The vascular anatomy of the palmar arches and their variations has long intrigued anatomists. Relatively few studies have been performed in this area, 1–9 in part, attributable to the technical difficulties encountered in dissecting small vessels, and to their location deep in the palm within the muscle substance. Previous investigations have used gross dissection, 3,5,7 angiography, 2,5,8 and Doppler studies 1,2,4 in an attempt to understand the complex and fragile anatomy of this region. Since the classic work of Coleman and Anson in 1961, 3 there has been no reported work in the English language literature in which the arterial anatomy of the palmar arches in specimens retrieved postmortem was investigated. Improved techniques using arterial injection of polymer followed by chemical debridement have allowed more accurate and direct assessment of the fine arterial anatomy of the hand including the luminal diameter of the vessels. Recent advances in microsurgical techniques for reconstruction of the hand and upper extremity after trauma have necessitated better understanding of the vascular patterns and luminal diameters of the vessels. 5
The objective of the current study was to evaluate variations in the vascular patterns of the deep and superficial palmar arches and to measure the luminal diameters of the vessels constituting the palmar arches and their branches.
MATERIALS AND METHODS
Forty-five fresh limbs from cadavers were amputated at the level of the midhumerus. The brachial artery was cannulated with a 14-gauge polyethylene catheter, 5 to 8 cm proximal to the antecubital fossa. Transverse incisions were made in the distal phalanges of all digits. Ward’s red latex (Ward’s Inc.; Rochester, NY), or Batson’s compound (Polysciences, Warrington, PA) then was injected under firm manual pressure. Injection was thought to be adequate when the injected fluid was seen to flow through the digital incisions. A gauze bandage then was tied securely around the forearm proximal to the wrist to prevent backflow and the specimens were left at room temperature until hardening of the latex or Batson’s compound had occurred. After hardening of the injected material, the skin, subcutaneous tissues, and tendons were removed. The specimens were digested in concentrated potassium or sodium hydroxide until only the bony elements with their ligamentous attachments and a cast of the arterial system remained. The vascular patterns then were sketched, photographed, and measurements of vessel diameters were obtained using a vernier caliper.
RESULTS
Superficial Palmar Arch
The superficial palmar arch is most easily classified into two categories: complete or incomplete. Jaschtschinski 7 first subdivided the anatomic variants into these two groups in 1897. This classification system still is in use today and provides the simplest understanding of the anatomic distribution of the arches. An arch is considered to be complete if an anastomosis is found between the vessels constituting it. An incomplete arch has an absence of a communication or anastomosis between the vessels constituting the arch.
Group I: Complete Arch
A complete arch was found in 38 of 45 specimens studied (84.4%).
The complete superficial arches divided into five groups or variants: Type A: The radioulnar arch is formed by anastomosis between the superficial volar branch of the radial artery and the continuation of the ulnar artery (Fig 1A). This is the variant most commonly described in anatomic texts. This type was found in 35.5% of specimens; Type B: The superficial arch is formed by a continuation of the ulnar artery with formation of common digital vessels to the thumb and index web space (Fig 1B). This type of variant was encountered in 31.1% of specimens; Type C: The median and ulnar arteries combine to form the superficial arch without a contribution from the radial artery (Fig 1C). This variant was seen in 13.3% of specimens; Type D: This type is characterized by all three vessels, (radial, median, and ulnar), contributing to the formation of the superficial arch (Fig 1D). This variant was found in one of 29 specimens (2.2%); and Type E: A branch from the deep palmar arch communicates with an ulnar artery initiated superficial arch (Fig 1E). This variation was seen in 2.2% of specimens.
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Fig 1A–G.:
Complete superficial palmar arches were seen in 84.4% of specimens. (A) In Type A, the superficial arch is formed by anastomosis between the superficial volar branch of the radial artery and the ulnar artery. (B) Type B is formed entirely of the ulnar artery. (C) Type C is formed by anastomosis between the ulnar artery and median artery. (D) Type D is formed by anastomosis between contributions from the radial, ulnar, and median arteries. (E) In Type E, a branch from the deep palmar arch communicates with an ulnar artery initiated superficial arch. Incomplete superficial arches were seen in 15.5% of specimens. (F) In Type F, the ulnar artery forms the superficial arch but does not contribute to the blood supply to the thumb and index finger. (G) In Type G, radial and ulnar arteries contribute to the superficial arch but no anastomosis is present.
