Langer's axillary arch: Anatomy, embryological features and surgical implications

Axillary arch muscle and pectoralis quartus: an unusual combination of two variant supernumerary muscles in the axillary region - a case report

Variant anatomy in the axillary region is of great clinical significance. It is one of the most frequently accessed regions for radical dissection surgery. During routine dissection of embalmed cadavers, we found a rare case of two accessory muscular slips emerging from the lateral border of latissimus dorsi (LD) and the inferolateral border of pectoralis major (PM), crossing the neurovascular structures in the axilla and merging distally together to the brachial fascia at the upper end of humerus below the bicipital groove. The accessory slip from LD is commonly referred to as the "axillary arch" in literature. We identified the accessory slip from the PM crossing over the axilla as pectoralis quartus. These aberrant slips can cause neurovascular compression in the axilla and can have clinical implications. Prior knowledge of the variant anatomy is the key to successful surgery in the axilla, thereby avoiding inadvertent injuries and post-operative complications.

Axillary arch (of Langer): A large-scale dissection and simulation study based on unembalmed cadavers of body donors

Connective or muscular tissue crossing the axilla is named axillary arch (of Langer). It is known to complicate axillary surgery and to compress nerves and vessels transiting from the axilla to the arm. Our study aims at systematically researching the frequency, insertions, tissue composition and dimension of axillary arches in a large cohort of individuals with regard to gender and bilaterality. In addition, it aims at evaluating the ability of axillary arches to cause compression of the axillary neurovascular bundle. Four hundred axillae from 200 unembalmed and previously unharmed cadavers were investigated by careful anatomical dissection. Identified axillary arches were examined for tissue composition and insertion. Length, width and thickness were measured. The relation of the axillary arch and the neurovascular axillary bundle was recorded after passive arm movements. Twenty-seven axillae of 18 cadavers featured axillary arches. Macroscopically, 15 solely comprised muscular tissue, six connective tissue and six both. Their average length was 79.56 mm, width 7.44 mm and thickness 2.30 mm. One to three distinct insertions were observed. After passive abduction and external rotation of the arm, 17 arches (63%) touched the neurovascular axillary bundle. According to our results, 9% of the Central European population feature an axillary arch. Approximately 50% of it bilaterally. A total of 40.74% of the arches have a thickness of 3 mm or more and 63% bear the potential of touching or compressing the neuromuscular axillary bundle upon arm movement.

Langer's arch in axillary dissections from patients with breast cancer: a retrospective study

PURPOSE

The study aimed to assess the frequency of Langer's arch in patients undergoing axillary dissection for breast cancer.

METHODS

From January-2015 to March-2020, in a general hospital in México City, female patients undergoing axillary dissection for breast cancer were studied. The analysis involved: demographic and anthropometric data, type of surgical treatment, histopathologic diagnosis, number of lymph nodes harvested, and frequency of Langer's arch finding.

RESULTS

The sample studied was 123 axillary dissections. The mean age of the patients was 59 ± 10.5-years. Modified radical mastectomy was done in 117 cases (95.1%). Ductal carcinoma occurred in 96 cases (78%). The mean number of lymph nodes harvested was 24 ± 6.5. Langer's arch finding occurred in 33 cases (26.8%).

CONCLUSION

Langer's arch is frequent in our patients undergoing axillary dissection for breast cancer.

Ultrasound Detection of the Axillary Arch as a Cause of Thoracic Outlet Syndrome: A Prospective Dissection-Controlled Cadaver Study

Ultrasound as a diagnostic tool in thoracic outlet syndrome (TOS) is becoming increasingly important. The aim of this study was to investigate the diagnostic value of ultrasound in detecting the axillary arch, an ancillary muscle potentially causing TOS. Two hundred upper limbs of 100 fresh, non-frozen, non-embalmed body donors were screened for axillary arches. Sonographic findings were validated by anatomic dissection. Twelve axillary arches were found in 200 upper extremities, corresponding to a prevalence of 8.0% per individual and 6.0% per upper extremity investigated. Ultrasound had low diagnostic performance in identifying axillary arches, with a sensitivity of 66.7% and specificity of 95.7%. There was a tendency to identify more easily arches consisting of purely muscle tissue. Axillary arch thickness, its cross-sectional area and the predominant tissue type were associated with compression of the neurovascular bundle during shoulder elevation. Ultrasound seems to have limited potential to identify axillary arches. However, arches consisting predominantly of muscle tissue may be identified more easily and were associated with compression of neurovascular structures, thus potentially causing symptoms. Further clinical trials are needed to clarify the true value of ultrasound in patients with symptoms of TOS.

