Innervation Pattern of Lumbrical Muscles of the Foot in Human Fetuses.

BACKGROUND: The main objective of this study is to describe the innervation patterns of foot lumbrical muscles and its morphological properties in human fetuses. Another objective is to define the communicating branches between medial (MPN) and lateral (LPN) plantar nerves, which play a part in innervation of those muscles.

METHODS: Thirty formalin-fixed fetuses (13 males - 17 females) with a mean gestational age of 25.5±3.8 (range, 18-36) weeks within the inventory of Mersin University Faculty of Medicine Anatomy Department were bilaterally dissected. Innervation pattern of lumbricals and the communicating branches between MPN and LPN were detected and photographed.

RESULTS: No variations were seen within lumbrical numbers. Out of 60, first lumbrical started directly from flexor digitorum longus tendon in 48 and flexor hallucis longus slips in addition to flexor digitorum longus tendon in 12 sides. 55 feet had classic innervation pattern of lumbricals while 5 had variations. No communicating branches were seen in 48 sides whereas 12 sides had connection.

CONCLUSIONS: This study classified innervation pattern of foot lumbricals and defined 2 new innervation types. During surgeries on foot and ankle region in neonatal and early childhood terms, awareness of the communicating branches between MPN and LPN and innervation of intrinsic muscles of the foot such as lumbricals might aid in preventing possible complications.