Ultrasound-guided ventral approach to the brachial plexus block in barred owls (Strix varia): a cadaveric study.

OBJECTIVE: To develop an ultrasound (US)-guided ventral approach to the brachial plexus (BP) and evaluate nerve anatomy and staining in barred owl cadavers. STUDY DESIGN: Prospective, cadaveric study. ANIMALS: Eleven adult male and female barred owl cadavers with a body mass of 0.43-0.98 kg. METHODS: Eleven frozen cadavers were thawed for 48 hours, weighed and assigned a body condition score. Ten cadavers were placed in dorsal recumbency with wings abducted. US-guided visualization of the BP was achieved by placing a 13-6 MHz linear probe over the ventral aspect of the scapulohumeral joint, parallel to the sternum. A 22 gauge, 50 mm insulated needle was advanced in-plane in a caudal-to-cranial direction. In each owl, injection targeting one BP was performed with 0.4 mL kg-1 of a 1:1 0.5% ropivacaine and 1% methylene blue solution. Dissection was performed 15 minutes postinjection. Nerve staining was deemed successful if ≥ 1 cm of circumferential staining was achieved. The eleventh owl cadaver was injected with a 1:1 solution of 1% methylene blue and 74% ioversol contrast into both wings, and computed tomography (CT) was performed just before and 15 minutes after injection. RESULTS: The BP was clearly identified ultrasonographically in cadavers weighing > 0.5 kg. An injectate volume of 0.4 mL kg-1 provided complete staining of the BP branches in all cadavers. CT scan revealed no contrast within the coelomic cavity. CONCLUSIONS AND CLINICAL RELEVANCE: The US-guided BP injection using a ventral approach was easily performed in barred owl cadavers weighing > 0.5 kg. The injection of 0.4 mL kg-1 of a ropivacaine-dye solution resulted in complete staining of the BP branches in all wings, suggesting that this technique could provide analgesia for structures distal to the scapulohumeral joint. Clinical studies are necessary to confirm the safety and efficacy of this technique in barred owls and other bird species.

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.

Origin and distribution of the brachial plexus in red-necked wallaby (Notamacropus rufogriseus, Marsupialia: Macropodidae).

Notamacropus rufogriseus (red-necked wallaby) are in the family Macropodidae, which is the second largest family of marsupials after the family Didelphidae. This study was conducted with the aim of providing a detailed description of the origin and distribution of the brachial plexus in N. rufogriseus. Two-year-old male and 3-year-old female red-necked wallabies were used for the study. The brachial plexus was formed by ventral rami of C4, C5, C6, C7, C8, and T1 spinal nerves. It is composed of three trunks that give rise to 12 principal nerves. The cranial trunk is formed by the combination of the rami C4-C7; the middle trunk is formed by the combination of the rami C6 and C7; and the caudal trunk is formed by the combination of the rami C8 and T1. Differences between left and right side of the plexus brachialis were not observed. C6 ventral spinal rami contribute the most to brachial plexus nerve formation, while C4 contributes the least. The formation and distribution of the plexus in N. rufogriseus exhibited more resemblance to the patterns observed in marsupial animals rather than placental mammals. Marsupial mammals demonstrate the involvement of C4 in the development of the brachial plexus. The formation and branching of the brachial plexus sequentially adapt in accordance with changes in their thoracic limb activities and innervation points. Anatomical data from brachial plexus studies optimizes thoracic limb clinical and surgical treatments. This work can provide baseline data for future marsupial brachial plexus studies and fill gaps in the scarce literature.

A Prefixed Four-Trunk Brachial Plexus with Anomalous Anatomy of All Subsequent Divisions, Cords, and Terminal Branches: A Cadaveric Case Report.