Anatomical Variations of the Axillary Arch and Implications in Breast Surgery

INTRODUCTION

Langer's axillary arch (AA), the most common anatomical variant in the axillary area of definite clinical significance. This is an updated review of the reported variations in the structure, highlighting its morphological diversity and its potential in complicating axillary lymph node biopsy, lymphadenectomy, or breast reconstruction.

METHODS

A review of the literature concerning the AA published between 1812 and 2020 was performed using the PubMed, Scopus, Embase, and Cochrane medical databases. The frequency, laterality, morphology, origin, lateral attachment points, vascularization, and neurosis of the AA were the parameters retrieved from the collected data.

RESULTS

The prevalence of AA ranged from 0.8% to 37.5%. It is more often unilateral, muscular in nature, and extending from the latissimus dorsi to the pectoralis major. It is vascularized by the lateral thoracic vessels or the subscapular artery and innervated by the thoracodorsal nerve.

CONCLUSIONS

Langer's AA, when present, may complicate surgical procedures in the area; therefore, every surgeon performing breast or axillary surgery should be aware of this entity and its variations to ensure maximal effectiveness and safety in the management of patients.

[Focus on axillary anatomy: The Carl Langer muscle, a great forgotten muscle in the training of medical residents in gynecology and obstetrics]

OBJECTIVE

The Carl Langer muscle is the main anatomical variation of the walls of the axillary area, its incidence being about 7%. The presence of this muscle crossing the anterior edge of the axillary vessels can induce difficulties of exposure, location and dissection during axillary surgery. In addition, it may be responsible for primary lymphedema of the upper limb, venous thrombosis of the axillary vein or thoracic outlet syndrome due to vascular or nervous compression. The objective of this work was to evaluate the state of knowledge on Carl Langer muscle of the gynecology-obstetrics medical residents of the French Eastern Region.

MATERIAL AND METHODS

All the medical residents enrolled in the specialized diploma in gynecology-obstetrics in the 5 regions (Alsace, Bourgogne, Lorraine, Champagne-Ardenne and Franche-Comté) were questioned by means of a questionnaire sent by e-mail.

RESULTS

From February to March 2021, 94 of the 160 medical residents interviewed answered to the questionnaire. Ninety-one of them (97%) did not know Carl Langer's muscle. Three medical residents thought they knew this muscle (3%) but their knowledge was imperfect.

CONCLUSION

Our work has highlighted the general lack of knowledge of this anatomical variation, which is relatively frequent, among French gynecology-obstetrics medical residents who are required to examine or perform surgery on this area. This updated review of the literature should optimize the knowledge of the anatomy of the axillary area and consequently its surgery.

Anterior Axillary Arch: An Anatomic Variant Every Surgeon Operating in the Axilla Should Be Aware of

BACKGROUND

Anterior axillary arch (AAA) is a slip of latissimus dorsi muscle, of variable thickness, which crosses anterior to the axillary vessels and brachial plexus. It is the most common anatomic variant in the axilla and surgeons operating in this area should be familiar with this finding to prevent confusion and complications. The aim of this study is to enhance surgeon's awareness of AAA, report the prevalence, and to describe our experience with this anomaly.

METHODS

An institutionally maintained database was used to identify patients with AAA in a single surgeon's experience, from 2008 to 2019. Patient characteristics, including tumor type, laterality, and pathologic node counts were determined and compared with patients undergoing axillary lymph node dissection (ALND) without this anatomic anomaly.

