Anatomical variations of the median nerve in the carpal tunnel In 246 hands in which the carpal tunnel was explored at operation, 29 variations in the course of the median nerve were found. Accessory branches at the distal portion of the tunnel werefound in 18 hands, a high division of the median nerve in seven, and accessory branches proximal to the tunnel in four. Based upon these findings and including published reports of others, the variations were classified into four groups: I-variation in the course of the thenar branch; II-accessory branches at the distal portion of the carpal tunnel; III-high divisions of the median nerve; and IV -accessory branches proximal to the carpal canal. The thenar branch variations in 100 cadaver hands (Poise!) were extraligamentous in 46 percent, subligamentous in 31 percent, and transligamentous in 23 percent. The findings emphasize the importance of approaching the median nerve from the ulnar side when opening the carpal tunnel.
Ulrich Lanz, M.D. Wiirzburg, Germany
When dividing the transverse carpal ligament to approach the deep structures in the carpal tunnel, the median nerve and its branches deserve special attention. Numerous variations of this nerve have been reported. In order to avoid surgical misadventures, a thorough knowledge of these variations is needed. The variations can be classified into four groups: Group I-variations of the course of the thenar branch; Group II-accessory branches at the distal carpal tunnel; Group III-high division of the median nerve; Group IV-accessory branches proximal to the carpal tunnel.
Observations In the 4 years ending November, 1975, over 300 explorations of the carpal tunnel were performed at the bepartment of Surgery of the University of Wiirzburg. A detailed anatomical study of the course of the median nerve was recorded in 246 hands, where such extensive dissection seemed appropriate. In 29 hands a variation of the branching of the median nerve was found. Not included in this study was the incidence of variations in the course of the thenar branch (Group I). This was reported by Poisel. 1 Accessory branches of the median Presented at the Thirty-first Annual Meeting of the American Society for Surgery of the Hand, New Orleans, La., Jan. 28-30, 1976. Received for publication Oct. 29, 1976. Reprint requests: Ulrich Lanz, M.D., siHitsklinik, 8700 WUrzburg, Germany.
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January, 1977
nerve at the distal carpal tunnel (Group II) were found in 18 cases. In seven hands a high division of the median nerve was observed (Group III). In four cases accessory branches proximal to the carpal tunnel were seen. The incidence of almost 12 percent of anatomical variations in this series is much higher than the pertinent literature suggests because the reports usually describe the findings in a single individual.
Discussion The usual branching of the median nerve is depicted in Fig. I. The motor branch becomes recurrent at the distal margin of the transverse carpal ligament before entering the thenar musculature (Fig. 2). Group I: Variations of the course of the thenar branch. In many instances the thenar branch leaves the nerve within the carpal canal. It starts from beneath the transverse carpal ligament and then bends around it (Fig. 3). It even may perforate the ligament2 (Figs. 4 and 5). In 1974 PoiseJl studied the relationship of the thenar branch to the transverse carpal ligament in 100 cadaver hands. He found the following frequencies of these three types: 46 percent extraligamentous, 31 percent subligamentous, and 23 percent transligamentous (Fig. 6). As pointed out by Spinner 3 and by Pfeiffer and Nigst,4 the trans ligamentous course of the thenar branch is clinically significant in that the nerve may be compressed within the ligament. Entin 5 drew attention to the possibility that the thenar branch may leave the median nerve at its ulnar aspect Vol. 2 No. I, pp. 44-53
Vol. 2 No. I January, 1977
Fig. 1. Regular branching of the median nerve.
Variations of median nerve in carpal tunnel
45
Fig. 3. Thenar branch leaving the median nerve within the carpal tunnel (subligamentous).
Fig. 4. Transligamentous course of the thenar branch. (After Fig. 2. Regular recurrent thenar branch (extraligamentous).
Papathassiou, B. T.: In Handchirurgie, Erlangen, 1975, VLE- Veriags-GmbH.)
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Fig. 7. Thenar branch leaving the median nerve at its ulnar aspect. (After Entin, M. A.: In Handchirurgie, Erlangen, 1975, VLE- Veriags-GmbH.)
Fig. 5. Transligamentous course of the thenar branch.
