Editorial
Axillary Arch: Disorientating the Axilla!
Eleni I Effraimidou*
Department of Surgery, Faculty of Medicine, Democritus University of Thrace, University Hospital of
Alexandroupolis, Greece
*Corresponding author: Eleni I Effraimidou, Department of Surgery, Faculty of Medicine, Democritus University of Thrace, University Hospital of Alexandroupolis, Greece
Published: 23 Oct, 2017
Cite this article as: Effraimidou EI. Axillary Arch:
Disorientating the Axilla!. Clin Surg.
2017; 2: 1687.
Editorial
Axilla is an anatomical region with a complex anatomy, containing the neurovascular bundle to the upper limb and its co-laterals, several critical nerves, arteries and muscles, and lymphatics. Furthermore, due to connection with the breast, axilla is the common route for metastatic involvement from breast cancer. As a result, in cases of breast cancer, the absence or presence of cancer cells in axillary lymph nodes is the most power prognostic indicator for the disease. The increasing surgical importance of the axilla region during any axillary surgery has stimulated the interest for the anatomical variations of the axilla, which have been described in textbooks of human anatomy and in those of operative surgery [1,2]. Review of the anatomical and surgical literature revealed that there are three supernumerary muscles, namely the axillary arch, the pectoralis quartus and the chondroepitrochlearis muscles, as well as the aplasia of the lower part of the pectoralis major muscle. The frequency of all these anomalous muscular variations is higher in cadaveric dissections than the one reported during surgery [3]. This lower frequency is probably due to the fact that even experienced surgeons are not familiar with the existence of AA and the other anomalous muscles. The other fact, explaining the difference in frequency, is that during surgery the region is not dissected thoroughly, as it happens in anatomical dissections. A surgeon may encounter these muscular variations when performing regional surgical procedures, such as axillary dissection and lymphadenectomy for breast cancer, lymph node biopsy, reconstruction techniques and axillary bypass operations [3,4]. Axillary Arch (AA), is the most important of these variations, and has been reported to cause difficulty during Axillary Lymphadenectomy (AL) or Lymph Node Biopsy (LNB), and also it may compress the neurovascular bundle [1,5-9].
Anatomical and Surgical Literature Review
The Axillary Arch (AA) or Langer’s axillary arch or axillopectoral muscle or pectodorsal muscle, was first described by Ramsay in 1795 and then confirmed by Langer in 1864. This supernumerary muscle is reported to have an incidence of 0.25% to 43.8% in the literature, while the reported percentage during surgery has been found to be 0.25% to 6.52% [1,3]. The typical AA extends from the anterior border of the latissimus dorci muscle to the posterior layer of the pectoralis major tendon, crossing the axilla in a relatively high frequency of 7% to 8% of population [3]. Moreover, this muscular arch shows great variability and it is described in the literature to has multiple insertions into anywhere along a line extending from the pectoralis major insertion to the coracoids process. Multiple axillary arches, as well as, a single axillary arch with multiple insertions have also been reported.
Clinical and Surgical Implications
Axillary dissection is a surgical procedure that incises the armpit (axilla) to identify, examine
and remove axillary lymph nodes. Axillary dissection is utilized to stage breast cancer (axillary
lymphadenectomy -AL, axillary nodes sampling -ANS, axillary sentinel node biopsy -SLNB), in
order to determine the necessity of further treatment [7-9].
Additionally, AL is indicated for treating persons diagnosed with operable breast cancer, who
are undergoing any type of mastectomy. During the surgical approach of the axilla, the boundaries
of the surgical field form a triangle with the serratus anterior muscle at its base and the medial
surface of the humerus, where the pectoralis major and the latissimus dorci muscles meet, at its
apex. The anatomical structures within the axillary region are expected to appear during AL [3,7-9].
Most AL includes lymph nodes from Level I and II (lateral and posterior to the pectoralis minor
muscle) [3,4,7-9]. In order to remove these nodes with minimal morbidity, the surgeon will have to
indentify several structures, which are:
• The lateral border of the pectoralis minor and major muscles
• The latissimus dorci muscle
• The axillary vein
• The long thoracic nerve
• The thoraco-dorsal nerve
• The intercostal brachial nerves
• The lateral pectoral nerve.
