Vol. 10A, No. 6, Part 1November 1985 Median artery in carpal tunnel syndrome

drome secondary to thrombosis of a persistent medianartery. Ann Acad Med Singapore 9:118-21, 1980

4. Edwards EA: Organization of the small arteries of thehand and digits. Am J Surg 99:837-46, 1960

5. Pecket P, Gloobe H, Nathan H: Variations in the arteriesof the median nerve. Clin Orthop 97:144-7, 1973

6. Burnham PJ: Acute carpal tunnel syndrome. Arch Surg87:645-6, 1963

7. De Abreu LB, Moreira RG: Median-nerve compressionat the wrist. J Bone Joint Surg [Am] 4:1426-7, 1958

8. Jackson IT, Campbell JC: An unusual cause of carpaltunnel syndrome. J Bone Joint Surg [Br] 52:330-3, 1970

9. Levy M, Pauker M: Carpal tunnel syndrome due to

thrombosed persisting median artery. A case report. Hand10:65-8, 1978

10. Maxwell JA, Kepes JJ, Ketchum LD: Acute catpal tunnelsyndrome secondary to thrombosis of a persistent medianartery. J Neurosurg 38:774-7, 1973

11. Chalmers J: Unusualcauses of peripheral nerve compres-sion. Hand 10:168-75, 1978

12. Lavey EB, Pearl RM: Patent median artery as a causeof carpal tunnel syndrome. Ann Plast Surg 7:236-8, 1981

13. Mauersberger W, Meese W: Carpal tunnel syndromecaused by the persistence of the median artery. Neuro-chirugia (Stuggt) 18:15-9, 1975

Surgical significance of thegroup of the ulnar nerve in

motor fascicularthe forearm

The topography of the fascicular group of the ulnar nerve at the wrist and forearm was studiedfocusing on the motor (muscle) fascicular group. In 109 of 111 specimens studied (98%), motor fascicular group of the ulnar nerve is located at the ulnar dorsal or straight dorsal positionat the wrist and the distal forearm. This motor fascicular group may be identified as a distinctentity~up to 90 mm proximal from the level of the radial styloid. The relatively constant location

of the motor fascicular group is significant since most lacerations of the major peripheral nervesof the upper extremity are at the distal forearm or the wrist. In the surgical treatment of acutelacerations of the ulnar nerve at these levels, one should direct special attention to the correctidentification, matching, and alignment of the motor fascicular group to enhance reinnervation

of the intrinsic muscles of the hand. (J HAND SURG 10A:867"72, 1985.)

Jimmy A. Chow, L.T.C., M.C., Allen L. Van Beek, M.D.,

David L. Meyer, L.T.C., M.C., and Martha C. Johnson, Ph.D.

Washington, D.C., and Bethesda, Md.

From the Hand Surgery Unit, Divisions Of Orthopedics and PlasticSurgery, Walter Reed Army Medical Center, Washington, D.C.,and the Departments of Surgery and Anatomy, Armed Forces Med-ical School, Uniformed Services University of Health Sciences,Bethesda, Md.

Presented at the Thirty-Ninth Annual Meeting of the American So-cie .ty for Surgery of the Hand, Atlanta, Ga., February 1984.

Received for publication Jan. 4, 1985; accepted in revised form March8, 1985.

Reprint requests: Jimmy A. Chow, M.D., F.A.C.S., Plastic SurgeryService, Walter Reed Army Medical Center, Washington, D.C.20307.

The opinions or assertions contained herein are the private views dfthe authors and are not to be construed as official or as reflectingthe views of the Department of the Army or the Department ofDefense.

¯ n the surgical treatment of traumatic le-

sions of mixed peripheral nerves, the distal forearm isprivileged anatomically for two reasons: (1) The fas-cicular groups are well defined, and (2) these fasciculargroups remain as distinct anatomic entities for consid-erable distances.

We studied the topography of the fascicular group of-the ulnar nerve at the wrist and forearm, focusing on

the location and course of the motor (muscle) fasciculargroup.

Material and methods

A" total of 111 upper extremities were used inthis study: 45 were fresh-frozen or refrigerated spec-

THEJOURNAL OF HANDSURGERY 867

868 Chow et al. The Journal ofHAND SURGERY

, ULNAR

DORI25MM

45MM

Fig. 1. Histologic sections of the left ulnar nerve at 20 mm intervals apart. A is at 25 mm proximalto the radial styloid and B is at the 45 mm level. The motor fascicular group (M) is located at theulnar dorsal position. Note the intraneural epineufium (arrows) that separates the fascicular groups.