BACKGROUND The brachial plexus is a complex neural structure providing motor and sensory innervation to structures of the arm, shoulder, and upper chest. The anatomical structure is typically divided into roots, trunks, divisions, and cords. Due to the presence of multiple nerve roots and branches, anatomical variations are common. Awareness of variations from normal anatomy is important in imaging, administration of nerve blocks, and surgical procedures of the neck and shoulder region. CASE REPORT We present a case of multiple anatomic variations of the right brachial plexus identified in a cadaver during routine dissection. To summarize, we identified a prefixed plexus with anomalous contributions from the C4 nerve root. Nerve roots C4 and C5 emerged anterior to the anterior scalene muscle. Furthermore, 4 trunks, rather than the typical 3, gave rise to multiple anomalies in the branching pattern of the distal divisions and cords. To the best of our knowledge, this is the first such case reported in the published literature. CONCLUSIONS The current case report presents a combination of brachial plexus anomalies not previously described in the medical literature - specifically, a prefixed (C4-T1) brachial plexus positioned anterior to the anterior scalene muscle with anomalies of the trunks, divisions, cords, and terminal branches. The variations presented have implications in neurogenic compression, interscalene blocks, and trauma to the upper limb. Knowledge of these anomalies may better equip anatomists and clinicians to understand pathology and intervention of the upper limb.

Anatomical variations of the brachial plexus in adult cadavers: A descriptive study and clinical significance.

BACKGROUND: Brachial plexus injury is recognized as one of the most severe clinical challenges due to the complex anatomical configuration of the brachial plexus and its propensity for variation, which complicates safe clinical interventions. This study aimed to ascertain the prevalence and characterize the types of brachial plexus variations, and to elucidate their clinical implications. MATERIALS AND METHODS: We conducted meticulous dissections of 60 formalin-fixed cadavers' upper arm, axilla and lower neck to reveal and assess the roots, trunks, divisions, cords, and branches of the brachial plexus. The pattern of branching was noted by groups of dissecting medical students and confirmed by the senior anatomists. The variations discovered were record and photographed using a digital camera for further analysis. RESULTS: Variations in the brachial plexus were identified in 40 of the 60 cadavers, yielding a prevalence rate of 66.7%. These variations were classified into root anomalies (2.1%), trunk anomalies (8.5%), division anomalies (2.1%), and cord anomalies (4.3%). Notably, anomalies in communicating branches were observed in 39 cadavers (83.0%): 14 with bilateral anomalies, 14 with anomalies on the left side, and 11 on the right side. These communicating branches formed connections between the roots and other segments, including trunks, cords, and terminal nerves, and involved the median, musculocutaneous, and ulnar nerves. CONCLUSION: The frequency and diversity of brachial plexus variations, particularly in communicating branches, are significant in cadavers. It is imperative that these variations are carefully considered during the diagnostic process, treatment planning, and prior to procedures such as supraclavicular brachial plexus blocks and nerve transfers, to mitigate the risk of iatrogenic complications.

An unusual relationship between the axillary artery and brachial plexus in a cross-breed dog cadaver: a proposal for revising the terminology for nerve loops.

In the left axilla of a formalin-embalmed adult female cross-breed dog, an unusual course of the axillary artery in relation to the brachial plexus was noted. A part of the axillary artery after the origin of the subscapular artery coursed through the loop formed by the contributions of the caudal pectoral and lateral thoracic nerves and then between the median and ulnar nerves. Thus, the common trunk for the latter two nerves was missing. Instead, in the proximal brachium, they communicated with each other in both directions. A communicating branch between the cranial and caudal pectoral nerves forming a nerve loop, ansa pectoralis lacked the axillary artery and was instead traversed by the subscapular artery. This is a variation in the relationship between the axillary artery and brachial plexus in the domestic dog and has not been reported in the literature yet. The axillary artery entrapped by the contributions of the caudal and lateral thoracic nerves may be considered as a risk factor for the neuroarterial compressions with non-specific signs and should be taken into account both in surgery and imaging.

Investigating the effect of anatomical variations in the response of the neonatal brachial plexus to applied force: Use of a two-dimensional finite element model.

