The blood supply of the lumbrical muscles

THE BLOOD

SUPPLY OF THE LUMBRICAL

MUSCLES

A. ZBRODOWSKI, E. MARIETHOZ, M. BEDNARKIEWICZ and S. GAJISIN

From the Division of Anatomy, Department of Morphology, University Medical Centre, Geneva, Switzerland The blood supply of the lumbrical muscles was studied in 100 upper extremities from fresh human cadavers. Layer by layer dissection revealed the existence of different types of vascularity for the four muscles. The injection of coloured latex or Indian ink solution with gelatin showed the complex arterial network of these muscles together with their various sources of blood supply. Four separate sources of blood supply for each of the muscles were found: the superficial palmar arch (SPA), the common palmar digital artery, the deep palmar arch (DPA) and the dorsal digital artery. It was established that there were no anastomoses between the blood vessels of the tendons of the flexor digitorum profundus muscle and those of the lumbrical muscles. Considerable differences were observed in the details of the blood supply of the individual lumbrical muscles.

Journal of Hand Surgery (British and European Volume, 1998) 23B." 3." 384-388 The lumbrical muscles constitute an important part of the intrinsic musculature of the hand and play an important role in its normal function. They are four in number and arise from the tendons of the flexor digitorum profundus: the first and second from the radial side of the radial two fingers, and the third and the fourth from the adjoining sides of the two ulnar fingers. They are attached to the lateral margin of the dorsal digital expansion of the extensor apparatus of the finger. The patterns of origin and insertions of the lumbrical muscles have many differences. Variations in the attachment of the lumbricals are very common, and have been treated extensively by Basu and Hazary (1960), Bossy and Gondy (1961), Eyler and Markee (1954), Fahrer (1975, 1979), Russel and Sunderland (1938), Sunderland (1945), and Winkler (1969). Numerous functions have been attributed to these muscles. The lumbrical muscles certainly join forces with the interossei muscles in performing the fine coordinated movements in the fingers. They participate in the flexion and stabilization of the metacarpophalangeal joint and in the extension of the interphalangeal joint. They can be considered as active participants in flexion and extension of the fingers and as important regulators of the action between the flexor and extensor muscles. The functional aspects of the intrinsic muscles of the hand were described by Braithwaite et al (1948), Eyler and Markee (1954), Kaplan (1968), Mehta and Gardner (1961), Parkes (1970), Stack (1962, 1970), and Valentin (1980). Several authors have described the variations of the innervation of the different lumbrical muscles in the hand (Bonnel, 1983; Fahrer, 1979; Mehta and Gardner, 1961; Sunderland, 1945; Winkler, 1969). Textbooks of gross anatomy and other relevant medical literature do not adequately explain the blood supply of these muscles. A few authors have concluded that these muscles may be supplied by the superficial and deep palmar arches (Gajisin and Zbrodowski, 1993; Miyaji et al, 1978; Valentin, 1980; Zbrodowski and Gajisin, 1991). The present study was undertaken to provide anatomical information about the detail of the blood supply of the lumbrical muscles in the human hand.

MATERIAL AND METHODS

This study was carried out on 60 cadavers (25 male and 35 female) in an age range of 50 to 80 years. Only 100 upper extremities were selected for this study (in 44 cadavers both the left and right hands were used and in the 16 remaining cadavers only one hand was available). The material was divided in three groups: • The first group of specimens was rinsed with heparin solution (25000 iu in 1000 ml distilled water) for 6 hours. Following the rinsing, the specimens were injected with a mixture of glycerine, phenol, alcohol and formalin. Twenty-four hours later another solution of latex mixed with Indian ink was injected. • The second group of specimens was injected directly with the solution of Indian ink and gelatin and then stored for 2 weeks in 5% formalin. • The third group was injected with coloured latex and stored in 10% formalin for at least 2 weeks. All of the injections were made through the brachial artery. The specimens injected with latex were dehydrated in a graded series of alcohol and transferred to a Spalteholz solution for clarification. After 6 months of transelarification, the internal arterial distribution of the lumbrical muscles was visualized. A Bausch and Lomb (Rochester, NY, USA) Stereo Zoom dissecting microscope was used fbr dissection and a Wild (Heerbrugg, Switzerland) M 400 Macrophot for photography. The hand was dissected in layers from both the palmar and dorsal sides. A palmar midline incision was made through the skin and palmar aponeurosis of the hand and middle finger. The synovial sheath of the carpal tunnel was opened longitudinally and the hand was dissected layer by layer. The main arteries were found and their branches followed from deep within towards the skin, thus following the direction of the flow. The arterial branches for skin, fascia and others structures were cut off 1 cm from the superficial palmar arch and common palmar digital arteries. 384

