Medial Cord Research Articles

Misexpression of Median Nerve Variation in Relation to 3rd Part of Axillary Artery – A Case Report

During a routine dissection of an adult male cadaver at the College of Medical Sciences in Bharatpur, Nepal, it was noted that the right median nerve was formed by three roots. This observation was made after a careful dissection of both upper limbs, including the axilla, arm, forearm, and palm. Of the three roots contributing to this anomalous median nerve, one originated from the lateral cord and two from the medial cord of the brachial plexus. Despite this atypical configuration, the distribution of the median nerve in the arm, forearm, and palm appeared normal, and the arterial pattern, including the axillary and brachial arteries, was also typical.

Variations of musculocutaneous nerve – A cadaveric study

Background: Musculocutaneous nerve (MCN) is a mixed nerve arising from the lateral cord of brachial plexus having root values C5, 6, and 7. It supplies the muscles of the flexor compartment of the arm namely; coracobrachialis, most part of brachialis and both heads of biceps brachii. It is cutaneous to the lower lateral part of forearm. Variations in the origin, course, branching pattern, termination, and connections of MCN are very common. Knowledge about these variations is important while evaluating unusual presentations of peripheral nerve injuries, during surgical procedures such as arthroscopy of shoulder joint, corrections of fracture humerus, brachial plexus block, and so on. Aims and Objectives: The study was conducted to find out any variations in the origin, course, branching pattern of the MCN. The secondary objective was to understand about the communication of the MCN with any other nerve. Materials and Methods: A descriptive study was conducted in 60 upper limb specimens dissected from 10% formalin embalmed 30 cadavers (adult) in the Department of Anatomy, Government Medical College, Kottayam. All limbs were carefully dissected and studied about the origin, course, termination, and variations of MCN. Results: Out of 60 specimens studied, in 46 specimens MCN Originate from lateral cord, eight from medial cord, and in six from the lateral root of the median nerve (MN). In 52 specimens, MCN supplies coracobrachialis but only in 34 it pierces this muscle. In four specimens, there is a communication between MCN and MN was seen. Conclusion: The MCN has significant variations and knowledge of these variations is clinically important in diagnosis and management of peripheral nerve injuries as well as surgical interventions in the arm.

Assessment of Upper Limb Nerves in Coronary Artery Disease Patients Undergoing Coronary Artery Bypass Graft.

Background Many patients experience pain in their upper limbs following surgical procedures involving median sternotomy, particularly those undergoing coronary artery bypass grafting (CABG). This type of pain, commonly reported by CABG patients, is often overlooked in hospital settings. Our study aims to address this issue by utilizing electrodiagnostic studies to understand this postoperative discomfort better. Objectives Cardiovascular procedures are standard and are trending toward endovascular interventions. Through this study, we aim to assess the occurrence of neurological issues in the upper limbs after CABGby comparing patients' preoperative and postoperative electrophysiological studies of the upper limb nerves. Materials and methods A prospective study was performed on 32 coronary artery disease (CAD) patients undergoing CABG to determine the effects of surgery on the upper limb nerves (median and ulnar nerves). We performed nerve conduction studies (NCS) and analyzed different parameters of both median and ulnar nerves pre and post-surgery. Results A change was noted in different NCS parameters of the median and ulnar nerves when we comparedthe pre and post-surgical values. The meanlatency of the median nerve sensory increased from a minimum of 3.01 millisecondsat the preoperative level to a maximum of 3.60 milliseconds when assessedtwo weeks post-surgery. The mean amplitude decreased from 16.49 microvolts to a minimum of 12.30 microvolts when assessed two weeks post-surgery. The meanvelocity decreased from 55.83 m/s at the preoperative value to a minimum of 45.03 m/sat the two weeks post-surgery assessment. The ulnar nerve also underwent similar changes. Conclusion The observed changes in latency, amplitude, and velocity might be attributed to various factors, including surgical trauma, inflammation, or alterations in the physiological state post-surgery. The sternotomy technique and the position and extent of opening the sternal retractor determine the prevalence of complications by causing injury to the medial and lateral cords of the brachial plexusafter CABG. Careful preoperative and postoperative assessments of patients may aid in preventing, minimizing, and treating these often undiagnosed complications.

