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

Identification and characterization of a potentially novel dorsal cutaneous muscle in rodents

In the course of performing a detailed dissection of adult rat to map the cutaneous nerves of cervical, thoracic, and lumbar levels a small and unexpected structure was isolated. It appeared to be a cutaneous striated muscle and was observed in both male and female rats and in mice but absent from cats and humans. With the skin reflected laterally from midline, the muscle lies closely apposed to the lateral border of the Thoracic Trapezius (Spinotrapezius) muscle and is easily missed in standard gross dissections. Focussed prosections were performed to identify the origin, insertion, and course of gross innervation. Identification of each of these elements showed them to be distinct from the nearby Trapezius and Cutaneous Trunci (Cutaneous Maximus in mouse) muscles. The striated muscle nature of the structure was validated with whole-mount microscopy. Consulting a range of published rodent anatomical atlases and gross anatomical experts revealed no prior descriptions. This preliminary report is an opportunity for the anatomical and research communities to provide input to either confirm the novelty of this muscle or refer to prior published descriptions in rodents or other species while the muscle, its innervation, and function are further characterized. Presuming this muscle is indeed novel, the name "Cutaneous Scapularis muscle" is proposed in accord with general principles of the anatomical field.

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.

Arco axilar de Langer: serie de casos y revisión de la literatura

Introducción. El arco de Langer es una entidad infrecuente, cuya prevalencia depende de la técnica quirúrgica utilizada y usualmente no se asocia con síntomas de compresión vascular o neuronal. El objetivo de este estudio fue describir las características clínicas y morfológicas, y la proporción de síntomas de compresión neurovascular del arco de Langer, en mujeres con cáncer de mama llevadas a cirugía axilar. Métodos. Estudio descriptivo del arco de Langer en mujeres con cáncer de mama, llevadas a cirugía axilar en el registro personal de un cirujano, en Medellín, Colombia, entre el 1 enero de 2017 y el 15 agosto de 2020. Se evaluaron características clínicas, morfológicas y síntomas de compresión neurovascular. Las variables categóricas se agruparon según su frecuencia como porcentajes, y para las variables continuas se calculó la mediana y su rango intercuartílico. Resultados. Entre el 1 enero de 2017 y el 15 agosto de 2020 se realizaron 725 cirugías axilares, 479 biopsias de ganglio centinela y 246 linfadenectomías, encontrando 17 casos de arco de Langer, para una frecuencia de 2,3 %. Fue más frecuente encontrarlo en el curso de una linfadenectomía (n=11, 64,7 %). En 15 (88,2 %) casos se presentó riesgo de ocultamiento ganglionar y en 14 (82,3 %) generó dificultad quirúrgica. No hubo casos con síntomas de compresión vascular o neuronal. En ningún caso se realizó el diagnostico imagenológico prequirúrgico. La conducta quirúrgica predominante fue sección, en 88,2 %, sin presentar complicaciones quirúrgicas asociadas. Discusión. Es importante para el cirujano el conocimiento del arco axilar como una variante anatómica de la axila, que puede ocultar los ganglios o dificultar la disección axilar, por lo que la conducta más usada es la sección.

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.

Variations of the musculofascial axillary arch with the adjacent lymph nodes

PURPOSE

This unique case gives the extent of knowledge in the axilla area with axillary arch (AA) and a discussion of its clinical importance.

MATERIALS AND METHOD

The anatomical anomaly was found during the dissection class for the brachial plexus. It was identified through the precise dissection of the structures bilaterally.

RESULTS

The cadaver had fascial and muscular AA bilaterally. The fascial AA was separated into the superficial and deep arch group. The superficial arch group connected to the clavipectoral fascia and the axillary fascia. The deep arch group attached to the subscapular fascia. The muscular AA had superficial and deep variations. The superficial muscular AA attached between accessory slip of latissimus dorsi muscle (LDa) and pectoralis quartus muscle (PQ). The deep muscular AA attached to the crest of lesser tubercle of the humerus from LDa. The adipose tissue with the level one central lymph node was located lateral to the pectoralis minor muscle expand from pectoral lymph node through between LDa and PQ.

CONCLUSION

This case showed the fascial and muscular AA together. The muscular AA had both complete and incomplete attachment types. It could give functional and neurological problems in the axilla, such as thoracic outlet syndrome. Additionally, the structures presented with the axillary lymph node. It helps to understand the patient's condition with the AA in the axilla and could provide.

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.

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.

