What is the axillary arch (of Langer)?

We read with great interest the article by Weninger et al. (2023) on the presence of the axillary arch (AA) (of Langer) found during anatomical dissections-"Axillary arch (of Langer): A large-scale dissection and simulation study based on unembalmed cadavers of body donors." The authors performed their study using 400 axillae from 200 unembalmed cadavers; they identified this variant muscle in 27 axillae of 18 cadavers. Weninger et al. (2023) described the muscular AA in 15 cases; AA was composed of connective tissue in six cases, and AA comprised muscular and connective tissue in six cadavers. Moreover, these authors indicated that after passive abduction and lateral rotation of the arm, 17 arches (63%) came into contact with the neurovascular axillary bundle, which is of clinical importance. In our opinion, this is the most precise and detailed AA muscle study in the literature, illustrated with excellent photographs and schemes. Such studies expand the existing data in the literature and are of real help to clinicians. However, we want to present our modest comments about the title of the article and would like to pose the question, "What is the axillary arch (of Langer)?" Weninger et al. (2023) stated that connective or muscular tissue crossing the axilla is termed the AA (of Langer). This structure splits from the latissimus dorsi muscle, crosses the axilla, and joins the anterior part of the upper limb. The first detailed description of this variation was published in 1846 by Karl Langer Ritter von Edenberg (Langer, 1846). Nowadays, a significant number of articles term all muscular and fibromuscular connections between the latissimus dorsi muscle and the anterior part of the upper limb as "Langers AA" (Markou et al., 2023; Sang et al., 2019; Scrimgeour et al., 2020; Taterra et al., 2019). What Langer described in his work "Zur anatomie des musculus latissimus dorsi" was a fibrous thickening of the medial edge of the axillary fascia between the borders of the pectoralis major and the latissimus dorsi muscles, a structure he termed "Achselbogen." In a sequel of this article, Langer investigated muscular fibers inserting at or encircling the connective tissue "Achselbogen" (Langer, 1846). Therefore, in our opinion, in the study of Weninger et al. (2023), the term AA (of Langer) should only be used to describe the cases presenting solely with a connective tissue "arch" or these comprised of both, muscular and connective tissue. Weninger et al. (2023) noted that muscle fibers could not be excluded in these cases. Of course, to answer this question accurately, a histological study of these cases would be necessary.

Anatomy of the nerves to the teres minor and the long head of the triceps brachii for electromyography.

BACKGROUND: We investigated the branching pattern and topographic anatomy of the nerves to the teres minor (Tm) and the long head of the triceps brachii (LHT) in relation to reference lines extending between surface landmarks, to identify the innervation patterns of, and the optimal needle placement points within, the Tm and the LHT. METHODS: The anatomical courses of the nerves to the Tm and the LHT were investigated in 37 upper limbs of fresh-frozen cadavers. Distances from the acromion to nerve penetration points, and crossing points of reference lines with the Tm and LHT were measured in 27 cadaveric upper limbs. RESULTS: The Tm was innervated by the axillary nerve in all specimens in three patterns, and the LHT was innervated exclusively by the radial nerve. Our dissection and measurements indicate that the midpoint of the reference line from the acromion to the inferior angle of the scapula is the optimal needle insertion point for the Tm. The target point for the LHT appears to be the one-third point of the reference line from the acromion to the medial epicondyle, or the two-thirds point of the reference line from the acromion to the axillary fold. CONCLUSIONS: We investigated the branching pattern of the nerves to the Tm and the LHT and propose optimal needle placement points for electromyography of the Tm and LHT.

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.

Ultrasonographic study of a modified axillary approach to block the major branches of the brachial plexus in dogs.

OBJECTIVE: To provide ultrasonographic mapping of the axillary region of dogs to facilitate identification of the major branches of the brachial plexus in relation to the axillary artery. STUDY DESIGN: Prospective study. ANIMALS: A total of two dog cadavers and 50 client-owned, healthy dogs weighing >15 kg. METHODS: In Phase 1, anatomical dissections were performed to identify the relation of the major brachial plexus nerves to the axillary artery. In Phase 2, with the dogs in dorsal recumbency with thoracic limbs flexed naturally, the axillary space was scanned using a linear array probe oriented on the parasagittal plane until the axis transverse to nerves was found. Then, the transducer was rotated to a slight lateral angle approximately 30° to midline. The examination aimed to identify the axillary artery and the musculocutaneous, radial, median and ulnar nerves in addition to determining their position and distribution in four predefined sectors. RESULTS: The musculocutaneous nerve was observed in all animals cranial to the axillary artery. The radial, ulnar and median nerves were distributed around the axillary artery, with >90% on the caudal aspect of the axillary artery (sectors 1 and 2). CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasonography identified the location of the brachial plexus nerves near the studied sectors, providing useful guidance for performing a brachial plexus nerve block.