Clinico-anatomical insight into the unusual course, branching pattern and connections of ulnar nerve: A narrative review.

Ulnar nerve originates from the lower trunk as a branch from anterior division, continuing as a branch from medial cord of the brachial plexus. It receives fibres from anterior rami of cervical nerve root 8 and the first thoracic nerve root. Ulnar nerve injury accounts for being the most common vessel of upper limb that results in hospitalisation. Knowing the variability in the anatomical pattern of ulnar nerve and its communication with various branches of nerves in the vicinity can have implications. The current narrative review comprised literature search on Google, Google Scholar and PubMed databases for articles published between 2015 and 2023 on the subject. The insight and understanding of the related ulnar nerve anatomy is likely to be of prodigious help to anatomists, surgeons, physicians and radiologists in preventing unexpected outcomes in the future.

The axillary artery high bifurcation: coexisting variants and clinical significance.

Several branching patterns of the axillary artery (AA) have been described. Unusually, the brachial artery (BA) follows a course in front of the median nerve (MN), the so-called superficial brachial artery (SBA). The SBA may result in MN entrapment. The current cadaveric report highlights a high AA bifurcation, its continuation as SBA and the coexistence of muscular, neural, and vascular asymmetric aberrations. At the right side, the coracobrachialis muscle (CB) had a single head, and the ipsilateral musculocutaneous nerve (MCN) followed a medial course. The AA was highly divided into superficial and deep stems (SAS and DAS), at the 2nd rib lower border. Between two stems, the brachial plexus (BP) lateral and medial cords were identified. The MN originated from the BP lateral cord. The SAS, continued as SBA with a tortuous course. The DAS coursed posterior to the BP medial and lateral cords and gave off the subscapular artery. A bilateral 3rd head of the biceps brachii was identified. The MN atypically originated from the BP lateral cord. At the left side, the two-headed CB was typically penetrated by the MCN. A common trunk of the circumflex humeral arteries was identified in coexistence with an interconnection of the BP lateral cord with the MN medial root. The rare coexistence of muscular, neural, and arterial variants in axillary and brachial region is emphasized, taking into consideration the AA high division and related branching pattern. Documentation of such rare vascular variants is important in aneurysm and trauma surgery, and angiography, where all therapeutic manipulations must be accurately performed due to the possibility of complications.

Costoclavicular block – single to double injection – time to see the premiere of triple injection

Sir,Securing the phrenic nerve when achieving effective anesthesia block for the upper limb has been a topic intriguing regional anesthesia enthusiasts ever since. Interscalene brachial plexus block is known to involve the phrenic nerve in 100% of the cases and costoclavicular block which has gained momentum since 2015 is declared to involve the phrenic nerve in 0% of the cases. Besides this the compact, reliable topography of the cords in the triangular costoclavicular space along with an expedited sensorimotor block with local anesthesia deposited in the center of the three cords makes costoclavicular block an attractive option for elbow and below elbow surgeries. According to the studies, the success rate of the blockade is 92.5% with single injection in the center of the cords. Another study by Sebastian, where apart from classical single injection, another injection was given after redirecting the needle, between the medial cord and subclavian artery (labeling it a corner pocket technique) for costoclavicular block. They concluded that the block’s onset time and total anesthesia-related time were significantly shortened with the double injection technique compared with single injection. The basis of this was explanation laid by Dr. Monzo and Hadzic where they proposed in a series of 40 patients a linear septum arising from the lateral part of axillary artery separating the lateral code from the posterior and the medial code, thus compartmentalizing the costoclavicular space. They reported a success rate of 97.5% in their study on 40 patients.4 Hence,double injection is used to overcome the septum “issue.” Pornpatra is defined a high definition ultrasonographic presence of paraneural sheath and facial compartments surrounding the brachial plexus cords at the lateral infraclavicular fossa and the costoclavicular space. We propose that a triple injection with 3rd injection in the vicinity of the lateral cord just before withdrawing the needle apart from the other two injections significantly shortens the onset time of sensory block from 16 min to 9 min. The various sites for injection are shown in the figure below, but the exact point of injection of the second and third is more prominent after giving the first injection. The chances of the median nerve sparing as has been reported in some cases in previous studies are almost nil by this technique - the corner pocket injection that involves the medial root of the median nerve and the lateral cord that is specifically blocked separately covering the lateral root of the median nerve. CONCLUSIONWe did a case series in 15 cases and although the sample size is small and this is definitely not a randomized control trial, to make such a bold statement, we would like to decipher a positive future of the costoclavicular block with triple injection technique with an RCT already underway.