RESULTS

Nineteen patients with AAA were identified (13 on ALND and 6 during sentinel lymph node biopsy). Indications for ALND included breast cancer (12), melanoma (5), and Merkel cell carcinoma (2). In patients with AAA undergoing an ALND, the median number of lymph nodes pathologically identified was 23 and similar to those without AAA (27, P = 0.14). The prevalence of AAA in patients who underwent ALND was 3.1% (13/422).

CONCLUSIONS

Surgeons who operate in the axilla are likely to encounter an AAA. Knowledge of this variant should improve operative efficiency and may prevent technical errors during an ALND or sentinel lymph node biopsy.

Anatomy of the axillary arch: from its incidence in human to an embryologic and a phylogenetic explanation of its origins

INTRODUCTION

Typically, the axillary arch is defined as a fleshy slip running from latissimus dorsi to the anterior aspect of the humerus. Phylogeny seems to give the most relevant and plausible explanation of this anatomical variant as a remnant of the panniculus carnosus. However, authors are not unanimous about its origin. We report herein the incidence of axillary arch in a series of 40 human female dissections and present an embryologic and a comparative study in three domestic mammals.

MATERIALS AND METHODS

Forty formalin-preserved Caucasian human female cadavers, one rat (Rattus norvegicus), one rabbit (Oryctolagus cuniculus) and one pig (Sus scrofa domesticus) cadavers were dissected bilaterally. A comparative, analytical and a descriptive studies of serial human embryological sections were carried out.

RESULTS

We found an incidence of axillary arch of 2.5% (n = 1 subject of 40) in Humans. We found a panniculus carnosus inserted on the anterior aspect of the humerus only in the rat and the rabbit but not in the pig. The development of the latissimus dorsi takes place between Carnegie stage 16-23, but the embryological study failed to explain the genesis of the axillary arch variation. However, comparative anatomy argues in favour of a panniculus carnosus origin of the axillary arch.

CONCLUSIONS

With an incidence of 2.5% of cases, the axillary arch is a relatively frequent variant that should be known by clinician and especially surgeons. Moreover, while embryology seems to fail to explain the genesis of this variation, comparative study gives additional arguments which suggest a possible origin from the panniculus carnosus.

Langer's arch: A rare but important consideration for axillary surgery with implications for training

Langer's arch (LA), although rare, is an important anatomical anomaly in the axilla that may be encountered during axillary lymph node dissection (ALND). Failure to recognize this anomaly may cause disorientation during ALND, resulting in inadequate clearance, with implications for local disease recurrence and inaccurate staging. Here, we present a case that highlights the confusion LA can cause even in experienced surgeons. With indications for ALND decreasing, resulting in lower operative numbers, surgeons are less likely to be exposed to this structure during their training. Improving knowledge and understanding of LA is important to ensure breast surgeons' preparedness for axillary surgery.

The Role of the Axillary Arch Variant in Neurovascular Syndrome of Brachial Plexus Compression

Axillary arch muscles are often found. In their course through this area, they might interfere with regional neurovascular structures. This case report will examine the presence of the axillary arch muscle and its implication in brachial plexus compression. During routine dissection of the left axilla and upper limb, a variant muscle (axillary arch muscle) was identified arising from the distal tendon of the latissimus dorsi and extending laterally to insert onto the deep surface of the tendon of insertion of the deltoid muscle. In adduction of the upper limb, the muscle was lax without compression of any underlying neurovascular structures. However, in abduction, the aberrant band of muscles compressed the proximal branches of the brachial plexus. Clinicians should be aware of this anatomical variant and its clinical significance in neurovascular compression including brachial plexus compression, thoracic outlet syndrome, and hyperabduction syndrome. This literature will review the anatomy of the axillary arch and its clinical correlate regarding signs, symptoms, diagnosis, and treatment in brachial plexus compression.