Fig. 6. Incidence of the extraligamentous, subligamentous, and transligamentous course of the thenar branch (adapted after Poisel).
(Fig. 7). Here it is endangered when the transverse carpal ligament is divided. Mannerfelt and Hybbinette 6 described another variant where the thenar branch bends around the distal margin of the transverse carpal ligament. It then runs arch like on the surface of the ligament before entering the musculature (Fig. 8). In one case we saw an analogous transligamentous course of the thenar branch (Fig. 9). The abductor pollicis brevis muscle took a very broad origin from the transverse carpal ligament, pushing the branch far ulnarly.
Fig. 8. Thenar branch on top of the transverse carpal ligament. (After Mannerfelt, L., and Hybinette, C. -H.)
Vol. 2 No . I January, 1977
Fig. 9. Transligamentous course of the thenar branch with ulnar origin.
Variations of median nerve in carpal tunnel
47
Fig. 11. Double thenar (motor) branch.
Group II: Accessory branches of the median nerve at the distal carpal tunnel. A true double motor
Fig. 10. Double thenar (motor) branch . (From Handchirurgie , Erlangen, 1975, VLE- Veriags-GmbH.)
branch seems to be a rather rare occurrence (Figs . 10 and II). More common are thin branches taking their origin from the volar (Fig. 12) or even ulnar aspect of the nerve (Fig. 13). By intraoperative nerve stimulation and exact dissection following the branches to the skin, we found the majority of these branches to be sensory. These branches seem to us especially worth preserving, as the tendency of sensory nerves in the hand to develop painful neuromata is well known. Group III: High division of the median nerve. In five of our cases the high division of the median nerve was associated with a median artery (Figs. 14 and 15). Observations of this kind were reported by Eiken, Carstarn, and Eddeland 7 in 1971 as well as by others. Both parts of the nerve have approximately the same diameter. The size of the median artery is highly variable. Fig. 16 shows a very thin one and Fig. 17 a larger one. Kessler 8 described a high division of the median nerve without a median artery with the ulnar part of the nerve being much thicker than the radial one (Fig. 18). In two patients in our series, the relation of caliber was just the opposite, with the ulnar part being thinner, providing
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Fig. 14. High di vision o f th e median nerve with median artery . (After Eiken, 0. , et a!.: In Handchirurgie, Erlangen , 1975, VLE- Veriags-GmbH. )
Fig. 12. Accessory volar (sensory) branch at the distal carpal tunnel. (From Handchirurgie, Erlangen, 1975, VLE- VerlagsGmbH .)
Fig. 13. Accessory (sensory) branch from the ulnar aspect of
Fig. 15. High division of the median nerve with median ar-
the median nerve at the distal carpal tunnel.
tery (neuroma in the ulnar part).
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Variations of median nerve in carpal tunnel
49
Fig. 16. High division of the median nerve with thin median artery .
Fig. 17. High division of the median nerve with thick median artery.
fibers only to the common digital nerve of the third interspace. Winkelman and Spinner9 recently reported a similar finding (Fig. 19). Schultz, Endler, and Huddieston 10 found an accessory lumbrical muscle between the two branches (Fig. 20) in an instance of high division of the median nerve. Group IV: Accessory branches proximal to the carp~l tunnel. In rare instances an accessory branch leaves the median nerve proximal to the carpal tunnel. Ogdenll reported one such case in 1972 (Fig. 21). The branch ran within the transverse carpal ligament joining a regular motor branch distally. In two patients we saw similar variations. In the first the accessory branch perforated the transverse carpal ligament and also joined a regular branch distally (Figs. 22 and 23, A and B). In the second the accessory branch left the median nerve at its ulnar aspect, pertorated the transverse carpalligament in the proximal third of the carpal tunnel, and joined the common digital nerve to the thumb and radial side of the index finger (Figs. 24 and 25, A and B). In its course on top of the ligament a few fibers to the skin of the thenar eminence branched off. A proximal
Fig. 18. High division of the median nerve with thick ulnar part. (After Kessler, I.: In Handchirurgie, Erlangen, 1975, VLE- Verlags-GmbH.)