Abnormal Innervation of the Arm Muscles by the Median Nerve: A Case Report

Introduction: Brachial plexus variations have been observed in some people. The median nerve is one of the branches of this plexus, formed by the union of the medial and lateral cords. The median nerve usually does not have a branch in the arm region and innervates the forearm and hand muscles. Case Presentation: During the dissection of the right axillary cavity of a 74-year-old male donor for medical students, the variation in the innervation of arm muscles was observed. Unexpectedly, the biceps brachii and brachialis muscles were innervated by the branches of the median nerve. The median nerve normally does not have a branch in the arm region and innervates the forearm and hand muscles. The musculocutaneous nerve (C5-7) is a terminal branch of the lateral cord and innervates the three muscles of the anterior compartment of the arm, namely coracobrachialis, biceps brachii, and brachialis muscles. Conclusions: The innervation of the arm's anterior compartment muscles by the median nerve is a rare variation that has never been seen in this country. Awareness of such anatomical variations is necessary for physicians and clinicians. These variations should be taken into consideration during axillary region surgeries.

A Case Report of a Rare Variation of the Medial Cutaneous Nerve of Forearm

Introduction: The brachial plexus is the largest and most complex nerve network in the body, which is formed in the neck and enters the axillary cavity after passing under the clavicle. So far, many variations have been reported in the brachial network, which are clinically important. The plexus has three cords, one of which is the medial cord. The medial cutaneous nerve of the arm and the medial cutaneous nerve of the forearm are the branches of the medial cord that innervate the skin of the medial surface of the arm and forearm, respectively. In this study, a rare variation was observed in the branches of the medial cord of the brachial plexus during the dissection of the upper limb of an approximately 80-year-old man in the Dissection Hall of Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Thus, in normal condition, there is no connection between the medial cutaneous nerve of the arm and the medial cutaneous nerve of the forearm, and each of them innervates the skin of the medial arm and forearm separately, but in this case, these two nerves are connected. And since knowing this type of variation is very important for surgeons, more studies are needed to determine its prevalence in the population.

A Cadaveric Study to Define the Variant Patterns of Median Nerve Formation.

The median nerve is one of the important nerves of the upper limb which supplies the muscles of the front of the forearm,muscles of the hand, and skin of the hand. Many works of literature mentioned its formation by the fusion of two roots, the medial root from the medial cord and the lateral root from the lateral cord. But multiple variations in the median nerve formation have clinical importance from surgical and anesthetic points of view. For the study purpose, we dissected 68 axillae of 34 formalin-fixed cadavers. Out of 68 axillae, two (2.9%) showed median nerve formation by a single root, 19 (27.9%) showed median nerve formation by three roots, and three (4.4%) showed median nerve formation by four roots. A normal pattern of median nerve formation by fusion of two roots was seen in 44 (64.7%)axilla. The knowledge of variant patterns of median nerve formation will be helpful to surgeons and anesthetists while performing surgical or anesthetic procedures in the axilla to avoid any injury to the median nerve.

An unusual combination of a bilateral aberrant suprascapular artery with neurovascular structures variants

PurposeThe report describes a bilateral suprascapular artery (SPSA) of atypical origin in coexistence with neurovascular aberrant structures.MethodsThe variants were identified in a 91-year-old formalin-embalmed male cadaver, derived from a body donation program after a signed informed consent.ResultsThe left-sided SPSA emanated from the 1st part of the axillary artery, coursed between the brachial plexus lateral and medial cords, accompanied by the suprascapular nerve, and passed below the superior transverse scapular ligament. Ipsilateral coexisted variants were the lateral thoracic artery multiplication, the subscapular trunk formation, and the musculocutaneous nerve duplication. In the right supraclavicular area, a SPSA duplication was identified. The main artery emanated from the thyrocervical trunk in common with the transverse cervical artery and the accessory SPSA emanated from the dorsal scapular artery. Both SPSAs coursed over the superior transverse scapular ligament, while the suprascapular nerve ran below the ligament.ConclusionsThe current study reported a bilateral aberrant SPSA, originating from the AA 1st part (left side) and from the dorsal scapular artery (right side), which coexisted with adjacent neurovascular structures’ variants. The left SPSA atypically coursed below the superior transverse scapular ligament. Such an unusual combination of variations, present bilaterally in the current study, may be challenging for radiologists and surgeons.