The panniculus carnosus muscle: an evolutionary enigma at the intersection of distinct research fields

The panniculus carnosus is a thin striated muscular layer intimately attached to the skin and fascia of most mammals, where it provides skin twitching and contraction functions. In humans, the panniculus carnosus is conserved at sparse anatomical locations with high interindividual variability, and it is considered of no functional significance (most possibly being a remnant of evolution). Diverse research fields (such as anatomy, dermatology, myology, neuroscience, surgery, veterinary science) use this unique muscle as a model, but several unknowns and misconceptions remain in the literature. In this article, we review what is currently known about panniculus carnosus structure, development, anatomical location, response to environmental stimuli and potential function(s), with the aim of putting together the evidence arising from the different research communities and raising interest in this unique muscle, which we postulate as an ideal model for both vascular and muscular research.

Prevalence and anatomy of the axillary arch and its implications in surgical practice: A meta-analysis

PURPOSE

The following research aimed to investigate the prevalence and anatomical features of the axillary arch (AA) - a muscular, tendinous or musculotendinous slip arising from the latissimus dorsi and that terminates in various structures around the shoulder girdle. The AA may complicate axillary lymph node biopsy or breast reconstruction surgery and may cause thoracic outlet syndrome.

METHODS

Major electronic databases were thoroughly searched for studies on the AA and its variations. Data regarding the prevalence, morphology, laterality, origin, insertion and innervation of the AA was extracted and included in this meta-analysis. The AQUA tool was used in order to assess potential risk of bias within the included studies.

RESULTS

The AA was reported in 29 studies (10,222 axillas), and its pooled prevalence estimate in this meta-analysis was found to be 5.3% of the axillas: unilaterally (61.6%) and bilaterally (38.4%). It was predominantly muscular (55.1% of the patients with the AA), originated from the latissimus dorsi muscle or tendon (87.3% of the patients with the AA), inserted into the pectoralis major muscle or fascia (35.2% of the patients with the AA), and was most commonly innervated by the thoracodorsal nerve (39.9% of the patients with the AA).

CONCLUSION

The AA is a relatively common variant, hence it should not be neglected. Oncologists and surgeons should consider this variant while diagnosing an unknown palpable mass in the axilla, as the arch might mimic a neoplasm or enlarged lymph nodes.

Langer's axillary arch: a frequent but rarely discussed anatomical variant in the radiologic literature

The axillopectoral muscle is a rarely discussed variant of muscular anatomy of the axilla, with various clinical implications. We report a case of a 7-year-old girl with multiple genetic and developmental abnormalities who presented with asymmetrical right axillary bulging of unknown etiology. MRI demonstrated a small accessory axillary muscle, known as Langer's axillary arch and/or the axillopectoral muscle. Other than soft-tissue asymmetry, the patient experienced no additional related symptoms. However, this is an important variant to be aware of, as it can easily be discovered on imaging and may be a causative agent for various upper extremity symptoms that may resolve with appropriate recognition and surgical intervention.

Variants of latissimus dorsi with a perspective on tendon transfer surgery: an anatomic study

BACKGROUND

The latissimus dorsi (LD) is often used for tendon transfers to treat massive irreparable posterosuperior rotator cuff tears. The operation requires the LD tendon to be mobilized to reduce tension on the tendon. In that respect, any connection between the LD tendon and contiguous muscles may hamper tendon mobility and affect the surgical outcome. The goal of this study was to document the occurrence of connections between the LD and adjacent muscles and nerves.

METHODS

We studied the scapular region on 48 embalmed cadavers. The skin and superficial fascia were removed according to Cunningham's manual of dissection, and the muscle was exposed.

RESULTS

It was found that the LD and teres major (TM) muscles are connected by muscle fibers in 10% of the cadavers studied. Another vital discovery was that in some cadavers, the LD tendon was penetrated by a nerve.

CONCLUSION

Fascial connections between the LD and TM are well known, but these muscle links are comparatively unusual. From the results of this study, one should pay particular attention to muscle links between the LD and TM during dissection of the LD for transfer. It can also be suggested that during transfer surgery, the LD tendon should be cautiously examined for the possibility of a nerve penetrating it.