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Fig. 19. High division of the median nerve with thin ulnar part. (After Winkelman, N. Z., and Spinner, M.)
)
I
Fig. 21. Accessory branch proximal to the carpal tunnel. (After Ogden, J. A.: III Handchirurgie, Erlangen, 1975, VLE- Verlags-GmbH.l
Fig. 20. High division of the median nerve with accessory
Fig. 22. Accessory branch proximal to the carpal tunnel, per-
lumbrical muscle between the two branches. (After Schultz, R. J., Endler, P. M., and Huddleston, H. D.)
forating the transverse carpal ligament. (From Handchirurgie. Erlangen, 1975, VLE- Verlags-GmbH.)
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Variations ol median nerve in carpal tunnel
51
Fig. 23. A, Same as Fig. 22, intraoperative view. B, Same as A, with the accessory branch displayed.
accessory branch also was described by Linburg and Albright 12 in 1971 (Fig. 26). In their case both motor branches entered the thenar musculature separately. We saw this type of variation in two patients.
Conclusion Our experience with variations of the median nerve in 246 cases confirms the necessity for approaching the median nerve from the ulnar side when opening the carpal tunnel. It also must be stressed that branches may arise from the ulnar side of the median nerve not only distal to the carpal tunnel but also within or proximal to it.
Summary The course and branching of the median nerve within the carpal tunnel was studied in a series of 246 hands. This paper deals with the variations of the median nerve found in this series as well as those gleaned from the literature. The variations can be classified into four groups: (1) variations ,of the course of the median nerve, (2) accessory branches at the distal carpal tunnel, (3) high division 'of the median nerve, (4) accessory branches proximal to the carpal tunnel. Our experience confirms the necessity for approaching the median nerve from the ulnar side when opening the carpal tunnel in order to avoid lacerations of variant branches.
Fig. 24. Accessory branch from the ulnar aspect of the median nerve proximal to the carpal tunnel.
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Fig. 25. A, Same as Fig. 24, intraoperative view. B. Same as A, with the accessory branch dissected out of the transverse carpal ligament.
Fig. 26. Accessory branch proximal of the carpal tunnel running directly into the thenar musculature. (After Linburg, R. M., and Albright, J. A.)
REFERENCES I. Poisel, S.: Ursprung und Verlauf des R. muscularis des Nervus digitalis palmaris communis I (N. medianus), Chir. Praxis 18: 471-474, 1974. 2. Papathanassiou, B. T.: A variant of the motor branch of the median nerve in the hand. J. Bone Joint Surg. SOB: 156-157. 1968. 3. Spinner, M.: Injuries to the major branches of the peripheral nerves of the forearm, Philadelphia, London, Toronto, 1972, W. B. Saunders Company. 4. Pfeiffer, K. M., and Nigst, H.: Ungewohnliche Befunde bei der Carpaltunnelaoperation, Handchirurgie 5: 99103, 1973. 5. Entin, M. A.: Carpal tunnel syndrome and its variants. Surg. Clin. North Am. 48: 1097, 1968. 6. Mannerfelt, L., and Hybbinette, C. -H.: Important anomaly of the thenar motor branch of the median nerve, Bull. Hosp. Joint Dis. 33: 15-21, 1972. 7. Eiken, 0., Carstam, N., Eddeland, A.: Anomalous distal branching of the median nerve. Scand. J. Plast. Reconstr. Surg. 5: 149-152, 1971. 8. Kessler, I.: Unusual distribution of the median nerve at the wrist, Clin. Orthop. 67: 124-126, 1969. 9. Winkelman, N. Z., and Spinner, M.: A variant high sensory branch of the median nerve to the third web space, Bull. Hosp. Joint Dis. 34: 161-166, 1973. 10. Schultz, R. J., Endler, P. M., and Huddleston, H. D.:
Vol. 2 No.1 January, 1977
Variations of median nerve in carpal tunnel
Anomalous median nerve and an anomalous muscle belly of the first lumbrical associated with carpal-tunnel syndrome, J. Bone Joint Surg. 55A: 1744-1746, 1973. 11. Ogden, J. A.: An unusual branch of the median nerve, J. Bone Joint Surg. 54A: 1779-1781, 1972.
