Axons from the median and ulnar nerves can pass to each other through aberrant connections between them. Multiple interconnections between the nerves may provide a detour route for nerve fibres going to the hand. We investigated the incidence of variations and the associations between them in 90 cadaveric upper limbs. In 91% of upper limbs, one to five variations were found, with several statistically significant associations. The contribution of the C8 nerve to the lateral cord was positively associated with an accessory contribution of the lateral cord to the ulnar nerve. The latter variation showed positive association with the occurrence of any of the variations in the hand itself. Ulnar innervation of the superficial head of the flexor pollicis brevis was positively associated with the Riche-Cannieu communication. The co-existence of the variations and their associations may be the explanation for unusual clinical findings related to median and ulnar conduction, which appear contrary to anatomical knowledge.
AjmaniML.Variations in the motor nerve supply of the thenar and hypothenar muscles of the hand. J Anat. 1996, 189(Pt 1): 145–50.
2.
AmoiridisG.Median-ulnar nerve communications and anomalous innervation of the intrinsic hand muscles: an electrophysiological study. Muscle Nerve. 1992, 15: 576–9.
3.
BölükbaşiOTurgutMAkyolA.Ulnar to median nerve anastomosis in the palm (Riches-Cannieu anastomosis). Neurosurg Rev. 1999, 22: 138–9.
4.
BrooksHS.Variations in the nerve supply of the flexor brevis pollicis muscle. J Anat Physiol. 1886, 20: 641–4.
5.
DayMHNapierJR. The two heads of flexor pollicis brevis. J Anat. 1961, 95: 123–30.
6.
Don GriotJPZuidamJMvan KootenEOProséLPHageJJ.Anatomic study of the ramus communicans between the ulnar and median nerves. J Hand Surg Am. 2000, 25: 948–54.
7.
ErdemHRErgunSErturkCOzelS.Electrophysiological evaluation of the incidence of Martin-Gruber anastomosis in healthy subjects. Yonsei Med J. 2002, 43: 291–5.
8.
FalconerDSpinnerM.Anatomic variations in the motor and sensory supply of the thumb. Clin Orthop Relat Res. 1985, 195: 83–96.
9.
FerrariGPGilbertA.The superficial anastomosis on the palm of the hand between the ulnar and median nerves. J Hand Surg Br. 1991, 16: 511–4.
10.
GuptaSMichelsen-JostH.Anatomy and function of the thenar muscles. Hand Clin. 2012, 28: 1–7.
11.
GutmannL.AAEM minimonograph #2: important anomalous innervations of the extremities. Muscle Nerve. 1993, 16: 339–47.
JohnsonEOVekrisMDemestichaTSoucacosPN.Neuroanatomy of the brachial plexus: normal and variant anatomy of its formation. Surg Radiol Anat. 2010, 32: 291–7.
15.
KerrAT.The brachial plexus of nerves in man, the variations in its formation and branches. Am J Anat. 1918, 23: 285–395.
16.
KimDHChoYJTielRLKlineDG.Outcomes of surgery in 1019 brachial plexus lesions treated at Louisiana State University Health Sciences Center. J Neurosurg. 2003, 98: 1005–16.
17.
KimuraJMurphyMJVardaDJ.Electrophysiological study of anomalous innervation of intrinsic hand muscles. Arch Neurol. 1976, 33: 842–4.
18.
KimuraIAyyarDRLippmannSM.Electrophysiological verification of the ulnar to median nerve communications in the hand and forearm. Tohoku J Exp Med. 1983, 141: 269–74.
19.
LeibovicSJHastingsH.Martin-Gruber revisited. J Hand Surg Am. 1992, 17: 47–53.
20.
Meenakshi-SundaramSSundarBArunkumarMJ.Marinacci communication: an electrophysiological study. Clin Neurophysiol. 2003, 114: 2234–7.
21.
OhSJClaussenGCAhmadBK.Double anastomosis of median-ulnar and ulnar-median nerves: report of an electrophysiologically proven case. Muscle Nerve. 1995, 18: 1332–4.
22.
SachsGMRaynorEMShefnerJM.The all ulnar motor hand without forearm anastomosis. Muscle Nerve. 1995, 18: 309–13.
23.
SarikciogluLSindelMOzkaynakSAydinH.Median and ulnar nerve communication in the forearm: an anatomical and electrophysiological study. Med Sci Monit. 2003, 9: BR351–6.
24.
SimonettiS.Electrophysiological study of forearm sensory fiber crossover in Martin-Gruber anastomosis. Muscle Nerve. 2001, 24: 380–6.
25.
StancićMFMićovićVPotocnjakM.The anatomy of the Berrettini branch: implications for carpal tunnel release. J Neurosurg. 1999, 91: 1027–30.
26.
SucherBMSchreiberAL.Carpal tunnel syndrome diagnosis. Phys Med Rehabil Clin N Am. 2014, 25: 229–47.
27.
SulaimanSSoamesRLambC.An anatomical study of the superficial palmar communicating branch between the median and ulnar nerves. J Hand Surg Eur. 2016, 41: 191–197.
28.
TagilSMBozkurtMCOzçakarLErsoyMTekdemirIElhanA.Superficial palmar communications between the ulnar and median nerves in Turkish cadavers. Clin Anat. 2007, 20: 795–8.
29.
UchidaYSugiokaY.Electrodiagnosis of Martin-Gruber connection and its clinical importance in peripheral nerve surgery. J Hand Surg Am. 1992, 17: 54–9.
30.
Van DijkJG. Anomalies of innervation. In: KimuraJDaubeJRMauguièreF (Eds.) Handbook of clinical neurophysiology. Amsterdam, Elsevier, 2006, Vol. 7: 311–33.
