Martin Gruber Anastomosis
Original Editor - Nehal Shah
Top Contributors - Nehal Shah and Ewa Jaraczewska
Introduction[edit | edit source]
Anomalous means deviated from normal / routine. Anomalous innervations are routinely a normal occurrence. But if these are not recognised, they may be mistaken for technical pitfall or an actual pathology which may not be present [1] Nerve communication between the median and ulnar nerves in the forearm, is known as Martin-Gruber anastomosis. This implies that nerve fascicles from Median nerve transfers to Ulnar nerve[2]
The prevalence of Martin Gruber Anastomosis (MGA) is between 3.3 to 40% of population [1]with a prevalence of 11.6 % in Indian population [3]Median to Ulnar nerve communication was first described by Martin in 1763 [4]who proposed the possibility of such a communication. This finding was finally confirmed after 100 years by Gruber in in 1870 [5]
Innervation Pattern of Hand[edit | edit source]
| Median Nerve | Ulnar Nerve |
|---|---|
| Abductor Pollicis Brevis | Abductor Digiti Minimi |
| Opponens Pollicis Brevis | Flexor Digiti Minimi |
| Flexor Pollicis Brevis | Opponens Digiti Minimi |
| 1st and 2nd Lumbrical | 3rd and 4th Lumbrical |
| Dorsal and Palmar Interossei | |
| Deep Head of Flexor Pollices Brevis | |
| Adductor Pollices |
Studies suggest that this standard pattern is seen in 33% of cases[6]
Common Patterns of Anamolous Innervations of Median and Ulnar nerves[edit | edit source]
Due to the complexity of anatomy of upper extremity especially the brachial plexus and strategical anatomical zones as cubital tunnel, Guyon canal, carpal tunnel, results in anomalous branching of nerves. They may form anastomosis [2]To understand them better, Mennerfelt et al divided Ulnar nerve in four zones [7]
- ANOMALOUS PATTERN OF INNERVATION IN ZONE I - Usually Flexor Carpi Ulnaris (FCU) muscle innervates at the level of medial epicondyle of Humerus. But it can innervate 4-7 cms proximal to FCU (Sunderland & Hughes, 1946)
- ANOMALOUS PATTERN OF INNERVATION IN ZONE II -
- Isolated branch of Ulnar nerve arises in the middle of the forearm and runs down to supply Ulnar aspect of 4th finger (Turner 1874)
- Dorsal Ulnar Cutaneous nerve which usually arises about 5 cms above wrist
- Variation in the level of innervation of FCU and Flexor Digitorum Profundus IV & V (Sunderland and Hoges 1946)
- Martin Gruber Anastomosis - Anastomosis between Median and Ulnar nerve where there are communicating branch from Median nerve to Ulnar nerve. This is the main anomalous innervation in Zone II
- ANOMALOUS PATTERN OF INNERVATION IN ZONE III - Unusual distribution of Dorsal Ulnar Cutaneous nerve enclosing Pisiform bone (Kaplan 1963)
- ANOMALOUS PATTERN OF INNERVATION IN ZONE IV -
- Double innervation of First Dorsal Interosseus - both by Median and Ulnar nerves (Murphey, Kirklin and Finlayson (1946))
- Double innervation of Lumbricals - Double innervation of any of the Lumbricals by Median and Ulnar nerve (Brooke 1887 and Riche 1897)
- Thenar eminence supplied entirely or partly by Ulnar neve
- Anastomosis between deep ulnar branches and motor branches of the median nerve in the radial part of the palm of the hand.
- Hypothenar muscles innervated entirely or partly by the median nerve.
Resources[edit | edit source]
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References[edit | edit source]
- ↑ 1.0 1.1 Aziz Saba EK. Electrophysiological study of Martin—Gruber anastomosis in a sample of Egyptians. Egyptian Rheumatology and Rehabilitation. 2017 Oct;44:153-8.
- ↑ 2.0 2.1 Cavalheiro CS, Razuk Filho M, Pedro G, Caetano MF, Vieira LA, Caetano EB. Clinical repercussions of Martin-Gruber anastomosis: anatomical study. Revista Brasileira de Ortopedia. 2016 Mar;51:214-23.
- ↑ Kaur N, Singla RK, Kullar JS. Martin–Gruber Anastomosis-A cadaveric study in north indian population. Journal of Clinical and Diagnostic Research: JCDR. 2016 Feb;10(2):AC09.
- ↑ Martin R. Tal om nervers allmänna egenskaper i människans kropp.
- ↑ Gruber W. Ueber die verbindung des nervus medianus mit dem nervus ulnaris am unterarme des menshen und der saugethiere. Arch Anat Phisiol. 1870;37:501.
- ↑ Rowntree T. Anomalous innervation of the hand muscles. The Journal of Bone and Joint Surgery. British volume. 1949 Nov;31(4):505-10.
- ↑ Mannerfelt L. Studies on the hand in ulnar nerve paralysis: a clinical-experimental investigation in normal and anomalous innervation. Acta Orthopaedica Scandinavica. 1966 Mar 1;37(sup87):3-176.