53
12. Linburg, R. M., and Albright, J. A.: An anomalous branch of the median nerve, J. Bone Joint Surg. 54A: 1779-1781,1972. 13. Lanz, U.: Variationen des Nervus medianus im Bereich des Karpalkanals, Handchirurgie 7: 159-162, 1975.
From Mitchell, S. Weir: Injuries to nerves and their consequences, American Academy of Neurology Reprint Series, New York, 1965, Dover Publications, Inc., p. 24l. Thus, in one hundred and fourteen cases of nerve section which I have collected, there was but one instance of no loss of sensation or motion. These rare exceptions must, then, be referred to unusual nerve arrangements in or below the plexus, such as Krause has described in his monograph of Neural Anomalies. * *Les Anomalies dans Ie Parcours des Nerfs chez I'Homme, par W. Krause et 1. Telgmann, traduit par S. H. De La Harpe, Paris, 1869, p. 38 et seq. According to Robin, the filaments which enter the touch-corpuscles arise from terminal loops formed by the median and radial. Wenzel Gruber (Archiv fUr Anat. Phys. und Wissenschaft Med., iv. p. 501-522,1870, in Schmidt's lahrbiicher, Bd. cl. 1871, pp. 8,9.), to clear up the variety of statements in regard to anastomoses between the ulnar and median nerves, examined one hundred male and twenty-five female bodies. An anastomosis took place in ten on both sides; in eighteen on one side (right, 4; left, 14). It is, therefore, normal once in five-sixths extremities. In thirty-six cases there was one anastomotic branch, and in two a double branch. Generally, there is a branch from the median to the ulnar. Sometimes there is one from the ulnar to the median, which forms a loop with a downward convexity. In certain cases the median branch divides, one returning as a loop and one joining the ulnar. This anastomosing filament supplies the flexor profundus. It runs from the median to the ulnar below the pronator teres, and between the flexor sublimus and profundus, and either crosses or accompanies the ulnar, artery, joining the ulnar nerve from one and three-quarter inches below the epitrochlea to the lower third of the forearm. Its presence does not influence the arrangements of the palmar anastomoses. The author refers to Krause, op. cit., and to Roland Martin, Institutiones Neurologicre Holmire, 1763. Messrs. Pye-Smith, Howse, and Davies-Colley (Guy's Hospital Reports, 1870) describe as a variation from the normal, a branch between the ulnar nerve and the anterior interosseous of the median.
Ulrich Lanz, M.D. Wiirzburg, Germany
When dividing the transverse carpal ligament to approach the deep structures in the carpal tunnel, the median nerve and its branches deserve special attention. Numerous variations of this nerve have been reported. In order to avoid surgical misadventures, a thorough knowledge of these variations is needed. The variations can be classified into four groups: Group I-variations of the course of the thenar branch; Group II-accessory branches at the distal carpal tunnel; Group III-high division of the median nerve; Group IV-accessory branches proximal to the carpal tunnel.
Observations In the 4 years ending November, 1975, over 300 explorations of the carpal tunnel were performed at the bepartment of Surgery of the University of Wiirzburg. A detailed anatomical study of the course of the median nerve was recorded in 246 hands, where such extensive dissection seemed appropriate. In 29 hands a variation of the branching of the median nerve was found. Not included in this study was the incidence of variations in the course of the thenar branch (Group I). This was reported by Poisel. 1 Accessory branches of the median Presented at the Thirty-first Annual Meeting of the American Society for Surgery of the Hand, New Orleans, La., Jan. 28-30, 1976. Received for publication Oct. 29, 1976. Reprint requests: Ulrich Lanz, M.D., siHitsklinik, 8700 WUrzburg, Germany.
44
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Univer-
January, 1977
nerve at the distal carpal tunnel (Group II) were found in 18 cases. In seven hands a high division of the median nerve was observed (Group III). In four cases accessory branches proximal to the carpal tunnel were seen. The incidence of almost 12 percent of anatomical variations in this series is much higher than the pertinent literature suggests because the reports usually describe the findings in a single individual.
