Anatomical variability of median nerve formation in human foetuses in clinical aspect.

BACKGROUND: The median nerve is an important nerve leaving the brachial plexus. Median nerve damages may result from tunnel syndromes or injuries. The nerve anatomical variants are of great clinical importance in hand surgery.

OBJECTIVES: Clinical evaluation of median nerve divergence from brachial plexus morphological variability in foetal period.

MATERIAL AND METHODS: The material consisted of 220 brachial plexus sections derived from 110 foetuses aged 14-32 weeks of foetal life (50 females and 60 males, in CRL: 80-233 mm). The survey incorporated the following methods: dissection, anthropological, image digital acquisition, Image J computer transformation system, GIMP programme and statistical methods. Typology assessment was based on 0/1 system. Sexual dimorphism and symmetry were examined.

RESULTS: Median nerve left directly lateral cord in 5 cases. In 59 (26.81%) plexuses, anterior division of middle trunk co-created median nerves anomalies. The total of 9 types of anterior division of middle trunk as well as of median nerve were distinguished. Median nerve double root leaving lateral cord was observed in 10 (9.09%) cases, whereas triple lateral root was seen in one case. In 1/3 of the examined plexuses, median nerve roots combined to form the nerve beneath humeral bone head and even in ½ of the bone distal length (type II and III). Type II prevailed more often on the left side.

CONCLUSIONS: Median nerve roots as well as the median nerve itself are characteristic for significant morphological variability. Nerve roots low junction into median nerve is clinically favourable as it can prevent nerve damage during injuries.