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.

The Accessory muscles of the Axilla.

The axilla is a region of clinical and surgical importance with plenty of anatomical variations. One of these is the presence of accessory muscles. The literature was reviewed in order to identify the different supernumerary muscles that are described in the axilla. Variant muscle slips arising from the pectoral muscle or latissimus dorsi muscle have been described. There still remains controversy regarding the phylogenetic origin of these different muscles. We described the most frequently reported muscles, their origin, and course. Further research is required regarding the innervation and influence on glenohumeral and scapulothoracic kinematics.

Ultrasound-guided anterior approach to the axillary and intercostobrachial nerves in the axillary fossa: an anatomical investigation.

BACKGROUND: The posterolateral and medial aspect of the arm is supplied by the axillary (AXN) and intercostobrachial nerves (ICBN), which are not anaesthetised by an axillary brachial plexus block (ABPB). Blockade of the AXN and the ICBN has been reported in the quadrangular space (QS) posteriorly or by serratus plane block, respectively. An anterior ultrasound-guided approach to block the AXN and ICBN would be desirable to complete an ABPB at a single insertion site. METHODS: After a preliminary dissection study in six cadavers, ultrasound-guided AXN and ICBN injection was performed in 46 Thiel embalmed cadavers bilaterally. Key sonographic landmarks to identify the AXN in the QS are the humerus, teres major muscle, and subscapular muscle. With the same probe position, the ICBN was identified in the subfascial axillary space. Then, 2 ml latex was injected at each nerve and confirmed by dissection. RESULTS: Muscular and bony landmarks were identified in all cadavers. The AXN was seen in 99% in the QS or at the inferolateral margin of the subscapular muscle and surrounded by latex in 96% of cases. Latex spread to the axillary fossa, within the subscapular muscle, or to the radial nerve was noted in 8% of the injections. The ICBN was seen and surrounded by latex in 100% of cases. CONCLUSIONS: We describe a reliable ultrasonographic approach to visualise the AXN and ICBN anteriorly from the conventional ABPB approach as confirmed in this cadaver study.

What is the variability in shoulder, axillae and waist position in a group of adolescents?

The clinical assessment of scoliosis is based on the recognition of asymmetry. It is not clear what the degree of asymmetry is in a population without scoliosis, which could make the differentiation between abnormal and normal uncertain. This study defines the range of normality in certain parameters of torso shape that are also associated with the clinical assessment of scoliosis. This was done by analysing the surface topography of a group of 195 children serially measured over a 5-year period. The analysis considered both the spinal curvature and the relative position of shoulders, axillae and waist on each side. The bivariate relationships were examined using 95% confidence interval data ellipses. Our results showed that a degree of spinal curvature was seen, either as a main thoracic or main thoracolumbar curve. The distribution of the data about a mean point is illustrated by 95% confidence interval (CI) data ellipses with shoulder, axilla and waist data plotted against spinal curvature. The mean values were close to zero (exact symmetry) for all of the measured parameters, with the ellipses showing little differences in the distributions. We conclude that mild asymmetry of the measured torso parameters is normal. These results define what is normal and beyond what point asymmetry becomes abnormal. This information is of use for those managing and counselling patients with scoliosis both before and after surgery.

Aberrant Cutaneous Nerve Loops in the Axilla.

During routine dissection classes, conducted for first year undergraduate medical students, we encountered a rare anatomical variation in relation to the intercostobrachial nerve (ICBN). The ICBN represents the lateral undivided cutaneous branch of second intercostal nerve. In this case, the ICBN formed nerve loops with branches of the lateral cutaneous branch of the third intercostal nerve. These loops eventually gave branches that probably supplied the floor of the axilla and proximal arm. Nowadays, this ICBN is gaining clinical importance during the axillary lymph node dissections and mammary gland surgeries. Damage to the ICBN, may results in the sensory deficits in patients undergoing surgery. In our case report, ICBN was making aberrant nerve loop along with the branches from the third intercostal nerve. Knowledge regarding the origin, formation and route of ICBN is of clinical significance to axillary surgeons, radiologist and anesthesiologists.

Defining the minimum anatomical coverage required to protect the axilla and arm against penetrating ballistic projectiles.