There were no specimens that had complete absence of the superficial arch. The volar interosseous artery also did not contribute to the formation of the superficial arch in any specimen.
Group II: Incomplete Arch
An incomplete arch was defined as the absence of an anastomosis between contributing vessels, or when the ulnar artery fails to reach the thumb-first dorsal web space. Seven specimens (15.5%) had an incomplete arch. These can be additionally divided into two groups or patterns: Type F: In this subgroup, the ulnar artery comprises the entire superficial arch but does not contribute to the arterial supply to the thumb and index fingers. This was the most commonly encountered variety of incomplete arch, being seen in 11.1% of specimens (Fig 1F); Type G: In this type, the superficial volar branch of the radial artery and the ulnar artery contribute to the blood supply of the fingers and palm; however, no anastomosis is present between them. This type was seen in 4.4% of specimens (Fig 1G).
There were no specimens that had complete absence of the superficial arch. The volar interosseous artery also did not contribute to the formation of the superficial arch in any specimen.
Branches of the Superficial Palmar Arch
A vessel arising from the dorsal branch of the radial artery and supplying the deep ulnar border of the thumb and a volar metacarpal branch to the radial index finger was constant in all specimens. A branch from the superficial ulnar artery to the ulnar border of the fifth finger also was constant.
The branches of the superficial arch are present in two recurrent patterns. In the first pattern, three common digital arteries supply the second, third, and fourth web spaces (17%). This is the more commonly described configuration. In the second variant, a final termination of the superficial ulnar artery provides a vascular supply to the radial border of the index and ulnar aspect of the thumb in addition to the common digital arteries described above. This was the more common pattern, being seen in 83% of specimens.
An inverse ratio was found between the diameters of the common volar digital arteries and those of the corresponding volar metacarpal arteries.
Deep Palmar Arches
Less variability is seen in the deep palmar arch than the superficial arch. The deep arch is formed by the passage of the deep branch of the radial artery from dorsal to deep volar through the two heads of the first dorsal interosseous muscle. The arch then follows a curve along the bases of the metacarpal bones. This deep arch then may anastomose with one or both deep volar branches of the ulnar artery. 8 In the current series, at least one of the deep volar branches (superior or inferior) was present in all specimens: therefore, all specimens had a complete deep arch.
The deep arch can be divided into three categories: Type A: In the first group, and most common, the deep palmar arch is formed by the anastomosis between the deep volar branch of the radial artery and the inferior deep branch of the ulnar artery. This was the most common pattern, seen in 44.4% of specimens (Fig 2A); Type B: The deep arch is created by an anastomosis between the deep volar branch of the radial artery and the superior deep branch of the ulnar artery. This variant was present in 33.4% of specimens (Fig 2B). and Type C: In this type, the deep arch is formed by the anastomosis of both deep branches of the ulnar artery with the deep volar branch of the radial artery. This variant was seen in 20% of specimens (Fig 2C).
Fig 2A–C.:
The deep volar arches are shown. (A) Type A is formed by anastomosis between the deep volar branch of the radial artery and the inferior deep branch of the ulnar artery. (B) Type B is formed by anastomosis between the deep volar branch of the radial artery and the superior deep branch of the ulnar artery. (C) Type C is formed by anastomosis between the deep volar branch of the radial artery with both deep branches of the ulnar artery.
As in the previous studies, a reciprocal relationship was found between the two arches, and the common volar digital arteries and the volar metacarpal arteries. When one is developed and prominent, the other is correspondingly less developed.
Dorsal Carpal Rete
An extreme amount of variability from specimen to specimen was seen in the dorsal carpal rete. It is comprised of numerous small, thin vessels (0.3–0.5 mm). The most consistent finding was the presence of one dorsal radial carpal branch approximately 10 to 15 mm distal to the radial styloid. This was found in 88% of specimens.