Discussion The usual branching of the median nerve is depicted in Fig. I. The motor branch becomes recurrent at the distal margin of the transverse carpal ligament before entering the thenar musculature (Fig. 2). Group I: Variations of the course of the thenar branch. In many instances the thenar branch leaves the nerve within the carpal canal. It starts from beneath the transverse carpal ligament and then bends around it (Fig. 3). It even may perforate the ligament2 (Figs. 4 and 5). In 1974 PoiseJl studied the relationship of the thenar branch to the transverse carpal ligament in 100 cadaver hands. He found the following frequencies of these three types: 46 percent extraligamentous, 31 percent subligamentous, and 23 percent transligamentous (Fig. 6). As pointed out by Spinner 3 and by Pfeiffer and Nigst,4 the trans ligamentous course of the thenar branch is clinically significant in that the nerve may be compressed within the ligament. Entin 5 drew attention to the possibility that the thenar branch may leave the median nerve at its ulnar aspect Vol. 2 No. I, pp. 44-53
Vol. 2 No. I January, 1977
Fig. 1. Regular branching of the median nerve.
Variations of median nerve in carpal tunnel
45
Fig. 3. Thenar branch leaving the median nerve within the carpal tunnel (subligamentous).
Fig. 4. Transligamentous course of the thenar branch. (After Fig. 2. Regular recurrent thenar branch (extraligamentous).
Papathassiou, B. T.: In Handchirurgie, Erlangen, 1975, VLE- Veriags-GmbH.)
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Fig. 7. Thenar branch leaving the median nerve at its ulnar aspect. (After Entin, M. A.: In Handchirurgie, Erlangen, 1975, VLE- Veriags-GmbH.)
Fig. 5. Transligamentous course of the thenar branch.
Fig. 6. Incidence of the extraligamentous, subligamentous, and transligamentous course of the thenar branch (adapted after Poisel).
(Fig. 7). Here it is endangered when the transverse carpal ligament is divided. Mannerfelt and Hybbinette 6 described another variant where the thenar branch bends around the distal margin of the transverse carpal ligament. It then runs arch like on the surface of the ligament before entering the musculature (Fig. 8). In one case we saw an analogous transligamentous course of the thenar branch (Fig. 9). The abductor pollicis brevis muscle took a very broad origin from the transverse carpal ligament, pushing the branch far ulnarly.
Fig. 8. Thenar branch on top of the transverse carpal ligament. (After Mannerfelt, L., and Hybinette, C. -H.)
Vol. 2 No . I January, 1977
Fig. 9. Transligamentous course of the thenar branch with ulnar origin.
Variations of median nerve in carpal tunnel
47
Fig. 11. Double thenar (motor) branch.
Group II: Accessory branches of the median nerve at the distal carpal tunnel. A true double motor
Fig. 10. Double thenar (motor) branch . (From Handchirurgie , Erlangen, 1975, VLE- Veriags-GmbH.)
branch seems to be a rather rare occurrence (Figs . 10 and II). More common are thin branches taking their origin from the volar (Fig. 12) or even ulnar aspect of the nerve (Fig. 13). By intraoperative nerve stimulation and exact dissection following the branches to the skin, we found the majority of these branches to be sensory. These branches seem to us especially worth preserving, as the tendency of sensory nerves in the hand to develop painful neuromata is well known. Group III: High division of the median nerve. In five of our cases the high division of the median nerve was associated with a median artery (Figs. 14 and 15). Observations of this kind were reported by Eiken, Carstarn, and Eddeland 7 in 1971 as well as by others. Both parts of the nerve have approximately the same diameter. The size of the median artery is highly variable. Fig. 16 shows a very thin one and Fig. 17 a larger one. Kessler 8 described a high division of the median nerve without a median artery with the ulnar part of the nerve being much thicker than the radial one (Fig. 18). In two patients in our series, the relation of caliber was just the opposite, with the ulnar part being thinner, providing
48
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Lanz
Fig. 14. High di vision o f th e median nerve with median artery . (After Eiken, 0. , et a!.: In Handchirurgie, Erlangen , 1975, VLE- Veriags-GmbH. )
Fig. 12. Accessory volar (sensory) branch at the distal carpal tunnel. (From Handchirurgie, Erlangen, 1975, VLE- VerlagsGmbH .)