385

BLOOD SUPPLY OF LUMBRICAL MUSCLES

Then the hand was turned over in order to dissect the dorsal side. A dorsal midline incision was made through the skin and fascias to reach each metacarpal bone which was then excised subperiosteally. The deep palmar arch and the flexor digitorum profundus muscle were left in place. The muscular arteries were dissected from the dorsal and palmar sides and special care was taken with the arteries o f the lumbrical muscles. The arteries and their arborizations were traced at a magnification of 10 x. RESULTS The middle palmar space of the hand is bounded by the thenar and hypothenar eminence on each side. The flexor tendons pass through the middle palmar space on their way to the fingers. The lumbrical muscles, four in number, arise from the tendons of the flexor digitorum profundus and attach to the dorsal digital expansion. They lie between the metacarpal bones and the flexor digitorum superficialis muscle. This position in the middle palmar space between the common flexor sheath and the digital fibrous sheaths is very advantageous for the vascularization of these muscles. The present investigation shows that the lumbricals by their position in the hollow of the hand received their blood supply from four different sources: the superficial palmar arch; the common digital arteries; the deep palmar arch and palmar metacarpal arteries; and the dorsal digital arteries

Branches of the superficial palmar arch (SPA) The SPA sends off small branches to all the lumbrical muscles. These arterial branches are known as indirect

Fig 1 Flexor tendons with lumbrical muscles and arteries of the hand. 1. Flexor digitorum superficialismuscle, 2. Flexor digitorum profundus muscle, 3. First lumbrical muscle, 4. Second lumbrical muscle, 5. Third lumbricalmuscle, 6. Fourth lumbrical muscle, 7. Superficialpalmar arch (SPA), 8. Deep palmar arch (DPA), 9. Common palmar digital artery, 10. Palmar metacarpal artery, 11. Muscular branches for lumbricals, 12. Tendon branches for the flexormuscles.

muscular branches. They have a common trunk and divide in two branches one of which penetrates the lumbrical muscle and the other supplies the flexor tendon (Fig 1). The muscular branch usually enters at the palmar surface of the muscle by a clearly visible vascular hilum. We observed from three to five small branches which penetrated the muscle at the level of origin of the lumbricals from the tendons of the flexor profundus muscle (Fig 2). In a large number of cadavers we observed frequent variations of the SPA with regard to the origin of its constituent arteries, size and site of anastomoses. Independent of this variation, the SPA constantly participates in the vascularity of the lumbrical muscles.

Branches from the common digital arteries From the convex side of the SPA arise common palmar digital arteries. They participate in the blood supply of the different structures in the palm of the hand and also give direct branches to the lumbrical muscles (Fig 3). These arteries are short and penetrate the palmar surface of the muscle near the origin of the digital sheath of the flexors. We observed from one to two arterial branches which penetrated into the hilum of the muscle, but sometimes these arteries divided into four or five branches.

Branches from the deep palmar arch (DPA) and palmar metacarpal arteries The origin of the DPA and its topography is more constant than the SPA. It is formed by anastomosis of the deep branches of the radial and ulnar arteries (Fig 4). In its concavity arise palmar metacarpal arteries which give one or two small direct branches for the lumbricals (Fig 5). In the palm, the lumbrical muscles are surrounded by loose paratenon. In this paratenon the branches of the palmar digital arteries reach the dorsal surface of some of the lumbrical muscles. In this situation the deep palmar arch gives only a few muscular branches. The

Fig 2 Tendinealand lumbrical branches of SPA. (Keyas for Fig 1).

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THE J O U R N A L OF H A N D SURGERY VOL. 23B No. 3 JUNE 1998

Fig 3 Blood supply of the first lumbrical muscle. (Key as for Fig 1).