INTRODUCTION: Defining the minimum anatomical structural coverage required to protect from ballistic threats is necessary to enable objective comparisons between body armour designs. Current protection for the axilla and arm is in the form of brassards, but no evidence exists to justify the coverage that should be provided by them. METHOD: A systematic review was undertaken to ascertain which anatomical components within the arm or axilla would be highly likely to lead to either death within 60 min or would cause significant long-term morbidity. RESULTS: Haemorrhage from vascular damage to the axillary or brachial vessels was demonstrated to be the principal cause of mortality from arm trauma on combat operations. Peripheral nerve injuries are the primary cause of long-term morbidity and functional disability following upper extremity arterial trauma. DISCUSSION: Haemorrhage is managed through direct pressure and the application of a tourniquet. It is therefore recommended that the minimum coverage should be the most proximal extent to which a tourniquet can be applied. Superimposition of OSPREY brassards over these identified anatomical structures demonstrates that current coverage provided by the brassards could potentially be reduced.

Effect of Glenoid Bone Loss and Shoulder Position on Axillary Nerve Anatomy During the Latarjet Procedure.

BACKGROUND: The Latarjet procedure is increasingly being utilized for the treatment of glenoid bone loss and has a relatively high neurological complication rate. Understanding the position-dependent anatomy of the axillary nerve (AN) is crucial to preventing injuries. PURPOSE: To quantify the effects of changes in the shoulder position and degree of glenoid bone loss during the Latarjet procedure on the position of the AN. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 10 cadaveric shoulders were dissected, leaving the tendons of the rotator cuff and deltoid for muscle loading. The 3-dimensional position of the AN was quantified relative to the inferior glenoid under 3 conditions: (1) intact shoulder, (2) Latarjet procedure with 15% bone loss, and (3) Latarjet procedure with 30% bone loss. Measurements were obtained at 0°, 30°, and 60° of glenohumeral abduction (equivalent to 0°, 45°, and 90° of shoulder abduction) and at 0°, 45°, and 90° of humeral external rotation (ER). RESULTS: Abduction of the shoulder to 60° resulted in a posterior (9.5 ± 1.1 mm; P < .001), superior (3.0 ± 1.2 mm; P = .013), and lateral (19.1 ± 2.3 mm; P < .001) shift of the AN, and ER to 90° resulted in anterior translation (10.0 ± 1.2 mm; P < .001). Overall, ER increased the minimum AN-glenoid distance at 30° of abduction (14.9 ± 1.3 mm [0° of ER] vs 17.3 ± 1.5 mm [90° of ER]; P = .045). The Latarjet procedure with both 15 and 30% glenoid bone loss resulted in a superior and medial shift of the AN relative to the intact state. A decreased minimum AN-glenoid distance was seen after the Latarjet procedure with 30% bone loss at 60° abduction and 90° ER (17.7 ± 1.6 mm [intact] vs 13.9 ± 1.6 mm [30% bone loss]; P = .007), but no significant differences were seen after the Latarjet procedure with 15% bone loss. CONCLUSION: Abduction of the shoulder induced a superior, lateral, and posterior shift of the AN, and ER caused anterior translation. Interestingly, the Latarjet procedure, when performed on shoulders with extensive glenoid bone loss, significantly reduced the minimum AN-glenoid distance during shoulder abduction and ER. These novel findings imply that patients with substantial glenoid bone loss may be at a higher risk of AN injuries during critical portions of the procedure. Consequently, it is imperative that surgeons account for alterations in nerve anatomy during revision procedures. CLINICAL RELEVANCE: This study attempts to improve understanding of the position-dependent effect of shoulder position and glenoid bone loss after the Latarjet procedure on AN anatomy. Improved knowledge of AN anatomy is crucial to preventing potentially devastating AN injuries during the Latarjet procedure.

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.

Clinico-embryological submission of an unilateral anomalous presentation of axillary artery.

OBJECTIVES: Descriptions of the variant arterial pattern of upper limb are not exceptional and are therefore frequently reported in anatomy archives. BACKGROUND: A noteworthy deviation from the usual branching pattern was observed unilaterally in a single cadaver. This unique division of axillary artery (AA) was present on the right side in an adult human cadaver of Indian origin. RESULTS: The first part of axillary artery gave off the superior thoracic and thoraco-acromial arteries. Just proximal to the upper border of pectoralis minor the AA was observed to divide into two trunks a medial and a lateral. The lateral trunk continued into the brachium as the usual axillary artery where as the medial trunk displayed the other branches deep and distal to the pectoralis minor muscle. The remarkable feature was the wide caliber of the axillary artery where it bifurcated into two branches. An attempt has been made to dwell upon the embryological basis of the present anomaly. CONCLUSIONS: The relevance of anomalous arterial pattern of upper limb (U.L.) is realized while performing percutaneous arterial venous catheter insertion into subclavian vein via the infraclavicular route. We advocate a meticulous familiarization of the anatomy of axillary artery and its topographical relationship to other neurovascular structures for the operating plastic surgeon, anesthetist and radiologist (Fig. 1, Ref. 12).