Fig. 2, A-D. Conventional light-photography of cross-sect~onal surface of consecutive segmentsof the left ulnar nerve at 5 mm intervals apart. A is at 50 mm proximal to the radial styloid.

Vol. 10A, No. 6, Part 1November 1985 Surgical significance of motor fascicular group 869

Fig. 2, E-G. Conventional light photography of cross-sectional surface of consecutive segmentsof the left ulnar nerve at 5 mm intervals apart. G is at..the 80 mm level. Note the motor fasciculargroup (M) at the ulnar dorsal position. This is separated from the s~nsory fascicular group (S) bythe intraneural epineurium (arrows).

~mens and 66 were formalin-preserved anatomic ma-terial. "

Micr’osurgical longitudinal dissections of the fascic-ular groups of the ulnar nerve were performed in 17fresh-frozen specimens by tracing the terminal branchesproximally from the hand. The fascicular groups thatgive rise to the dorsal cutaneous branch at the distalforearm and the muscular branches at the proximal fore-arm were also followed in the proximal direction usinga similar technique.

The following serial section studies were performedwith fresh anatomic specimens.

Standard histologie sections. The pattern of the fas-cicular group of the ulnar nerve was studied in 10 fresh-frozen specimens by means t)f standard histologic sec-tions. Attention was directed to the location of the motorfascicular group in the serial sections. Hematoxylin-eosin and Masson trichrome stains were used (Fig. 1).

Special light photography. In 16 fresh-frozen spec-

imens, conventional photographs of the cross-sectionalsurface of serial sections of the ulnar nerve were ob-tained by means of a camera with a bellows attachment.The fascicular groups were clearly seen in the photo-graphs (Fig. 2).

Scanning electron microscopy. The topography ofthe fascicular groups of the ulnar nerve was studied intwo upper extremity specimens. Scanning electron mi-croscopy was previously described.~

Additional information on the location of the motorfascicular group of the ulnar nerve in the distal forearmwas obtained from 66 upper extremity specimens offormalin-preserved cadavers.

Results

In 109 of 111 specimens studied (98%), the motorfascicular group of. the ulnar nerve was located at theulnar dorsal or straight dorsal position at the wrist andthe distal forearm. Specifically, in 77 specimens (69%),

870 Chow et al.

The Journal ofHAND SURGERY

ULNAR

Q 20 mm DORSAL

21.5 mmDORSAL

ULNAR

i00

mm DORSAL

ULNAR

the motor fascicular group was located at the ulnardorsal position (Figs. 1 and 2). In 32 specimens (29%),it was located at the straight dorsal position. In twospecimens (2%), it Was located at the radial dorsal po-sition.

The motor fascicular group of the uinar nerve can

..... " "~"’ : :’"’J;~ " -;’-:DORSAL ....70.,., . DORSAL ,:,-:! "~;, ~:-’ ! ,~o ~ . : ¯

Fig. 3, A-E. Diagra~atic mappings of ~e fascicul~ groups of the left uln~ nerve at represen~tivelevels The indicated level of ~e sections is in reference to the dist~ce proximal to the radialstyloid. Key: Red, motor fascicul~ group; Blue, senso~ Nscicul~ groups.

be iden~ed as a distinct anatomic entity up to 90 mmproximN from the level of the radial styloid. In the

distal ~ird of &e fore~, the motor Nscicul~ groupconsti~tes 30% to 35% of &e total Nscicul~ cross-sectionN ~ea of the uln~ nerve.

Diag~matic mappings of the fascicul~ groups of

Vol. 10A, No. 6, Part 1November 1985 Surgical significance of motor fascicular group 871

20

90

115

SSM

O.

DC

Fig. 4. Diagrarranatic schema of the fascicular groups of theulnar nerve at the wrist and forearm, Key: Red~ motor: Blue.sensory; M and S, motor and sensory fascicular groups fromthe hand; DC, dorsal cutaneous branch.

the ulnar nerve at representative levels of the wrist andforearm are shown in Fig. 3. A schema of the fasciculargroups of the ulnar nerve in the forearm is diagram-matically illustrated in Fig. 4. Note that the motor fas-cicular group from the intrinsic muscles of the handcan be readily identified up to 90 mm proximal to theradial styloid process, whereas the two sensory groupsfrom the fingers merge with each other at the 50 wanlevel. The sensory fascicular group that gives rise tothe dorsal cutaneous branch can be traced to the 250mm level.

Fig. 5. Sunderland’s diagrammatic model of the funicularplexus of the proximal musculocutaneous nerve.

