such as the tibialis anterior, fibularis longus, gastrocnemius, soleus, tibialis anterior and popliteus).

CONCLUSION: Our modified Sihler's staining method is useful for research of large muscles and intramuscular nerves in human. These findings might provide guidance for clinicians for muscle reconstruction surgery.