Muscular axillary arch accompanying variation of the musculocutaneous nerve: axillary arch

Continuous attention has been developed on the anatomical variations of the axilla in anatomist and surgeon due to their clinical importance. The axillary region is an anatomical space between the lateral part of the chest wall and the medial aspect of the upper limb. During the routine dissection of embalmed cadavers, we found variant muscular slip originating from the lateral border of tendinous part of the latissimus dorsi and continuing 9 cm more crossing the axilla. And then, it inserted into the superior margin of the insertion of the pectoralis major. We considered this muscular variation as axillary arch muscle. Correct identification of the relevant anatomy and subsequent simple surgical division is curative, paying special attention to anatomical variations in this region and its clinical importance due to its close relationship to the neurovascular elements of the axilla.

Variation of the latissimus dorsi

A typical muscle variation of latissimus dorsi — the axillary arch is represented by the muscular or fibromuscular slip detached from the anteroinferior border of the musculus latissimus dorsi passing over the axilla under the axillary fascia crossing the medial side of the brachial plexus to continue as a septum intermusculare mediale brachii distally to the medial epicondyle of humerus. The full extent of the muscle is rarely present. Slips of muscle extend from the latissimus dorsi at the inferior angle of scapula to insert into pectoralis major (Langer), coracobrachilis, biceps or coracoid process forming what is described as a common variant - the muscular axillary arch. We report three cases of variants of latissimus dorsi, one of which has not been reported in the literature before.

Muscular variations during axillary dissection: a clinical study in fifty patients

AIM

The present study was conducted to detect the musculature variations during axillary dissection for breast cancer surgery.

METHODS

The anatomy of axilla regarding muscular variations was studied in 50 patients who had an axillary dissection for the staging and treatment of invasive primary breast cancer over one year.

RESULTS

In a period of one year, two patients (4%) with axillary arch and one patient (2%) with absent pectoralis major and minor muscles among fifty patients undergoing axillary surgery for breast cancer were identified.

CONCLUSIONS

Axillary arch when present should always be identified and formally divided to allow adequate exposure of axillary contents, in order to achieve a complete lymphatic dissection. Complete absence of pectoralis major and minor muscles precludes the insertion of breast implants and worsens the prognosis of breast cancer.

Clinical significance of the axillary arch in sentinel lymph node biopsy

Purpose

The axillary arch is an anomalous muscle that is not infrequently encountered during axillary sentinel lymph node biopsy (SLNB) of breast cancer patients. In this study, we aimed to investigate how often the axillary arch is found during SLNB and whether it affects the intraoperative sentinel lymph node (SLN) identification rate.

Methods

We retrospectively analyzed the correlation between the presence of the axillary arch and the SLN sampling failure rate during SLNB in 1,069 patients who underwent axillary SLNB for invasive breast cancer.

Results

Of 1,069 patients who underwent SLNB, 79 patients (7.4%) had the axillary arch present. The SLNB failure rate was high when the patient's body mass index was ≥25 (p=0.026), when a single SLN mapping technique was used (p=0.012), and when the axillary arch was present (p<0.001). These three factors were also found to be statistically significant by multivariate analysis, and of these three factors, presence of the axillary arch most significantly increased the SLNB failure rate (hazard ratio, 10.96; 95% confidence interval, 4.42-27.21; p<0.001). Additionally, if the axillary arch was present, the mean operative time of SLNB was 20.8 minutes, compared to 12.5 minutes when the axillary arch was not present (p<0.001). If the axillary arch was present, the SLN was often located in a high axillary region (67%) rather than in a general low axillary location.

Conclusion

The axillary arch was found to be a significant factor affecting intraoperative SLN failure rate. It is necessary to keep in mind that carefully checking the high axillar region during SLNB in breast cancer patients with the axillary arch is important for reducing SLN sampling failure.

Anatomical variations of the axilla

Purpose

The present study aimed to measure the thickness of the subcutaneous adipose tissue (SAT) at the site of the surgical incision for axillary lymph node dissection (ALND) and to record potential anatomical variations in the medial cutaneous nerve of the arm (MCNA), the intercostobrachial nerve (ICBN), the lateral thoracic vein (LTV), the lateral thoracic artery (LTA) and the pectoral muscle pedicle (PMP), considering that some details of the anatomy of these structures within the axilla are still unclear.