Langer's arch: a rare anomaly affects axillary lymphadenectomy

Langer's arch is the best-known anatomic variant of definite surgical implication in the region of the axilla. This rare anomaly is a muscular slip extending from the latissimus dorsi (LD) muscle to the tendons, muscles or fasciae around the superior part of the humerus. In this report, we present a rare case of left axillary arch. During modified radical mastectomy for breast cancer, we encountered an abnormal muscle slip crossing the axilla from the LD muscle to the posterior surface of the pectoralis major muscle anterior to the neurovascular structures. Preoperative knowledge is essential to identify such unusual anomaly and avoid potential complications both intra- and postoperatively.

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.

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.

In vivo study of the surgical anatomy of the axilla

Background

Classical anatomical descriptions fail to describe variants often observed in the axilla as they are based on studies that looked at individual structures in isolation or textbooks of cadaveric dissections. The presence of variant anatomy heightens the risk of iatrogenic injury. The aim of this study was to document the nature and frequency of these anatomical variations based on in vivo peroperative surgical observations.

Methods

Detailed anatomical relationships were documented prospectively during consecutive axillary dissections. Relationships between the thoracodorsal pedicle, course of the lateral thoracic vein, presence of latissimus dorsi muscle slips, variations in axillary and angular vein anatomy, and origins and branching of the intercostobrachial nerve were recorded.

Results

Among a total of 73 axillary dissections, 43 (59 per cent) revealed at least one anatomical variant. Most notable variants included aberrant courses of the thoracodorsal nerve in ten patients (14 per cent)—three variants; lateral thoracic vein in 12 patients (16 per cent)—four variants; bifid axillary veins in ten patients (14 per cent); latissimus dorsi muscle slips in four patients (5 per cent); and variants in intercostobrachial nerve origins and branching in 26 patients (36 per cent). The angular vein, a subscapular vein tributary, was found to be a constant axillary structure.

Conclusion

Variations in axillary anatomical structures are common. Poor understanding of these variants can affect the adequacy of oncological clearance, lead to vascular injury, compromise planned microvascular procedures and result in chronic pain or numbness from nerve injury. Surgeons should be aware of the common anatomical variants to facilitate efficient and safe axillary surgery.

A rare case of multiple neuromuscular variations in the axilla and arm

During the dissection of a 73-year-old embalmed male cadaver, we noted unusual variations in the flexor compartment of the upper limb-bilateral axillary arch muscles, a three-headed biceps brachii muscle with two supernumerary bellies-and variations in the origin of the musculocutaneous and median nerves from the brachial plexus. The morphological and clinical significance of this unique coexistence of multiple neuromuscular variations are discussed.

Variety of transversus thoracis muscle in relation to the internal thoracic artery: an autopsy study of 120 subjects

Background

The transversus thoracis muscle is a thin muscular layer on the inner surface of the anterior thoracic wall that is always in concern during harvesting of the internal thoracic artery. Because the muscle is poorly described in the surgical literature, the aim of the present study is to examine in details its variations.

Methods

The data was obtained at standard autopsies of 120 Caucasian subjects (Bulgarians) of both sexes (97 males and 23 females), ranging in age from 18 to 91 years (mean age 52.8 ± 17.8 years). The transversus thoracis morphology was thoroughly examined on the inner surface of the chest plates collected after routine incisions.

Results

An overall examination revealed that in majority of cases the transversus thoracis slips formed a complete muscular layer (left - 75.8%, right - 83.3%) or some of the slips (left - 22.5%, right - 15%) or all of them (left - 1.7%, right - 1.7%) were quite separated. Rarely (left - 3.3%, right - 5.8%), some fibrous slips of the transversus thoracis were noted. In 55.8% of the cases there was left/right muscle symmetry; 44.2% of the muscles were asymmetrical. Most commonly, the highest muscle attachment was to the second (left - 53.3%, right - 37.5%) or third rib (left - 29.2%, right - 46.7%). The sixth rib was the most common lowest attachment (left - 94.2%, right - 89.2%). Most frequently, the muscle was composed of four (left - 31.7%, right - 44.2%) or fifth slips (left - 53.3%, right - 40.8%).

Conclusions

This study provides detailed basic information on the variety of the transversus thoracic muscle. It also defines the range of the clearly visible, uncovered by the muscle part of the internal thoracic artery and the completeness of the muscular layer over it. The knowledge of these peculiar muscle-arterial relations would definitely be beneficial to cardiac surgeon in performing fast and safe arterial harvesting.

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.