Abstract
Introduction Variations in the formation and in the branching pattern of the brachial plexus are
common. Numerous anastomotic variations between the musculocutaneous nerve (MCN) and
the median nerve (MN) have been reported and could be implicated in a wide range of
sensory and motor dysfunctions.
Objective To report an uncommon case of an anastomotic variation between the MN and the MCN
with a rare absence of the lateral cutaneous nerve of forearm (LCNF).
Material and Methods A dissection of a male cadaver was performed at the Morphology Department of the
Universidade Federal do Ceará, Fortaleza, state of Ceará, Brazil. The brachial plexus
was exposed.
Results It was observed that the MCN, after its origin in the lateral fasciculus of the brachial
plexus, anastomoses with the MN in the middle third of the arm. It diverges from the
most prevalent anatomical pattern, in which the MCN continues to pass distally beneath
the brachii biceps, originating the LCNF. In this case, the MCN does not emit its
main terminal branch, the LCNF, which innervates the lateral portion of the skin of
the forearm. In the present case, the innervation of the lateral portion of the skin
of the forearm is provided by radial nerve branches. The reported case has practical
implications, since the absence of the LCNF could cause hypoesthesia in the skin of
the forearm.
Conclusion Thus, the knowledge of the formation and of the branching pattern of the brachial
plexus is clinically important for the correct clinical interpretation of the sensory
and motor disorders of the upper limbs caused by peripheral nerve injuries, as well
as for planning surgical procedures to correct upper limb traumas.
Keywords
upper limb - median nerve - musculocutaneous nerve - lateral cutaneous nerve of forearm
- brachial plexus