Aberrant brachial artery: case report of an anatomical variation

INTRODUCTION: The brachial artery and its terminal branches are the major arterial supply to the brachium and antebrachium. Variations in the vascular supply in the upper limbs have been previously documented to occur more in the radial artery, followed by the ulnar artery, but less commonly in the brachial arteryCASE: An embalmed cadaver was used for gross dissection during the gross anatomy dissection for postgraduate students at the department of human anatomy of the University of Rwanda.During the dissection of the right upper arm, an accessory brachial artery was found, branching from the axillary artery above the unification of the lateral and medial cords of the brachial plexus (the lateral and medial root of the median nerve).CONCLUSION: In our case, the aberrant brachial artery originated from the axillary artery and gave off a muscular branch in the middle third of the arm, which is of clinical importance.

Clinically Relevant Anatomical Variations in the Brachial Plexus.

Anatomical variation in the brachial plexus may result in a variety of clinically relevant patterns, including various neuralgias of the upper extremity and differing nerve territories. Some conditions can be debilitating in symptomatic patients, resulting in paresthesia, anesthesia, or weakness of the upper extremity. Others may simply result in cutaneous nerve territories that deviate from a traditional dermatome map. This study evaluated the frequency and anatomical presentations of a large number of clinically relevant brachial plexus nerve variations in a sample of human body donors. We identified a high frequency of various branching variants, of which clinicians, especially surgeons, should be aware. The medial pectoral nerves in 30% of the sample were found to originate from either the lateral cord, or both the medial and lateral cords of the brachial plexus rather than exclusively from the medial cord. The dual cord innervation pattern greatly increases the number of spinal cord levels traditionally believed to innervate the pectoralis minor muscle. The thoracodorsal nerve arose as a branch of the axillary nerve 17% of the time. The musculocutaneous nerve sent branches to the median nerve in 5% of specimens. The medial antebrachial cutaneous nerve shared a common trunk with the medial brachial cutaneous nerve in 5% of individuals and derived from the ulnar nerve in 3% of specimens.

Morphological significance of the medial brachial cutaneous nerve: An anatomical study of the brachial plexus in primates.

The medial brachial cutaneous nerve (MBC) originates from the medial cord of the brachial plexus and innervates the skin sensory in the medial posterior surface of the upper arm. Considering previous reports of the primate brachial plexus, the MBC appeared to be the sole branch in the brachial plexus that only some primates possess. However, the detailed descriptions and records regarding the morphology of the MBC and related nerves, their origins and distributions (dermatomes) in particular, were frequently lacked in the previous reports, and it remains unclear why the difference in the MBC appearance exists among primates. In this study, the brachial plexus and its branches were first re-evaluated and certainly identified in several primates, humans, chimpanzee, macaque monkey, lutung, tamarin, squirrel monkey, and spider monkey. The MBC was identified in humans, chimpanzee, spider monkey, and squirrel monkey. In the other species, the intercostobrachial nerve (ICB) originating from some of 1st to 3rd intercostal nerves developed and distributed instead of the MBC. According to the kinesiological and behavioral studies, the former species possessing MBC show high shoulder joint mobility associated with their locomotive patterns. We speculate that the MBC corresponds to transformed ICB; specifically, where it originates presumably transfers from the 1st and/or 2nd intercostal nerves to the brachial plexus, which allows it to reach the upper arm by coursing the shortest distance even if the forelimb is raised high. Therefore, MBC may embody phylogenetic morphogenesis of the nerve associated with the locomotive evolution and adaptation in primate forelimb.

