This anatomical study assesses the vascular supply to the radial nerve and its major branches.
An average of 2.9 arterial branches supplied the radial nerve between the distal end of the humeral groove and its terminal division, with the majority either perforating muscular branches from the triceps and brachialis muscles or branching directly off the profunda brachii artery. These findings correlate with those of Păduraru, who found between 2 to 6 collaterals emanating from the profunda brachii artery to the radial nerve in the arm [18].
A consistent vascular network was found in between the two heads of the supinator, surrounding the proximal portion of the PIN and yielding several branches to it as it traversed this region (Fig. 3). This vascular network may be involved in compression of the PIN at the level of the supinator, in a similar manner to which the recurrent radial artery acts in the proximal aspect of the radial tunnel [13]. This plexus may also be a focus of investigation during the workup of radial tunnel syndrome, using advanced ultrasonography techniques that allow visualization of lower-velocity blood flow and smaller vessels without contrast [9]. Interestingly, despite its close proximity, only a small proportion of the distal PIN’s vascular supply was found to arise from the PIA.
The SRN was regularly supplied by either muscular perforators (predominantly from the brachioradialis) or septocutaneous branches throughout its course in the forearm. These first data do not favor a vascular hypothesis for the formation of painful distal radial nerve neuromas after a sharp injury. However, this hypothesis cannot be excluded, as the diameter of septocutaneous arteries seemed smaller than the diameter of muscular branches, although not objectively measured. Additional data, especially in vivo ultrasonography, may be necessary to confirm of infirm this hypothesis and further study radial sensory branch vascularization [9].
This study adds to the scant literature assessing vascular supply to peripheral nerves – in particular, the terminal branches of the radial nerve. El-Barrany investigated and classified vascularization patterns to potential donor vascularized nerve grafts (Table 1), describing the SRN as a type 2 (receiving its blood supply from a single dominant vessel that accompanies the nerve for most of its length)[6]. The findings of this study disagree – multiple dominant vessels were noted along the length of the nerve, corresponding to type 4. The PIN similarly demonstrated multiple dominant pedicles (type 4), although a consistent continuous plexus was noted in the sub-supinator section of the nerve (type 5) [6].
Table 1
El Barrany’s classification of peripheral nerves vascularization17.
Type 1 | No dominant pedicle |
Type 2 | One dominant pedicle |
Type 3 | One dominant pedicle that divides into ascending and descending branches |
Type 4 | Multiples dominant pedicles |
Type 5 | The regional arteries give the dominant arteries that give ascending and descending branches forming a continuous artery along the external surface of the nerve |
To allow more reproducible mapping and classification of vascular supply to a peripheral nerve, we propose an alternate classification based on the origin of the arterial branches, as follows:
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Type 1: arterial branch arising from an artery
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Type 2: arterial branch arising from a muscular perforator
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Type 3: arterial branch arising from a peri-nervous vascular plexus
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Type 4: arterial branch arising from a communicating branch between two arteries
This classification is based on our findings during dissections for the current study – assessments of vascular supply to other peripheral nerves may validate its reliability and generalizability.
This study has a number of limitations. A small sample size may limit interpretation to a broader clinical population. The homogeneity of the cadavers [all obtained from European donors] did not allow investigation of ethnic variation [10]. Dissection was carried out under loupe magnification alone, allowing identification of the extrinsic vasculature of the nerves only – intraneural dissection using greater magnification will allow appreciation of internal vascularization [16, 17].
However, this study describes the arterial supply of the radial nerve and its branches, which have been poorly studied previously. In particular, it finds a consistent arterial anastamosis surrounding the proximal PIN which may contribute to radial tunnel compression. Further clinical studies should investigate the compressive capacity of this plexus, as well as the importance of the described vasculature in neurological regeneration.