The brachial plexus is a set of nerves that innervate the upper extremity and may become injured during the birthing process through an injury known as Neonatal Brachial Plexus Palsy. Studying the mechanisms of these injuries on infant cadavers is challenging due to the justifiable sensitivity surrounding testing. Thus, these specimens are generally unavailable to be used to investigate variations in brachial plexus injury mechanisms. Finite Element Models are an alternative way to investigate the response of the neonatal brachial plexus to loading. Finite Element Models allow a virtual representation of the neonatal brachial plexus to be developed and analyzed with dimensions and mechanical properties determined from experimental studies. Using ABAQUS software, a two-dimensional brachial plexus model was created to analyze how stresses and strains develop within the brachial plexus. The main objectives of this study were (1) to develop a model of the brachial plexus and validate it against previous literature, and (2) to analyze the effect of stress on the nerve roots based on variations in the angles between the nerve roots and the spinal cord. The predicted stress for C5 and C6 was calculated as 0.246 MPa and 0.250 MPa, respectively. C5 and C6 nerve roots experience the highest stress and the largest displacement in comparison to the lower nerve roots, which correlates with clinical patterns of injury. Even small (+/- 3 and 6 degrees) variations in nerve root angle significantly impacted the stress at the proximal nerve root. This model is the first step towards developing a complete three-dimensional model of the neonatal brachial plexus to provide the opportunity to more accurately assess the effect of the birth process on the stretch within the brachial plexus and the impact of biological variations in structure and properties on the risk of Neonatal Brachial Plexus Palsy.

Rare case of divided phrenic nerve variation: a cadaveric case report.

The phrenic nerve innervates the respiratory diaphragm, the primary muscle active during ventilation. The canonical path of the phrenic nerve originates from the cervical spine at C3-C5 spinal nerves and travels inferiorly through the neck and thoracic cavity to reach the diaphragm. During a cadaver dissection, a variation of the phrenic nerve was discovered in a 93-year-old male specimen. A traditional origin of the phrenic nerve was noted; however, the nerve branched into medial and lateral components at the level of the superior trunk of the brachial plexus. The branches reconnected at the apex of the aortic arch and continued inferiorly to innervate the ipsilateral diaphragm. This case study describes a rare type of branching of the phrenic nerve and explores its potential impact on clinical procedures.

Optimising safe margins in shoulder surgeries: a cadaveric study on brachial plexus nerves with anthropometric and movement correlation.

PURPOSE: Shoulder surgeries, vital for diverse pathologies, pose a risk of iatrogenic nerve damage. Existing literature lacks diverse bone landmark-specific nerve position data. The purpose of this study is to address this gap by investigating such relationships. METHOD: This cadaveric study examines axillary, radial and suprascapular nerves' relation with acromion, coracoid and greater tuberosity of the humerus (GT). It also correlates this data with humeral lengths and explores nerve dynamics in relation to arm positions. RESULTS: The mean distance from the axillary nerve to (i) GT was 4.38 cm (range 3.32-5.44, SD 0.53), (ii) acromion was 6.42 cm (range 5.03-7.8, SD 0.694) and (iii) coracoid process was 4.3 cm (range 2.76-5.84, SD 0.769). Abduction brought the nerve closer by 0.36 cm, 0.35 cm and 0.53 cm, respectively. The mean distance from radial nerve to (i) GT was 5.46 cm (range 3.78-7.14, SD 0.839), (ii) acromion was 7.82 cm (range 5.4-10.24, SD 1.21) and (iii) tip of the coracoid process was 6.09 cm (range 4.07-8.11 cm, SD 1.01). The mean distance from the suprascapular nerve to the acromion was 4.2 cm (range 3.1-5.4, SD 0.575). The mean humeral length was noted to be 27.83 cm (range 25.3-30.7, SD 1.13). There was no significant correlation between these distances and humeral lengths. CONCLUSION: It is essential to exercise caution to avoid axillary nerve damage during the abduction manoeuvre, as its distance from the greater tuberosity and tip of the coracoid process has shown a significant reduction. The safe margins, in relation to the length of the humerus and consequently the patient's stature, exhibit no significant variation. In situations where the greater tuberosity (GT) and the border of the acromion are inaccessible due to reasons such as trauma, the tip of the coracoid process can serve as a dependable bone landmark for establishing a secure surgical margin.

Transfer of Motor Fascicle From the Ulnar Nerve to the Axillary Nerve by Posterior Access. New Approach.