Persistent and profound peripheral nerve injuries following reverse total shoulder arthroplasty

Peripheral nerve injuries associated with reverse total shoulder arthroplasty (rTSA) are rarely reported and are often dismissed as neuropraxias, particularly in the setting of perioperative nerve blocks. The purpose of this study was to evaluate nerve injuries following rTSA to determine if there is a pattern of injury and to evaluate outcomes of patients who sustain an intraoperative nerve injury. A retrospective review was performed identifying patients who underwent rTSA and had a concomitant major nerve injury who were referred to a multidisciplinary peripheral nerve injury clinic. Demographic data, preoperative nerve block use, physical examination, electrodiagnostic studies, injury pattern, and time from injury to referral was collected. Radiographs, Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH) score, and outcomes surveys were obtained at final follow-up. Twenty-two patients were identified with postoperative nerve injuries. Average time from injury to referral was 9.0 months, with 18.8 months' follow-up. Eight patients had undergone prior shoulder surgery, and 11 patients had prior shoulder trauma. Injury patterns were variable and involved diffuse pan-plexopathies with severity localized to the posterior and medial cords (11), the upper trunk (5), lateral cord (2), and axillary nerve (4). The average postoperative acromiohumeral distance (AHD) was 3.7 cm, with an average change of 2.9 cm. The average postoperative lateral humeral offset (LHO) was 1.1 cm, with an average change of 0.2 cm. Seventeen patients were confirmed to have undergone preoperative nerve blocks, which were initially attributed as the etiology of nerve injury. Eighteen patients were initially treated with observation: 11 experienced residual debilitating neuropathic pain and/or disability, and 7 had substantial improvement. One patient underwent nerve transfers, whereas the others underwent procedures for hand dysfunction improvement. The average QuickDASH score was 53.5 at average of 4 years post rTSA. Although uncommon, permanent peripheral nerve injuries following rTSA do occur with debilitating effects. Preoperative regional blocks were used in most cases, but none of the blocks could be directly attributed to the nerve injuries. Nerve injuries were likely secondary to traction at the time of arthroplasty and/or substantial distalization and lateralization of the implants. Patients with medial cord injuries had the most debilitating loss of hand function. Surgeons should be cognizant of these injuries and make a timely referral to a peripheral nerve specialist.

The reanimation of the elbow functions in avulsive injuries of the upper brachial plexus using the medial cord transfer: nuances of the technique and update

ABSTRACT Objectives Report on a new transfer for the reinnervation of biceps and brachialis muscles after multilevel avulsive injuries of brachial plexus provided at least T1 is viable: the Medial Cord to Musculocutaneous (MCMc) and its variant, the Medial Cord to anterior Upper Trunk (MC-aUT). The MC-aUT is indicated in agenesia of musculocutaneous nerve and when a residual function in the biceps is present. The MCMc transfer would be unfeasible in the former and contraindicated in the latter. Methods Three hundred and five consecutive patients, classified according to the quality of hand function, are available for a long-term follow-up after reconstructive surgery. They had multiple cervical root avulsive injuries at two (C5-C6), three (C5-C6-C7) and four (C5-C6-C7-C8) levels. The reinnervation was obtained via an end-to-end transfer from two donor fascicles located in the medial cord (MC) and aimed at the flexor carpi ulnaris or the flexor digitorum profundus. Results These transfers have no failures and no complications when the hand shows a normal function. In the case of suboptimal conditions of the hand, the technique is more challenging, but still has many satisfactory results. In the four-root avulsive injuries, on the contrary, strong limitations suggest that different strategies should be preferred. EMG shows a reinnervation in both biceps and brachialis muscles and this accounts for the quality of results. Tendon transfers for wrist and finger dorsiflexion, when required, remain unencumbered. Discussion The procedures are safe, effective and easily feasible. The ideal candidate has a C5-C6 injury and a normal hand function.