Methods

A prospective study was conducted in 100 consecutive patients with breast cancer who underwent ALND as part of surgical treatment. The anatomy of the dissected axilla was video recorded.

Results

The SAT thickness ranged from 8 mm to 60 mm, with an average thickness of 25.9 mm. A positive correlation was observed between the SAT thickness and the body mass index (BMI) of the evaluated patients (r = 0.68; p < 0.0001). The MCNA was the anatomical structure that was least commonly observed in the axilla (22% of cases), while the PMP was the most constant element, identified in 100% of cases. All of the studied anatomical structures observed within the axilla showed variation in at least one of the aspects analyzed, i.e., the point of entry and exit, path, number and location of divisions or branches.

Conclusion

The present study demonstrated wide variation in thickness of the SAT overlying the axilla and identified the existence of broad normative anatomical variation of the axilla.

Electronic supplementary material

The online version of this article (doi:10.1186/2193-1801-3-306) contains supplementary material, which is available to authorized users.

Duplicated axillary arch muscles arising from the latissimus dorsi

Many origins and insertions of an axillary muscular slip (also known as Langer's or axillary arch muscles) have been documented previously. In this report, we found duplicated axillary arch muscles (two variant muscular slips) originating from the inferolateral border of the right side latissimus dorsi muscle. Obviously, these axillary arch muscles can be distinguished as short and long muscular strips. While the origin was the same, the short muscular slip inserts into the fascia covering on the pectoralis minor, whereas the longer one inserts on/into the aponeurosis of pectoralis major. For the surgery in the axillary region, this rare variation should be considered a cause of surgical interventions.

The innervation of the axillary arch determined by surface stimulodetection electromyography

The axillary arch (AA) is a muscular anatomical variation in the fossa axillaris that has been extensively studied in cadaveric specimens. Within these dissections, different innervations of the AA have been proposed, but this has never been explored in vivo. Knowledge of the innervation of the AA is required in order to better understand its function (e.g. predisposition for certain sports and/or activities, understanding shoulder injuries in overhead sports). Here, we report on the use of surface stimulodetection electromyography (SSEMG) to resolve the innervation of the AA in 20 subjects (12 women, eight men - mean age of 21.3 ± 2.7 years) with a uni- or bilateral AA. SSEMG of each muscle [M. latissimus dorsi (MLD) and M. pectoralis major] was performed with a four-channel electrostimulation measuring system in order to determine the innervation of the AA. The results showed co-contraction of the MLD in 85% of the subjects after AA stimulation. In the remaining subjects, no specific localized response was observed due to non-specific nerve stimulation, inherent to the proximity of the brachial plexus in these individuals. Our findings demonstrate that SSEMG exploration offers a practical and reliable tool for investigating anatomical aspects of muscle innervation in vivo. Using this approach, we conclude that the AA receives the same innervation as the MLD (the N. thoracodorsalis), and may be considered a muscular extension of the latter.

Preoperative diagnosis of the axillary arch with multidetector row computed tomography and the axillary arch in association with anatomical problems of sentinel lymph node biopsy

BACKGROUND

The purpose of this study was to describe the preoperative diagnosis of the axillary arch with multidetector row computed tomography (MDCT) in patients who underwent sentinel lymph node (SLN) biopsy. In addition, we investigated anatomical problems of SLN biopsy in the cases that diagnosed this anomaly.

METHODS

From 2003 to 2008, combined procedures with blue dye SLN biopsy and MDCT-assisted axillary node sampling were performed in 550 clinically axilla-negative patients with primary operable breast cancer. We use MDCT for not only the diagnosis of the axillary arch, but also the planning and navigation of SLN biopsy.

RESULTS

The axillary arches were preoperatively diagnosed with MDCT in 59 patients (10.8%) as follows: a single ordinary axillary arch (n = 44), another anomalous muscle besides the ordinary axillary arch (n = 13), and other rare axillary arches (n = 2). The SLN identification failure rate was 1.8% (9/491) for patients without the axillary arch and 5.1% (3/59) for patients with the axillary arch (chi-square test, P = 0.11). Three patients with an axillary arch in whom a SLN could not be identified were observed in 13 patients who had another anomalous muscle besides the ordinary axillary arch (3/13, 23.1%). In the examination of 56 patients with an axillary arch in whom a SLN was identified, variations of the SLN location and/or anomalous muscles covering a SLN were observed in 16 patients (28.5%).