Fig 4

arterial branches which arise from the DPA or from the palmar metacarpal arteries usually enter the lumbricals from the dorsal aspect of the muscle, and form anastomoses with the intramuscular network.

tion than the others, its arterial network was smaller. A collateral circulation was found in a segment of the muscle and also between the interfascicular anastomoses.

Dorsal view of DPA and its branches. (Key as for Fig 1).

DISCUSSION

Branches from the dorsal digital arteries Insertion of the lumbricals is by a small tendon which reaches the dorsal digital expansion of the extensor digit o r u m muscle. In this region we observed the vascular network of the arterial branches formed by three branches from the dorsal digital artery, the dorsal branch of the digito-palmar arch and the dorsal branch of the proper palmar digital artery. They provide an additional source of blood supply to the lumbrical muscles, and are formed by three to six arterial branches (Figs 6 and 7). Variations in the vascularization of the lumbricals are common, particularly the third lumbrical muscle which showed frequent changes. Although the first lumbrical muscle was found to have more sources of vasculariza-

The blood supply of the lumbrical muscle is independent of the development of the radial and ulnar arteries and the topography of the superficial palmar arch. The arteries from the four sources participate in the vascularization of each lumbrical muscle from the palmar and dorsal surfaces. Between them they form anastomoses which give rise to smaller branches which penetrate the intrafascicular space of the muscle. The main blood supply of these muscles is the SPA (Figs 1, 2 and 3). This source of muscular blood supply is richer than the others. Our study clearly showed that there were no anastomoses between the networks supplying the lumbrical muscles and the tendons of the flexor profundus muscle (Figs 2 and 6). The DPA gives only a

Fig 5 Deep surface of the lumbrical supply by the branches of the DPA. (Key as for Fig 1).

Fig 6 Differentsources of the blood supply for isolated lumbrical muscles. (Key as for Fig 1).

BLOOD SUPPLY OF LUMBRICAL MUSCLES

Fig 7

387

Blood supply of the dorsal digital expansion of the extensors. l. Dorsal digital expansion, 2. Palmar interosseous muscle, 3. Lumbrical muscle, 4. C o m m o n palmar digital artery, 5. Proper palmar digital artery, 6. Digito-palmar arch, 7. Dorsal branch of the digito-palmar arch, 8. Dorsal branch of the proper palmar digital artery, 9. Dorsal metacarpal artery, 10. Dorsal digital artery, 11. Tendineal branches for the dorsal digital expansion.

few muscular branches and never to all muscles in the same hand (Figs 4 and 5). During dissection there were considerable variations in the topography of the principal arterial branches in the different lumbrical muscles, both between different persons and between right and left hands. The type of blood supply varied in number of branches and in size from one muscle to other. The organization of the arterial vessels in the hand should not be considered in the classical anatomical sense, but rather as a system supplying a specific territory. This kind of arrangement can be observed in the blood supply of the dorsal digital expansion of the extensor muscle where the tendons of the lumbrical muscles are inserted. Each of the lumbrical muscles has a segmental blood supply. The proximal third of the muscle is supplied by one or two branches from the SPA. The middle third of the muscle is supplied by direct vessels from the common digital artery, two or three branches of which may enter the belly of the lumbrical muscle. The distal third of the muscle is supplie& by branches from the dorsal metacarpal arteries (Fig 7). At the region of insertion, the tendon of the muscle is supplied by the arterial network formed by the dorsal branches of the digito-palmar arch, common digital artery and dorsal digital artery (Fig 8).

Acknowledgements We are indebted to Dr E.W. Watson for his competent assistance in editing and translating this paper. We also wish to thank both Mrs F. Hellal for preparing the manuscript and Mr D. Semedo for his technical assistance.

Fig 8

Schematic drawing of the dorsal digital expansion of the extensors. (Key as for Fig 7).

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T H E J O U R N A L OF H A N D SURGERY VOL. 23B No. 3 JUNE 1998 Received: 1 August 1997 Accepted after revision: 19 November 1997 A. ZbrodowskiMD, Divisiond'Anatomie,Centre M~dical Universitaire. 1 rue Michel-Servet, Chl211 Geu6ve4, Switzerland. © 1998The British Societyfor Surgery of the Hand