A meta-analysis on the anatomical variability of the brachial plexus: Part III – Branching of the infraclavicular part

IntroductionThe anatomy of the brachial plexus has been a subject of interest to many researchers over time resulting in an inconsistent amount of data. Previously, our team had published two evidence-based studies on the anatomical variations involving the brachial plexus, therefore the aim of this study was to analyze the findings regarding the infraclavicular part of the brachial plexus with the use of meta-analytic techniques to complete the comprehensive series. Material and methodsMajor scientific databases were extensively searched to compile anatomical studies investigating the morphology of the infraclavicular part of the brachial plexus. Extracted data were classified based on our proposed classification system and subsequently analyzed with the use of random effects meta-analysis to state the pooled prevalence estimates of the distinct variation patterns. ResultsA total of 75 studies (4772 upper limbs) were selected for the meta-analysis. The branches of the lateral cord, including the lateral pectoral nerve and musculocutaneous nerve, resembled their usual origin in 76.8% (95% CI 50–96%) and 98.8% (95% CI 98–100%), respectively. The medial pectoral nerve, medial brachial cutaneous nerves, medial antebrachial cutaneous nerve and ulnar nerve emerging from the medial cord were observed originating from their usual origins in 90.9% (95% CI 68–100%), 90.7% (95% CI 73–100%), 87.9% (95% CI 67–99%) and 97.7% (95% CI 94–100%), respectively. Lastly, nerves branching from the posterior cord, including the superior and inferior subscapular nerves, thoracodorsal nerve, axillary nerve and radial nerve, originated as per textbook description in 90.7% (95% CI 80–98%), 76.1% (95% CI 61–89%), 90.1% (95% CI 84–95%), 79.8% (95% CI 68–90%) and 99.0% (95% CI 96–100%), respectively. Moreover, the usual origin of the median nerve from the lateral and medial cord via the corresponding roots was encountered in 89.7% (95% CI 84–95%) of cases. ConclusionsThe nerves originating from the infraclavicular part of the brachial plexus exhibit a wide spectrum of possible origins. However, the usual patterns were significantly the most common types present in more than three quarters of cases. Especially clinicians might profit from the enhanced understanding of the brachial plexus anatomy presented herein, since we offer a strong guide for handling the anatomically challenging pathologies in this specific area.

Ultrasound-guided single needle tip placement below axillary artery in the infraclavicular area: A cadaveric study.

The parasagittal ultrasound-guided infraclavicular block (ICB) aims to cover all the elements of brachial plexus for the surgeries at and below the elbow. Our aim was to demonstrate the spread of 20 ml latex in vicinity of brachial plexus cords after injecting posterior to the axillary artery in Thiel embalmed cadavers. A blunt insulated needle was inserted posterior to the axillary artery in a traditional parasagittal infraclavicular in 2 Thiel embalmed cadavers, on both the sides (four specimens). A day later cadaver 1 was dissected and cadaver 2 was frozen at ‒20ºC for 2 weeks and sectioned. Both cadavers were photographed. In cadaver 1, dissection revealed a spread of red latex on the lateral cord extending onto the musculocutaneous nerve, the posterior cord engulfing the radial and axillary nerves distally. In cadaver 2, a cross-section revealed latex engulfed all three cords. Single injection of 20 ml latex aimed posterior to the axillary artery in the parasagittal infraclavicular approach engulfed the posterior, medial and lateral cord in Thiel embalmed cadavers. This needs to be investigated in patients who receive ICB clinically and using contrast studies.

Anatomical variation of median nerve: cadaveric study in brachial plexus.

Median nerve is formed by lateral root from lateral cord and medial root from medial cord of brachial plexus. Formation of median nerve occur in front or lateral to axillary artery in axilla. In the present study we observed anatomical variations of median nerve formation in the brachial plexus. We examined formalin fixed 60 upper limbs from 30 adult cadavers (15 males and 15 females) which were above the age 40 years from the department of Anatomy. All the cadavers were dissected on both sides according to Cunningham’s Manual of Practical Anatomy. Normal formation of median nerve by two roots noted in 42 (70.0%) of upper limb specimen. Variation of median nerve formation noted in 18 (30.0%) upper limb specimen. Three roots taking part in the formation of median nerve in 13 (21.7%) upper limb specimen where additional root coming from lateral cord of brachial plexus. Four roots taking part in formation of median nerve in 3 (5.0%) upper limb specimen, where additional roots coming from lateral cord and posterior cord of brachial plexus. Lateral root crossed the axillary artery anteriorly to join with medial root lying medial to axillary artery. The median nerve formed medial to third part of axillary artery. Additional communication with musculocutaneous nerve with median nerve seen in 2 (3.3%) upper limb specimen. Knowledge of such anatomical variations is of interest to the anatomist and clinician alike. Surgeons who perform procedures involving neoplasm or repairing trauma need to be aware of these variations. Median nerve variation may lead to confusions in surgical procedures and axillary brachial plexus nerve block anesthesia.