Vessel Diameters
After classification of vascular patterns of the palmar arches and their branches, measurements then were made of the luminal diameter of the vessels using a vernier caliper. The average vessel diameters are shown in Table 1 and Figure 3.
TABLE 1: Vessel Lumen Diameters
Fig 3.:
The average vessel lumen diameters are shown.
Numerous anastomosing vessels were observed between the arches. They did not form a specific pattern, however. These anastomosing branches between the deep and superficial arches measured from .3 mm to .5 mm on average.
DISCUSSION
Evaluation of the actual anatomy of the hand is difficult because of the complexity of the anatomy and the many small connecting branches. Doppler studies 1,2,4,8,9 are limited, because they only can effectively evaluate the superficial palmar arch. Angiographic studies 2,5,8 have been performed and allow visualization of the deep and superficial arches; however, they do not allow accurate assessment of the numerous small connecting vessels. In addition, unquantitated and unpredictable degrees of vasospasm and reactive vasodilatation secondary to the stress of dye injection make determination of vessel diameter unreliable. It has been suggested that angiography be performed only in the presence of brachial plexus anesthesia to allow for differentiation of organic vascular abnormalities from spastic ones. 8 In no previous study has the intraluminal diameters of the vessels been measured directly.
The results of the current study are in accordance with those previously published. 1,3,6,8,10 Some small differences are seen in the frequency of anastomotic patterns found in the current study when compared with previous studies. This may be a reflection of the relatively small sample size (the sample in the current study was only 45 specimens), or a direct result of the techniques used. Injection followed by chemical debridement has a higher probability of preserving the fine arterial anatomy than gross dissection. It also allows for direct visualization and measurement of the smaller branches that are poorly visualized at best with angiography. Therefore, injection followed by chemical debridement may allow a more accurate representation of the true anatomic relationships. This could account for the differences found in the current study, such as the increased prevalence of the median artery in the formation of the superficial arch than in previous studies. 3
The technique used allowed direct visualization of the arterial patterns and direct measurement of the luminal diameter of the vessels. The importance of a thorough understanding of the vascular anatomy of the hand has been necessitated by the improvement in microsurgical techniques used in posttraumatic and congenital hand reconstructive surgery and in general reconstructive procedures. Vessels of the superficial and deep arches have been found to be of sufficient size to allow microvascular repair, although repair of the communicating branches, the dorsal carpal rete, and its branches, probably is not feasible because of their small size.
References
1. Al-turk M, Metcalf WK: A study of the superficial palmar arteries using the doppler ultrasonic flowmeter. J Anat 138:27–32, 1984.
2. Balas P, Katsongiannis A, Katsiotis P, et al: Comparative study of evaluation of digital arterial circulation by doppler ultrasonic tracing and hand arteriography. J Cardiovasc Surg 21:455–462, 1980.
3. Coleman SS, Anson BJ: Arterial patterns in the hand based upon a study of 650 specimens. Surg Gynecol Obstet 113:409–424, 1961.
4. Doscher W, Viswanathan B, Stein T, et al: Hemodynamic assessment of the circulation in 200 normal hands. Ann Surg 198:776–779, 1983.
5. Edwards EA: Organization of the small arteries of the hand and digits. Am J Surg 99:837–846, 1960.
6. Gould JS: Microsurgical reconstruction of the hand. Microsurgery 10:1747–1753, 1987.
7. Jaschtschinski SN: Morphologie und topographie des arcus volaris sublimis und profundus. Anat Hefte 7:163–188, 1897.
8. Karlsson S, Niechajev IA: Arterial anatomy of the upper extremity. Acta Radiol Diag 23:115–121, 1982.
9. Little JM, Zylstra PL, West J, et al: Circulatory patterns in the normal hand. Br J Surg 60:652–655, 1973.
10. Tandler J: Zur anatomie der arterien der hand. Anat Hefte 7:263–282, 1897.
Section Description
Michael J. Botte, MD; and James R. Doyle, MD Guest Editors
