Purpose
The restoration of elbow flexion is of primary importance in the management of patients
with brachial plexus injuries. Superior functional outcomes via fascicle transfer
from the ulnar and median nerves have resulted in this transfer being considered the
mainstay of recovery of elbow flexion in patients with intact C8 and T1 function.
An understanding of the anatomy of the musculocutaneous nerve (MCN) and its branching
pattern is key while performing these transfers.
Methods
A prospective cohort study was conducted in patients who underwent nerve transfer
for the restoration of elbow flexion following a traumatic brachial plexus injury.
The anatomic course and branching pattern of the MCN were recorded in eligible cases,
both as a line diagram and using intraoperative photographs.
Results
One hundred fifty patients underwent nerve transfer for the restoration of elbow flexion
following an injury to the brachial plexus. The MCN in 138 patients (92%) was found
to pierce the coracobrachialis muscle before emerging lateral to it. One hundred thirty-four
patients (89.3%) demonstrated the “classical” anatomy. One hundred fifteen patients
(76.6%) had a single primary branch to the biceps, whereas 25 patients (16.6%) demonstrated
a discrete motor branch to each head. One hundred thirty-three dissections (88.6%)
revealed a single muscular branch to the brachialis arising posteromedially from the
MCN, distal to the origin of the branch to the biceps brachii. Notable unreported
variations, such as the MCN penetrating the biceps as it descended, multiple brachialis
branches, and trifurcation of divisions of the MCN, were documented.
Conclusions
Variations in MCN anatomy are quite common, and even unreported variations can be
encountered.
Clinical relevance
Exploration of the MCN and its branches for nerve transfers requires knowledge of
these anatomic variations and vigilance to prevent inadvertent injuries while dissecting
them for nerve transfer surgery.
Key words
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Article info
Publication history
Published online: September 02, 2022
Accepted:
July 13,
2022
Received:
October 31,
2021
Footnotes
No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
Identification
Copyright
© 2022 by the American Society for Surgery of the Hand. All rights reserved.
