RESUMO
Objective To observe and study the distribution and histological feature of the fascicular groups to deltoid muscle in axillary nerve at the level of quadrilateral zone. Methods 12 adult human cadavers (24 upper limbs)embalmed by formalin were used,, and microsurgical longitudinal contradissection of the axillary nerves by tracing their terminal branches were processed. At the level of quadrilateral zone,distrabution of the fscicular groups to deltoid muscle in the never trunk were recorded and their diameters were measured;Another 6 upper extremities (3 right and 3 left) of fresh-frozen human cadavers were obtained.Axillary nerves and their fascicular groups were exposured, and the segments at the level of qusdrilateral zone gotten, then histological cross section was done, acetycholinesterase (ACHE) stained with the method of Karnovsky Roots and myelin stained with the method of Loyezs. Defferent never fibres were distinguished under microscope and the fiber number was counted with IAS . Results At the level of quadrilateral zone,fasciculars were divided into two groups.The fascicular group of anterior branch to deltoid muscle was in the lateral of the nerve trunk . Its cross sectional area was (2.449?1.327)mm2 ,occupied 55.4%?9.3%of the axillary nerve trunk ;Its most fibers were motor fibers;The number of fibers is (2112?631), occupied 45.6 %?1.1%of all fibers of axillary nerve . Conclusions In the treatment of root avulsion of brachial plexus injury, selective suture donor nerve with the lateral fascicular group should be processed to repair the function of shoulder abduction,fibers loss would be reduced and rate of functional restoration improved .