Fig. 13. Accessory (sensory) branch from the ulnar aspect of
Fig. 15. High division of the median nerve with median ar-
the median nerve at the distal carpal tunnel.
tery (neuroma in the ulnar part).
Vol. 2 No. I January, 1977
Variations of median nerve in carpal tunnel
49
Fig. 16. High division of the median nerve with thin median artery .
Fig. 17. High division of the median nerve with thick median artery.
fibers only to the common digital nerve of the third interspace. Winkelman and Spinner9 recently reported a similar finding (Fig. 19). Schultz, Endler, and Huddieston 10 found an accessory lumbrical muscle between the two branches (Fig. 20) in an instance of high division of the median nerve. Group IV: Accessory branches proximal to the carp~l tunnel. In rare instances an accessory branch leaves the median nerve proximal to the carpal tunnel. Ogdenll reported one such case in 1972 (Fig. 21). The branch ran within the transverse carpal ligament joining a regular motor branch distally. In two patients we saw similar variations. In the first the accessory branch perforated the transverse carpal ligament and also joined a regular branch distally (Figs. 22 and 23, A and B). In the second the accessory branch left the median nerve at its ulnar aspect, pertorated the transverse carpalligament in the proximal third of the carpal tunnel, and joined the common digital nerve to the thumb and radial side of the index finger (Figs. 24 and 25, A and B). In its course on top of the ligament a few fibers to the skin of the thenar eminence branched off. A proximal
Fig. 18. High division of the median nerve with thick ulnar part. (After Kessler, I.: In Handchirurgie, Erlangen, 1975, VLE- Verlags-GmbH.)
50
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Fig. 19. High division of the median nerve with thin ulnar part. (After Winkelman, N. Z., and Spinner, M.)
)
I
Fig. 21. Accessory branch proximal to the carpal tunnel. (After Ogden, J. A.: III Handchirurgie, Erlangen, 1975, VLE- Verlags-GmbH.l
Fig. 20. High division of the median nerve with accessory
Fig. 22. Accessory branch proximal to the carpal tunnel, per-
lumbrical muscle between the two branches. (After Schultz, R. J., Endler, P. M., and Huddleston, H. D.)
forating the transverse carpal ligament. (From Handchirurgie. Erlangen, 1975, VLE- Verlags-GmbH.)
Vol. 2 No.1
January, 1977
Variations ol median nerve in carpal tunnel
51
Fig. 23. A, Same as Fig. 22, intraoperative view. B, Same as A, with the accessory branch displayed.
accessory branch also was described by Linburg and Albright 12 in 1971 (Fig. 26). In their case both motor branches entered the thenar musculature separately. We saw this type of variation in two patients.
Conclusion Our experience with variations of the median nerve in 246 cases confirms the necessity for approaching the median nerve from the ulnar side when opening the carpal tunnel. It also must be stressed that branches may arise from the ulnar side of the median nerve not only distal to the carpal tunnel but also within or proximal to it.
Summary The course and branching of the median nerve within the carpal tunnel was studied in a series of 246 hands. This paper deals with the variations of the median nerve found in this series as well as those gleaned from the literature. The variations can be classified into four groups: (1) variations ,of the course of the median nerve, (2) accessory branches at the distal carpal tunnel, (3) high division 'of the median nerve, (4) accessory branches proximal to the carpal tunnel. Our experience confirms the necessity for approaching the median nerve from the ulnar side when opening the carpal tunnel in order to avoid lacerations of variant branches.
Fig. 24. Accessory branch from the ulnar aspect of the median nerve proximal to the carpal tunnel.
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Fig. 25. A, Same as Fig. 24, intraoperative view. B. Same as A, with the accessory branch dissected out of the transverse carpal ligament.
Fig. 26. Accessory branch proximal of the carpal tunnel running directly into the thenar musculature. (After Linburg, R. M., and Albright, J. A.)
