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Axillary arch accompanying variations of the brachial plexus
Journal of Plastic, Reconstructive & Aesthetic Surgery (2009) 62, e180ee181
CORRESPONDENCE AND COMMUNICATION
Axillary arch accompanying variations of the brachial plexus Case report The axillary arch, as a common muscular variation within the axilla, is generally found in the form of a thin muscular slip that extends between the latissimus dorsi muscle and the pectoralis major muscle.1 An axillary arch with variations of the brachial plexus was observed in the left axillary region of the cadaver of an approximately 50-year-old Korean man during educational dissection in our college. The muscle extended from the lateral edge of the latissimus dorsi muscle across the axillary sheath into the tendon of insertion of the lesser tubercle of the humerus, thus identifying itself as the ‘axillary arch of Langer’ (Figure 1a). It was 6.5 cm in length and 1 cm in width. The blood supply and nerve innervation of this muscle came from the subscapular artery and the thoracodorsal nerve, respectively. The axillary arch was intertwined with the neurovascular bundle in the axilla (Figure 1b). It perforated the posterior cord inferior to the third part of the axillary artery. The lower subscapular and axillary nerves arose from the lower part of the posterior cord. The thoracodorsal nerve arose from the upper and lower parts of the posterior cord. Therefore, the thoracodorsal and
axillary nerves, the subscapular artery and the lower part of the posterior cord were observed dorsal to the axillary arch. The median nerve was formed by the fusion of three roots: two from the lateral cord and one from the medial cord (Figure 1b). The lateral cord was divided into three branches just next to the thoracoacromial artery: the musculocutaneous nerve, the normal lateral cord and the variant lateral cord. The normal lateral cord continued for 1.5 cm and then joined the median cord to form the median nerve. The variant lateral cord joined the medial nerve 15 cm distal to the union of the medial and normal lateral roots of the median nerve. From here, the course and the innervations of the musculocutaneous and median nerves were normal.
Discussion The axillary arch is not a rare variation, and several cases have been reported previously.1 We have presented the first case of the axillary arch that perforated the posterior cord and coexisted with variation of the median nerve. It is clinically important for surgeons performing axillary surgery, especially breast reconstruction using the latissimus dorsi myocutaneous flap, because of its close relationship to neurovascular variations.2 Though each variant occurs only in a certain percentage of individuals, the development of the axillary arch may have influenced the
Figure 1 Photograph (a) and schematic drawing (b) of the left axilla showing the axillary arch (*) and the variations of the brachial plexus. AA, axillary artery; TAA, thoracoacromial artery; SSA, subscapular artery; MCN, musculocutaneus nerve; VLC, variant lateral cord; MN, median nerve; UN, ulnar nerve; MCF, medial cutaneous nerve of forearm; PC, posterior cord; LSN, lower scapular nerve; AN, axillary nerve; RN, radial nerve; TDN, thoracodorsal nerve; LDM, latissimus dorsi muscle. 1748-6815/$ - see front matter ª 2008 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.bjps.2008.08.043
Correspondence and communication formation of the brachial plexus, considering the embryological aspect. Variations of the brachial plexus can be accompanied occasionally by an abnormally placed artery.3 Similarly, the brachial plexus could also be modified by the presence of the axillary arch which can decrease the available space required for normal development and it could explain the coexistence of such a neuromuscular variation.4 The presence of the axillary arch significantly increases the risk of iatrogenic damage to the axillary vessels and brachial plexus.5 If accompanying variations are also present, possible damage to the axillary neurovascular bundle during surgery increases. Combined variations of the axillary arch and the brachial plexus, such as those in our case, have not been reported previously. Although the hypothesis that the axillary arch contributes to forming the variation in the neurovascular structures has not been clearly proved, surgeons should be aware not only of the axillary arch but also of the related variations.
Acknowledgement This work was supported by grant No. R13-2002-028-03002-0 from the Basic Research Program of KOSEF for medical research centers.
References 1. Me ´rida-Velasco JR, Rodrı´guez Va ´zquez JF, Me ´rida Velasco JA, et al. Axillary arch: potential cause of neurovascular compression syndrome. Clin Anat 2003;16:514e9.
e181 2. McWhirter D, Malyon A. The axillary arch: a rare but recognised variation in axillary anatomy. J Plast Reconstr Aesthet Surg 2008;61:1124e6. 3. Miller RA. Comparative studies upon the morphology and distribution of the brachial plexus. Am J Anat 1934;54:143e7. 4. Sachatello CR. The axillopectoral muscle (Langer´s axillary arch): A cause of axillary vein obstruction. Surgery 1977;81:610e2. 5. Daniels IR, della Rovere GQ. The axillary arch of Langer - the most common muscular variation in the axilla. Breast Cancer Res Treat 2000;59:77e80.
