B. S. Mitchell, Centre for Learning Anatomical Sciences, Medical Education Division, School of Medicine, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, Southampton SO16 7PX, UK. E-mail: B.S.Mitchell@soton.ac.uk
The normal arterial supply to the human hand is via the ulnar and radial arteries which unite mid-palm to form a complete arch called the superficial palmar arch (SPA). From the SPA blood vessels pass anteriorly to supply the thumb and digits, and deeply to complete the deep palmar arch. Previous reports have documented anomalies of the SPA formation, and this may change the normal blood distribution to the thumb and the digits. There have also been reports of the absence of the palmaris longus tendon. A total of 47 embalmed cadaveric hands (some paired, some single) were dissected and the presence of an anomalous SPA was more frequently observed when the palmaris longus tendon was absent. This may be significant when considering the suitability of patients for hand surgery which involves interruption to the vascular supply to the hand, e.g. harvesting upper limb vessels for coronary artery grafting. The current techniques for assessing the vascular supply to the hand (Allens test and/or Doppler ultrasounding) are unreliable. Demonstration of a palmaris longus tendon in the living arm is easy and the use of this in combination with the other techniques may improve overall reliability.
The normal arterial blood supply to the human hand is well documented (Rosse & Gaddum-Rosse, 1997; Agur & Lee, 1999; Moore & Dalley, 1999; Sinnatamby, 1999; Snell, 2000). The vascular supply to the hand and digits via the superficial palmar arch (SPA) is known to be variable (Al-Turk & Metcalf, 1984; Ikeda et al. 1988; Onderoglu et al. 1997; Bianchi, 2001; Gellman et al. 2001). Indeed, although the classical pattern of the SPA occurs infrequently (Doscher et al. 1985; Gellman et al. 2001), the anastomoses between the radial and ulnar arteries are sufficient to supply the hands and all the digits; hence harvesting a radial artery, for example, should not compromise the arterial supply to the distal hand. Ruengsakulrach et al. (2001) comment that even though a typical SPA was present in only 5/50 hands there were nevertheless major arterial communications between the radial and ulnar arteries in 50/50 cadaveric hands they examined. Ultrasound studies (Doscher et al. 1983, 1985) indicated that following occlusion of the radial artery there was an increase in blood flow within the SPA in all but 11% of subjects examined, indicating the communications facilitated by the SPA. Gellman et al. (2001) describe how even though the ulnar artery is the dominant artery forming the SPA in 5/45 cadaveric hands they dissected there were no branches from the arch to the thumb and index finger. The absence of a palmaris longus tendon (Thompson et al. 2001) has also been documented. However, the association of the absence of a palmaris longus tendon and the presence of an anomalous SPA have not previously been reported.
The absence of a palmaris longus tendon may therefore be a predictor of the pattern of the SPA. This may have relevance in identifying suitable patients for surgery involving the vascular supply to the hand especially harvesting upper limb vessels for coronary artery grafting, and exploratory (Parks et al. 1978; Richards et al. 1993) or reconstructive hand surgery (Pierer et al. 1992; Khan et al. 1998). The current methods of assessment of blood supply to the hand, i.e. Allens test, Doppler ultrasounding (Al-Turk & Metcalf, 1984) and modified Allens test (Starnes et al. 1999), have been shown to be unreliable. Since the presence of a palmaris longus tendon is easily identifiable in the living arm without using invasive techniques, in conjunction with existing tests, it may improve overall reliability in the selection of suitable patients for hand surgery.
Materials and methods
A total of 47 embalmed cadaver hands were examined. The cadavers were embalmed using the normal embalming method and fluid used at the Centre for Learning Anatomical Sciences, School of Medicine, University of Southampton (O’Sullivan & Mitchell, 1993). Prior to embalming, cadaver hands are routinely fixed with the fingers extended which facilitates subsequent dissection. The hands were dissected in the following way. The skin covering the flexor surface of the wrist and palm to the base of the digits was removed. The presence or absence of palmaris longus was recorded and the ulnar and radial arteries were identified at the wrist. The palmar aponeurosis was removed to reveal the SPA and this was clearly demonstrated by dissection of the surrounding adipose tissue and removal of the branches of the median and ulnar nerves from the palm of the hand. The common palmar arteries were dissected to the base of the digits. The presence of an anomalous arch was recorded diagrammatically and digitally (Olympus digital camera C-1400XL). Statistical analysis was performed using the chi-squared test.
Table 1 shows the results of the investigation, while Fig. 1 shows a typical anomalous SPA arrangement.
Table 1. Results of the investigation
¸= present; ˚= absent.
% of hands examined
In 22/25 hands with anomalous superficial palmar arches there was no palmaris longus tendon, whereas in only 3/22 hands with anomalous palmar arches was a palmaris longus tendon present. This is a highly significant difference (χ2 = 26.41, P= 0.0005), indicating a significant association between the two anatomical features.
Our findings indicate that if the palmaris longus tendon was absent then in 47% of the hands it was associated with an abnormal SPA. In the remaining 40% of the hands we examined, where the palmaris longus tendon was present, this was associated with the presence of a normal SPA. The observations of the 6.5% of hands where an anomalous SPA was found associated with a palmaris longus tendon, and the 6.5% of hands where a normal SPA was found with no palmaris longus tendon do not significantly weaken the overall predictive power of this simple method. Indeed, in statistical analyses of the total number of hands examined in the present study there was a highly significant difference between the proportion of hands with an anomalous arch and no palmaris longus tendon compared to the proportion with anomalous arches and with a palmaris longus tendon. This simple test offers a significant improvement when used in conjunction with the current clinical techniques.
We thank J. R. Skidmore for helpful comments on the manuscript and P. D. Adams for assistance with digital photography.