CONCLUSIONS

MDCT is useful for a diagnosis of the axillary arch. The axillary arch should be kept in mind during SLN biopsy because this anomaly would be related to anatomical variations that affect SLN biopsy.

The Muscular Axillary Arch: An Anatomic Study and Clinical Considerations

Objective:

The muscular axillary arch is a musculotendinous structure that arises from the latissimus dorsi muscle and crosses the axilla before inserting to the humerus, brachial fascia, or coracoid process. Case reports have described the neurovascular compression symptoms caused by this anatomic variant and have reported that the symptoms can be relieved by division of the muscle. However, there has been little information published regarding this topic in the neurosurgical literature.

Methods:

We evaluated 70 axillary dissections in 35 cadavers to assess for the presence of this anomaly.

Results:

The muscular axillary arch was identified unilaterally in 3 (8.6%) of the 35 cadavers. All 3 arches arose from the anterior border of the latissimus dorsi muscle and inserted at a point along a line extending from the coracoid process to the intertubercular groove deep to the insertion of the pectoralis major muscle. All 3 arches crossed over the neurovascular bundle in the axilla.

Conclusion:

Compression by the muscular axillary arch should be considered in the differential diagnosis of patients with thoracic outlet and hyperabduction syndromes.

Axillary arch in human: common morphology and variety. Definition of "clinical" axillary arch and its classification

In this work the authors summarize the extensive information available concerning the best-known variant muscular structure in the region of the human axilla--the axillary arch. Emphasis has been placed on the common morphology and variety of the axillary arches. From the anatomical descriptions, the authors extract the characteristics of a group of "typical" axillary arches and also noted the descriptions of a group of "unusual" axillary arches found in the recent literature. The axillary arch terminology, incidence in human population, innervation and origin are discussed. The clinical significance of the axillary arch is presented briefly and the need of a new concept for the axillary arch is stated. In conclusion, for the purpose of clinical practice, a new term--"clinical" axillary arch is defined, and its proper clinically oriented classification is presented.

Axillary arch in Bulgarian population: clinical significance of the arches

In order to study the incidence of the axillary arch in the Bulgarian population, we examined the axillary regions of 56 formol-carbol fixed human cadavers and observed two cases with a unilateral axillary arch. In the first case, the variant structure was situated on the right side of a 58-year-old female cadaver. The axillary arch extended from the lateral border of the latissimus dorsi to the posterior layer of the pectoralis major tendon. In the second case, the axillary arch was found on the left side of a 63-year-old male cadaver and had the same attachment points as in the first case. The innervation and blood supply of the arches are discussed. We have also reviewed extensive information concerning the clinical importance of the axillary arch, and for the first time, it was summarized clearly for clinicians. The summary consists of three parts: "diagnosis" of the axillary arch by physical investigation or imaging techniques; the axillary arch and surgical interventions in the region of the axilla; the axillary arch as an entrapment site for the axillary vessels and nerves.

L'arche et la sentinelle: techniques chirurgicales de la lymphadénectomie axillaire sentinelle en présence du muscle pectoro-axillaire

OBJECTIVE

Identify the axillopectoral muscle (usually called Langer's axillary arch) and know the main surgical techniques of axillary sentinel node biopsies.

PATIENTS AND METHODS

We present the results of our five-year clinical prospective study: the presence of this anomaly is diagnosed peroperatively during a sentinel node biopsy.

RESULTS

Langer's arch is identified in 1,7%, often with an unilateral distribution. Lymph nodes are just near or behind the muscle. Sentinel node biopsy dissection is difficult in about 40%.

DISCUSSION AND CONCLUSION

The embryological derivation and anatomical features of this muscle are described, with emphasis on the surgical applications. Its presence or absence should be ascertained in every sentinel node biopsy because of the risks of axillary dissection complications by this ectopic muscle.