Jae-Ho Lee In-Jang Choi Department of Anatomy, School of Medicine, Keimyung University, Daegu, Republic of Korea Dae-Kwang Kim Department of Anatomy, School of Medicine, Keimyung University, Daegu, Republic of Korea Institute for Medical Genetics, School of Medicine, Keimyung University, Daegu, Republic of Korea Hanvit Institute for Medical Genetics, Daegu, Republic of Korea E-mail address: [email protected]
CORRESPONDENCE AND COMMUNICATION
Axillary arch accompanying variations of the brachial plexus Case report The axillary arch, as a common muscular variation within the axilla, is generally found in the form of a thin muscular slip that extends between the latissimus dorsi muscle and the pectoralis major muscle.1 An axillary arch with variations of the brachial plexus was observed in the left axillary region of the cadaver of an approximately 50-year-old Korean man during educational dissection in our college. The muscle extended from the lateral edge of the latissimus dorsi muscle across the axillary sheath into the tendon of insertion of the lesser tubercle of the humerus, thus identifying itself as the ‘axillary arch of Langer’ (Figure 1a). It was 6.5 cm in length and 1 cm in width. The blood supply and nerve innervation of this muscle came from the subscapular artery and the thoracodorsal nerve, respectively. The axillary arch was intertwined with the neurovascular bundle in the axilla (Figure 1b). It perforated the posterior cord inferior to the third part of the axillary artery. The lower subscapular and axillary nerves arose from the lower part of the posterior cord. The thoracodorsal nerve arose from the upper and lower parts of the posterior cord. Therefore, the thoracodorsal and
axillary nerves, the subscapular artery and the lower part of the posterior cord were observed dorsal to the axillary arch. The median nerve was formed by the fusion of three roots: two from the lateral cord and one from the medial cord (Figure 1b). The lateral cord was divided into three branches just next to the thoracoacromial artery: the musculocutaneous nerve, the normal lateral cord and the variant lateral cord. The normal lateral cord continued for 1.5 cm and then joined the median cord to form the median nerve. The variant lateral cord joined the medial nerve 15 cm distal to the union of the medial and normal lateral roots of the median nerve. From here, the course and the innervations of the musculocutaneous and median nerves were normal.
Discussion The axillary arch is not a rare variation, and several cases have been reported previously.1 We have presented the first case of the axillary arch that perforated the posterior cord and coexisted with variation of the median nerve. It is clinically important for surgeons performing axillary surgery, especially breast reconstruction using the latissimus dorsi myocutaneous flap, because of its close relationship to neurovascular variations.2 Though each variant occurs only in a certain percentage of individuals, the development of the axillary arch may have influenced the
Figure 1 Photograph (a) and schematic drawing (b) of the left axilla showing the axillary arch (*) and the variations of the brachial plexus. AA, axillary artery; TAA, thoracoacromial artery; SSA, subscapular artery; MCN, musculocutaneus nerve; VLC, variant lateral cord; MN, median nerve; UN, ulnar nerve; MCF, medial cutaneous nerve of forearm; PC, posterior cord; LSN, lower scapular nerve; AN, axillary nerve; RN, radial nerve; TDN, thoracodorsal nerve; LDM, latissimus dorsi muscle. 1748-6815/$ - see front matter ª 2008 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.bjps.2008.08.043
Correspondence and communication formation of the brachial plexus, considering the embryological aspect. Variations of the brachial plexus can be accompanied occasionally by an abnormally placed artery.3 Similarly, the brachial plexus could also be modified by the presence of the axillary arch which can decrease the available space required for normal development and it could explain the coexistence of such a neuromuscular variation.4 The presence of the axillary arch significantly increases the risk of iatrogenic damage to the axillary vessels and brachial plexus.5 If accompanying variations are also present, possible damage to the axillary neurovascular bundle during surgery increases. Combined variations of the axillary arch and the brachial plexus, such as those in our case, have not been reported previously. Although the hypothesis that the axillary arch contributes to forming the variation in the neurovascular structures has not been clearly proved, surgeons should be aware not only of the axillary arch but also of the related variations.
Acknowledgement This work was supported by grant No. R13-2002-028-03002-0 from the Basic Research Program of KOSEF for medical research centers.
References 1. Me ´rida-Velasco JR, Rodrı´guez Va ´zquez JF, Me ´rida Velasco JA, et al. Axillary arch: potential cause of neurovascular compression syndrome. Clin Anat 2003;16:514e9.
e181 2. McWhirter D, Malyon A. The axillary arch: a rare but recognised variation in axillary anatomy. J Plast Reconstr Aesthet Surg 2008;61:1124e6. 3. Miller RA. Comparative studies upon the morphology and distribution of the brachial plexus. Am J Anat 1934;54:143e7. 4. Sachatello CR. The axillopectoral muscle (Langer´s axillary arch): A cause of axillary vein obstruction. Surgery 1977;81:610e2. 5. Daniels IR, della Rovere GQ. The axillary arch of Langer - the most common muscular variation in the axilla. Breast Cancer Res Treat 2000;59:77e80.
Jae-Ho Lee In-Jang Choi Department of Anatomy, School of Medicine, Keimyung University, Daegu, Republic of Korea Dae-Kwang Kim Department of Anatomy, School of Medicine, Keimyung University, Daegu, Republic of Korea Institute for Medical Genetics, School of Medicine, Keimyung University, Daegu, Republic of Korea Hanvit Institute for Medical Genetics, Daegu, Republic of Korea E-mail address: [email protected]