The ulnar nerve in the cubital tunnel: a foetal study.

The ulnar nerve (UN), a terminal branch of the medial cord of the brachial plexus, is located posteromedial to brachial artery coursing along medially in the arm from the anterior to the posterior compartment through the arcade of Struthers. It passes posterior to medial epicondyle of humerus and enters the cubital tunnel. Then, it exits through the distal part of the cubital fossa to enter the medial side of the forearm between the two heads of the flexor carpi ulnaris muscle underneath Osborne's ligament to enter the anterior compartment of the forearm. Entrapment of the UN at the cubital tunnel results in a pain and a tingling sensation on the medial side of the forearm and fourth and fifth digits. This foetal study documented the course of the UN within the cubital tunnel and its anatomical relations utilising bilateral microscopic dissection of 25 foetuses (gestational age: 19-36 weeks). The UN followed the standard anatomical course in 96% (48/50) of the specimens, however it was found to lie deep to the muscles of the cubital tunnel in 6% (3/50). The radial artery joined the UN distal to the cubital tunnel in 8% (4/50), while the superior ulnar collateral artery was posteriorly related to the UN in 32% (16/50) of specimens. The Osborne's ligament (crossed between the two heads of the flexor carpi ulnaris muscle, posterior to the medial epicondyle of the humerus) was present in all specimens 100% (50/50). It had a mean length of 6.32 ± 0.97 mm and 6.30 ± 1.10 mm on the left and right sides, respectively. The current study observed that the flexor pronator aponeurosis was present in 2% (1/50) of specimens. Knowledge of the normal and variable anatomical course of the UN in the cubital tunnel in this study may assist in the diagnosis and treatment of compressive neuropathy of the UN in the cubital tunnel.

Pre-injection technique to identify neural elements in the costoclavicular space for brachial plexus block: Where and what to inject?

Sir, We read with interest the captioned letter “Use of a pre-injection technique to identify neural elements in the costoclavicular space for brachial plexus block for upper limb orthopaedic surgery”.[1] We appreciate the authors’ idea of a pre-injection technique to identify the neural elements in the costoclavicular space (CCS), but have few suggestions. The authors have chosen the supraclavicular fossa as their pre-injection site and administered 3 ml of local anaesthetic (LA) with the assumption that it would reach the CCS. However, one should keep in mind that even a small LA volume of 5 ml at the supraclavicular fossa may be associated with hemidiaphragmatic paralysis (HDP).[2] Therefore, we rather recommend a hydro-dissection technique using 0.9% saline at the CCS. In this method, as the needle passes the subclavius muscle and approaches the brachial plexus sheath (paraneural sheath),[3] small aliquots of 1-2 ml of 0.9% saline will be injected [Figure 1a] to appreciate if the injection is intramuscular or just outside the epimysium of the subclavius muscle/paraneural sheath. Once confirmed, the block needle is gently advanced into the paraneural sheath between the lateral and posterior cords [Figure 1b] and a second injection of saline will now separate the tightly clustered cords. This helps to delineate the neural components.Figure 1: (a) Schematic diagram demonstrating hydro-dissection technique with needle tip just outside the subclavius muscle and the brachial plexus sheath at the costoclavicular space (CCS); (b) Schematic diagram demonstrating block needle inside the brachial plexus sheath at the gap/fissure between the lateral and posterior cord of the brachial plexus sheath at the CCS. AA: Axillary artery (1st part); AV: Axillary vein; LC: Lateral cord; MC: Medial cord; PC: Posterior cord; Blue coloured arrows demonstrating the brachial plexus or paraneural sheath around the cords of the brachial plexus at the CCS. Black star (*) demonstrating the gap/fissure between the lateral and posterior cord of the brachial plexus after the saline hydro-dissection techniqueThis hydro-dissection technique is simple, effective, carries no additional risks for HDP and does not require two separate injections. Hence, we recommend it over the pre-injection technique described by the authors at the supraclavicular fossa for identifying the neural elements in the CCS. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.