DiscussionFor many years, false interpreiation and unfounded

extrapolation of Sunderland’s diagrammatic model ofthe funicular plexus of the proximal portion of the mus-culocutaneous nerve2, 3 have been made (Fig. 5). Manyclinicians referred to this diagram to claim futility inthe precise realignment of lacerated peripheral nerves.In 1945, Sunderland4 pointed out that despite the chang-ing plexiform character of the individual fascicles, thefascicular groups from the terminal branches pursue alocalized course in the nerve for considerable distancesabove the site of branching. This observation on thebundle groups (fascicular groups) has been generallyneglected. The diagrammatic drawing of the distal me-dian nerve in the article by Jabaley et al.5 illustrated

872 Chow et al.The Journal of

HAND SURGERY

Fig. 6. Diagrammatic drawing of Jabaley et al. of the fas-cicular groups of the distal median nerve.

the concept of group fascicular arrangement (Fig. 6).Our schema of the ulnar nerve (Fig. 4) was composedby averaging the anatomic data based on the study of111 specimens of the upper extremity performed at theUniformed Services University of Health Sciences. It ...agrees with Sunderland’s early work in Australia andagain shows the group arrangement of the fascicles at 1.

the distal portion of the major peripheral nerves.Sunderland reported that the fascicular pattern is con-

tinual, ly modified along the entire length of each nerveby the repeated division, anastomosis, and migrationof the fascicles, as Well as that crossing over betweenindividual fascicles occurring at distances of less than2.5 mm.4 However, he also observed that the fasciclesarrange themselves in groups and that this intraneuralfascicular group arrangement is specifically well de-fined at the distal portion of the peripheral nerves. Thefollowing observations were noted in our study of 111anatomic specimens. In the ulnar nerve at the wrist andthe distal forearm, the fascicular plexus formation ismainly limited within each of the fascicular groups,whereas the fascicular groups remain as separate entitiesfor several centimeters. Specifically, the motor fascic-ular group can be identified up to 90 mm proximal tothe radial styloid (Fig. 4). Furthermore, the fasciculargroups are surrounded by and separated from one an-

other by the intraneural epineurium. This provides theanatomic basis for the techniques of group fascicularrepair and nerve grafting.6-s

We believe that the relatively constant location of themotor fascicular group of the distal ulnar nerve hasimportant clinical significance. Most lacerations of themajor peripheral nerves of the upper extremity are atthe distal forearm or the wrist. In the surgical repair ofacute lacerations of the ulnar nerve at these levels, oneshould direct special attention to the correct identifi-cation, matching, and alignment of the motor fasciculargroup to enhance reinnervation of the intrinsic musclesof the hand. The fascicular groups of the ulnar nerveat the distal portion of the forearm may be readily iden-tified under the operating microscope.

In patients with significant segmental loss of periph-eral nerve with a polyfascicular group arrangement,nerve grafts (inteffascicular nerve grafting) are used bridge the gap between the corresponding fasciculargroups by means of the operating microscope.7’ s Thismethod of grafting, as described by Millesi, s is specif-ically applicable to the reconstruction of the motor fas-cicular group of the ulnar nerve at the wrist and distalforearm.

The principal author is indebted to Sir Sydney Sunderlandfor advice and encouragement during the preparation of thiswork and for proofreading the manuscript. We thank Mr.George Holborow, Mr. Gregory Holmes, Mr. Paul Niner, andMs. Ingrid Lynch for their technical assistance.

REFERENCES ..

Van Beck AL, Jacobs SC, Zook EG: Examination of pe-ripheral nerves with the scanning electron microscope.Plast Reconstr Surg 63:509-19, 1979

2. Sunderland S, Marshall RD, Swane’y WE: The intraneuraltopography of the circumflex, musculocutaneous and ob-turator nerves. Brain 32:116-29, 1959

3. Sunderland S: Nerves and nerve injuries, ed 1. London,1968, Churchill-Livingstone/

4. Sunderland S: The intraneural topography of the radial,median and ulnar nerves. Brain 68:243-98, 1945

5. Jabaley ME, Wallace WH, Heckler FR: Internal topog-raphy of major nerves of the forearm and hand: a currentview. J HAtqO SURG 5:1-18, 1980.

6. Van Beck AL, Kleinert HE: Practical micro~eurorrhaphy.Orthop Clin North Am 8:377-86, 1977

7. Millesi H, Meissl G, Berger A: The interfascicular graftingof the median and ulnar nerves. J Bone Joint Surg [Am]54:727-50, 1972

8. Millesi H: Nerve grafts--indications; techniques andprognosis. In Omer GE, Spinner M, editors: Managementof peripheral nerve problems. Philadelphia, 1980, WBSaunders Co, p 417