The secretory clear cell of the eccrine sweat gland as the probable source of excess sweat production in hyperhidrosis.

Primary hyperhidrosis is characterized by excessive sweating in palmar, plantar and axillary body regions. Gland hypertrophy and the existence of a third type of sweat gland, the apoeccrine gland, with high fluid transporting capabilities have been suggested as possible causes. This study investigated whether sweat glands were hypertrophied in axillary hyperhidrotic patients and if mechanisms associated with fluid transport were found in all types of axillary sweat glands. The occurrence of apoeccrine sweat glands was also investigated. Axillary skin biopsies from control and hyperhidrosis patients were examined using immunohistochemistry, image analysis and immunofluorescence microscopy. Results showed that glands were not hypertrophied and that only the clear cells in the eccrine glands expressed proteins associated with fluid transport. There was no evidence of the presence of apoeccrine glands in the tissues investigated. Preliminary findings suggest the eccrine gland secretory clear cell as the main source of fluid transport in hyperhidrosis.

MRI of the axillary arch muscle: prevalence, anatomic relations, and potential consequences.

OBJECTIVE: The purpose of this study was to use MRI of the shoulder to analyze the axillary arch muscle and its anatomic relations to lymph nodes and the brachial plexus. MATERIALS AND METHODS: In this retrospective study at a single clinic, five observers blinded to the patient's condition assessed images from 1,109 consecutive initial shoulder MRI examinations for the presence and anatomic relations of the axillary arch. MRI interpretation reports were reviewed for documentation of previous injuries and upper extremity radicular pain or numbness for possible correlations between presence of the arch and symptoms of nerve entrapment. Results were reported as prevalence percentage or mean ± SD with 95% CI. Groups were compared by use of Student's t test or chi-square test as indicated (p < 0.05). RESULTS: An arch muscle was found in 71 of 1,109 (6%) examinations, and variability was found in arch insertion and visualization. A statistically significant 65 of 71 (92%) arches had a course superficial to the lymph nodes. The insertion of 50 of 71 (70%) arches was within 5 mm of the brachial neurovascular bundle. Excluding documented injuries, significantly more patients with an arch had upper extremity neurologic abnormalities than did patients without an arch (p = 0.02). CONCLUSION: The axillary arch muscle is situated in such a way that it can conceal lymph nodes and impinge on the brachial plexus, causing symptoms of upper extremity nerve entrapment. Radiologists' familiarity with the arch can improve their recognition of this muscular variant so that they can communicate appropriate clinical correlations to referring physicians.

The surgical importance of an axillary arch in sentinel node biopsy.

PURPOSE: When Carl Langer described the aberrant axillary arch in 1846 its relevance in sentinel node biopsy (SNB) surgery could not have been contemplated. The authors define an incidence and elucidate relevance of the arch in SNB of the axilla. METHODS: A review of a database for breast and melanoma axillary SNB was carried out. The sample was 1 year at Princess Margaret Hospital, Toronto. RESULTS: Of 319 axillary SNB, 3 (0.9%) had axillary arches noted. Two were in the melanoma group (n = 59) and one in the breast (n = 260). Interestingly one arch case had an ipsilateral 'idiopathic' axillary vein thrombosis as a child. CONCLUSIONS: The authors see no reason to deviate from the practice of division of the arch at the highest level when recognised at SNB. This would abrogate the risk of concealed nodes and possible future neurovascular compression.

Earwax, osmidrosis, and breast cancer: why does one SNP (538G>A) in the human ABC transporter ABCC11 gene determine earwax type?

One single-nucleotide polymorphism (SNP), 538G>A (Gly180Arg), in the ABCC11 gene determines the type of earwax. The G/G and G/A genotypes correspond to the wet type of earwax, whereas A/A corresponds to the dry type. Wide ethnic differences exist in the frequencies of those alleles, reflecting global migratory waves of the ancestors of humankind. We herein provide the evidence that this genetic polymorphism has an effect on the N-linked glycosylation of ABCC11, intracellular sorting, and proteasomal degradation of the variant protein. Immunohistochemical studies with cerumen gland-containing tissue specimens revealed that the ABCC11 WT protein was localized in intracellular granules and large vacuoles, as well as at the luminal membrane of secretory cells in the cerumen gland, whereas granular or vacuolar localization was not detected for the SNP (Arg180) variant. This SNP variant lacking N-linked glycosylation is recognized as a misfolded protein in the endoplasmic reticulum and readily undergoes ubiquitination and proteasomal degradation, which determines the dry type of earwax as a mendelian trait with a recessive phenotype. For rapid genetic diagnosis of axillary osmidrosis and potential risk of breast cancer, we developed specific primers for the SmartAmp method that enabled us to clinically genotype the ABCC11 gene within 30 min.