Two important structures must be identified and preserved: the
long thoracic nerve (or Bell’s nerve), which runs craniocaudally on the
medial wall over the serratus anterior, and the neurovascular bundle
to the latissimus dorci, which runs craniocaudally on the posterior
wall over the latissimus dorci [7-9]. This vascular bundle is particularly
important as it is the pedicle on which we base our latissimus dorci
myocutaneous flap (LD flap) during LD-breast reconstruction
technique [9]. Clinically not all of muscular anomalies are important
for axillary surgery, especially for AL. From the topographical
point of view, only the muscular bands that pass through the axilla
or change the boundaries of the surgical field may affect axillary
dissection. As it is discussed above there are three anomalous muscles
that may affect axillary dissection. In the literature there are only
few reports analyzing the complications that may arise from each
of these muscular anomalies, whereas most of them are referring to
the implications arising from AA. AA can occasionally be palpable
and it can be confused with enlarged lymph nodes or soft tissue
tumors. This muscular arch may cause intermittent compression
of the axillary vein and may lead to axillary venous thrombosis or
it may present clinically as a finding of fullness within the axilla. It
has also been reported to cause lymphatic compression with venous
thrombosis or lymphedema, or thoracic outlet obstruction and
shoulder instability syndrome. However, AA is usually asymptomatic
and its main importance is the problem it can cause during AL for
breast cancer. The presence of AA may limit access to the lower lateral
group of Level I axillary lymph nodes, thus resulting in an incomplete
axillary clearance. This obviously has serious implications for local
recurrence. Moreover, AA could be misregarded as the lateral border
of the AL -which normally is the anterior margin of the latissimus
dorci muscle- resulting to lead the surgeon one level above the
axillary vein with the associated risk of injuring the neurovascular
bundle of the axilla. Persistence of the AA after AL increases the
risk of upper limb lymphedema due to compression of the axillary
vein and the lateral lymphatic trunks. In cases of local recurrence
due to inadequate axillary clearance, the management becomes
difficult and the risk for local morbidity and lymphedema increases.
Since these complications are significant, researchers conclude that
AA should be identified and divided to allow adequate exposure
of axillary lymph nodes in order to achieve an uncomplicated, safe
and complete lymphatic dissection. Furthermore, the identification
of AA is important during SLNB, because of the need to adequate
exposure and good haemostasis during the procedure. Although
axillary dissection for breast cancer is the most common type of
axillary surgery there are other surgical procedures in the armpit
area which may be affected by the presence of AA, such as bypass
surgeries using axillary vessels. Additionally, ischaemic necrosis
can complicate LD-flap breast reconstruction if the AA stretches or
compresses the thoracodorsal pedicle. Therefore, all breast and/or
oncologic surgeons operating in the axilla region should be aware and
able to recognize axillary arch and its musculotendinous variations,
in order to determine a safe approach to the armpit. On the other
hand, the other rare muscles and tendonous arches, which either
pass through the axilla or change the boundaries of the AL surgical
field, may occasionally cause complications during AL. However,
there are no studies reporting intraoperative recognition of atypical
pectoralis quartus, chondroepitrochlearis and aplasia of the lower
part of pectoralis major muscles, and as a result their significance in
axillary surgery is not known. Nevertheless, preoperative diagnosis
of these anomalous muscles is difficult and apart from the AA, which
should be recognized during axillary dissection, the intraoperative
recognition of the other three muscular variations seems to be useful.
References
- Uzmansel D, Kurtoglou Z, Kara A, Ozturk NC. Frequency, anatomical properties and intervation of axillary arch and its relations to the brachial plexus in human fetuses. Surg Radiol Anat. 2010;32(9):859-63.
- Besana-Ciani I, Greenall MJ. Langer’s axillary arch: Anatomy, embryological features and surgical implications. Surgeon. 2005;3(5):325-7.
- Natsis K, Vlasis K, Totlis T, Paraskevas G, Noussios G, Skandalakis P, et al. Abnormal muscles that may affect axillary lymphadenectomy: surgical anatomy. Breast Cancer Res Treat. 2010;120(1):77-82.
- Daniels IR, Quersi della Rovere G. The axillary arch of Langer- the most common muscular variation in the axilla. Breast Cancer Res Treat. 2000;59(1):77-80.
- Standring S. Gray’s Anatomy, 39th ed. Edinburgh: Elsevier; 1962.
- Jatoi I, Kaufmann M, Petit JY. Anotomy. In: Atlas of breast surgery. Berlin: Springer-Verlag; 2006. p. 7-15.
- Jatoi I, Kaufmann M, Petit JY. Surgery for Breast Carcinoma. In: Atlas of Breast Surgery. Berlin: Springer-Verlag; 2006. p. 61-84.
- Manasseh DME, Willey SC. Invasive carcinoma: mastectomy and staging the axilla. In: Spear SL, editor. Surgery of the Breast. 2nd ed. Philadelphia: Lippinkott Williams&Wilkins, USA; 2006. p. 131-7.
- Delay E. Breast reconstruction with an autologous latissimus musculocutaneous flap with and without immediate nipple reconstruction. In: Spear SL, editor. Surgery of the Breast. 2nd ed. Philadelphia: Lippinkott Williams&Wilkins, USA; 2006. p. 631-55.