REFERENCES I. Poisel, S.: Ursprung und Verlauf des R. muscularis des Nervus digitalis palmaris communis I (N. medianus), Chir. Praxis 18: 471-474, 1974. 2. Papathanassiou, B. T.: A variant of the motor branch of the median nerve in the hand. J. Bone Joint Surg. SOB: 156-157. 1968. 3. Spinner, M.: Injuries to the major branches of the peripheral nerves of the forearm, Philadelphia, London, Toronto, 1972, W. B. Saunders Company. 4. Pfeiffer, K. M., and Nigst, H.: Ungewohnliche Befunde bei der Carpaltunnelaoperation, Handchirurgie 5: 99103, 1973. 5. Entin, M. A.: Carpal tunnel syndrome and its variants. Surg. Clin. North Am. 48: 1097, 1968. 6. Mannerfelt, L., and Hybbinette, C. -H.: Important anomaly of the thenar motor branch of the median nerve, Bull. Hosp. Joint Dis. 33: 15-21, 1972. 7. Eiken, 0., Carstam, N., Eddeland, A.: Anomalous distal branching of the median nerve. Scand. J. Plast. Reconstr. Surg. 5: 149-152, 1971. 8. Kessler, I.: Unusual distribution of the median nerve at the wrist, Clin. Orthop. 67: 124-126, 1969. 9. Winkelman, N. Z., and Spinner, M.: A variant high sensory branch of the median nerve to the third web space, Bull. Hosp. Joint Dis. 34: 161-166, 1973. 10. Schultz, R. J., Endler, P. M., and Huddleston, H. D.:
Vol. 2 No.1 January, 1977
Variations of median nerve in carpal tunnel
Anomalous median nerve and an anomalous muscle belly of the first lumbrical associated with carpal-tunnel syndrome, J. Bone Joint Surg. 55A: 1744-1746, 1973. 11. Ogden, J. A.: An unusual branch of the median nerve, J. Bone Joint Surg. 54A: 1779-1781, 1972.
53
12. Linburg, R. M., and Albright, J. A.: An anomalous branch of the median nerve, J. Bone Joint Surg. 54A: 1779-1781,1972. 13. Lanz, U.: Variationen des Nervus medianus im Bereich des Karpalkanals, Handchirurgie 7: 159-162, 1975.
From Mitchell, S. Weir: Injuries to nerves and their consequences, American Academy of Neurology Reprint Series, New York, 1965, Dover Publications, Inc., p. 24l. Thus, in one hundred and fourteen cases of nerve section which I have collected, there was but one instance of no loss of sensation or motion. These rare exceptions must, then, be referred to unusual nerve arrangements in or below the plexus, such as Krause has described in his monograph of Neural Anomalies. * *Les Anomalies dans Ie Parcours des Nerfs chez I'Homme, par W. Krause et 1. Telgmann, traduit par S. H. De La Harpe, Paris, 1869, p. 38 et seq. According to Robin, the filaments which enter the touch-corpuscles arise from terminal loops formed by the median and radial. Wenzel Gruber (Archiv fUr Anat. Phys. und Wissenschaft Med., iv. p. 501-522,1870, in Schmidt's lahrbiicher, Bd. cl. 1871, pp. 8,9.), to clear up the variety of statements in regard to anastomoses between the ulnar and median nerves, examined one hundred male and twenty-five female bodies. An anastomosis took place in ten on both sides; in eighteen on one side (right, 4; left, 14). It is, therefore, normal once in five-sixths extremities. In thirty-six cases there was one anastomotic branch, and in two a double branch. Generally, there is a branch from the median to the ulnar. Sometimes there is one from the ulnar to the median, which forms a loop with a downward convexity. In certain cases the median branch divides, one returning as a loop and one joining the ulnar. This anastomosing filament supplies the flexor profundus. It runs from the median to the ulnar below the pronator teres, and between the flexor sublimus and profundus, and either crosses or accompanies the ulnar, artery, joining the ulnar nerve from one and three-quarter inches below the epitrochlea to the lower third of the forearm. Its presence does not influence the arrangements of the palmar anastomoses. The author refers to Krause, op. cit., and to Roland Martin, Institutiones Neurologicre Holmire, 1763. Messrs. Pye-Smith, Howse, and Davies-Colley (Guy's Hospital Reports, 1870) describe as a variation from the normal, a branch between the ulnar nerve and the anterior interosseous of the median.