Transfer of pectoral nerves to suprascapular and axillary nerves: an anatomic feasibility study.

PURPOSE: We conducted an anatomic study to provide detailed information on the pectoral nerves and anatomic data on the transfer of the pectoral nerves to the axillary nerve. Moreover, we experimentally determined the feasibility of transferring the pectoral nerves to the suprascapular nerve in upper brachial plexus injury. METHODS: We dissected 26 brachial plexus from 15 fresh cadavers. The origin, location, course, and branching of the pectoral nerves were recorded. The length and the diameter of the pectoral nerves were measured. The diameter of the suprascapular and axillary nerves was recorded. In all dissections, we assessed the feasibility of directly transferring the pectoral nerves to the suprascapular and axillary nerves. RESULTS: We found 3 constant branches of pectoral nerves arising from 3 distinct origins in 20 cases, and 3 constant branches arising from 2 distinct origins in 6 cases. The C7 sent nerve fibers to all 3 branches. The average length and diameter of the superior, middle, and inferior branches of the pectoral nerves were 65 mm, 110 mm, and 105 mm, and 2.0 mm, 2.3 mm, ad 2.4 mm, respectively. The average diameter of the suprascapular and axillary were 2.8 mm and 3.6 mm, respectively. The superior branch reached the suprascapular and axillary nerves in 17 and 8 cases. The middle and inferior branches reached the suprascapular and axillary nerve in all dissections. CONCLUSIONS: With an adequate length, diameter, and nerve composition, the middle and inferior branches of the pectoral nerves are suitable donor nerves to the axillary nerve and a potential source of reinnervation of the suprascapular nerve in upper brachial plexus injury.

Anatomical basis for ultrasound-guided regional anaesthesia at the junction of the axilla and the upper arm.

PURPOSE: Ultrasound (US) has emerged in the field of regional anaesthesia in the past few years, as it allows physicians to simultaneously see the needle, the targeted nerves, and the vessels to avoid. Nevertheless, anatomical knowledge is essential for identifying all of the structures seen on the US screen. US also allows an in vivo approach to the variations of nerves and vessels. The aim of this study was to describe the anatomical structures of the axilla through a dissection, an anatomical section and US images performed during daily regional anaesthesia. This work will also discuss the usefulness of US in studying anatomical variations of vasculonervous structures. METHODS: The axillary region of an embalmed adult cadaver was dissected in the department of Anatomy, and anatomical sections of another embalmed and frozen cadaver were also performed. During the same period, fortuitous anatomical variations discovered during daily routine axillary US-guided nerve blocks were recorded in the department of Anaesthesiology. RESULTS: The anatomical dissection and sections allowed correlations to be made and structures to be identified on the US images. The most frequent anatomical variations found were double axillary artery, numerous axillary veins, variant location of the musculocutaneous nerve and posterior location of the brachial plexus in relation to the axillary artery. CONCLUSION: Anatomical knowledge is of major importance for US-guided regional anaesthesia. US scan offers a new approach to anatomical variations of the vasculonervous bundle at the junction of the axilla and the upper arm.

The axillary arch - morphological and histological study with clinical importance.

The latissimus dorsi is a muscle of the back which forms the posterior fold of the axilla and its tendon twists to insert into the floor of the intertubercular sulcus of the humerus. Occasionally, the muscle has a muscular slip which crosses the axilla to insert into the pectoralis major. This muscular slip is often termed as "axillary arch." In the present study, we report bilateral axillary arch detected in a 45-year-old male cadaver. The average vertical length of the axillary arch measured 7 cm. The average maximum width of the uppermost, middle and lower part of the arch measured 2, 3.5 and 3.2 cm, respectively. The presence of the axillary arch is an uncommon finding in humans, considering the fact that it is solely found in the animals who prefer to hang on the trees. A histological study of the axillary arch was also performed and it showed skeletal muscle fibres which was uniformly arranged. The presence of the axillary arch may assist in the adduction of the shoulder. It may also compress the axillary vessels and nerves thereby causing resultant symptoms. Prior anatomical knowledge of the presence of axillary arch may be helpful for surgeons performing radical dissection of the axillary lymph nodes and ligation of axillary vessels, clinicians diagnosing abduction syndromes and interventional radiologists interpreting axillary mass in day to day clinical practice.