ABSTRACT: We describe a new technique of transferring the motor branch ulnar nerve (UN) to the axillary nerve (AN) by posterior approach. Three patients with C5, C6, and C7 brachial plexus injury were operated. By supraclavicular approach, the spinal accessory was transferred to the suprascapular nerve. By posterior approach in the arm, the AN was identified within the quadrilateral space, and the UN was identified medially with intrafascicular dissection of a motor fascicle, which is lifted to 4 cm in length and transferred to AN. By medial approach, a motor branch from the median nerve is transferred to the biceps nerve. At a follow-up minimum of 10 months, the maximum abduction was 160 and the minimum 90 degrees. This technique, neurotization of the AN with fascicles of the UN, spinal accessory to suprascapular nerve, and median nerve branch to biceps nerve are indicated in C5-C7 avulsion when there is no radial nerve available. LEVEL OF EVIDENCE: Level IV.

Optimizing donor fascicle selection in Oberlin's procedure: A retrospective review of anatomical variability using intraoperative neuromonitoring.

BACKGROUND: Transfer of the fascicle carrying the flexor carpi ulnaris (FCU) branch of the ulnar nerve (UN) to the biceps/brachialis muscle branch of the musculocutaneous nerve (Oberlin's procedure), is a mainstay technique for elbow flexion restoration in patients with upper brachial plexus injury. Despite its widespread use, there are few studies regarding the anatomic location of the donor fascicle for Oberlin's procedure. Our report aims to analyze the anatomical variability of this fascicle within the UN, while obtaining quantifiable, objective data with intraoperative neuromonitoring (IONM) for donor fascicle selection. METHODS: We performed a retrospective review of patients at our institution who underwent an Oberlin's procedure from September 2019 to July 2023. We used IONM for donor fascicle selection (greatest FCU muscle and least intrinsic hand muscle activation). We prospectively obtained demographic and electrophysiological data, as well as anatomical location of donor fascicles and post-surgical morbidities. Surgeon's perception of FCU/intrinsic muscle contraction was compared to objective muscle amplitude during IONM. RESULTS: Eight patients were included, with a mean age of 30.5 years and an injury-to-surgery interval of 4 months. Donor fascicle was located anterior in two cases, posterior in two, radial in two and ulnar in two patients. Correlation between surgeon's perception and IONM findings were consistent in six (75%) cases. No long term motor or sensory deficits were registered. CONCLUSIONS: Fascicle anatomy within the UN at the proximal arm is highly variable. The use of IONM can aid in optimizing donor fascicle selection for Oberlin's procedure.

The 2-by-2 Inch "Key Window" in the Upper Extremity: An Anatomical Appraisal of the Accessibility and Proximity of the Major Nerves and Vessels.

BACKGROUND: The brachial plexus is a network of nerves located between the neck and axilla, which receives input from C5-T1. Distally, the nerves and blood vessels that supply the arm and forearm form a medial neurovascular bundle. The purpose of this study was to illustrate that a peripheral nerve dissection via a 2 × 2 inch window would allow for identification and isolation of the major nerves and blood vessels that supply the arm and forearm. METHODS: A right side formalin-fixed latex-injected cadaveric arm was transected at the proximal part of the axillary fold and included the scapular attachments. Step-by-step anatomical dissection was carried out and documented with three-dimensional digital imaging. RESULTS: A 2 × 2 inch window centered 2 inches distal to the axillary fold on the medial surface of the arm enabled access to the major neurovascular structures of the arm and forearm: the median nerve, ulnar nerve, medial antebrachial cutaneous nerve, radial nerve and triceps motor branches, musculocutaneous nerve and its biceps and brachialis branches and lateral antebrachial cutaneous nerve, basilic vein and brachial artery and vein, and profunda brachii artery. CONCLUSIONS: Our study demonstrates that the majority of the neurovascular supply in the arm and forearm can be accessed through a 2 × 2 inch area in the medial arm. Although this "key window" may not be entirely utilized in the operative setting, our comprehensive didactic description of peripheral nerve dissection in the cadaver laboratory can help in safer identification of complex anatomy encountered during surgical procedures.

Image analysis comparison of nerve staining with food dye, methylene blue or tissue marker.

OBJECTIVE: Novel locoregional techniques use dye studies to confirm successful nerve targeting. The goal was to objectively quantify and compare nerve staining characteristics of dye mixtures commonly reported in the literature using image analysis software. STUDY DESIGN: Prospective, randomized cadaveric study. METHODS: Thirty-six brachial plexus nerves from unpreserved pig cadavers were randomized into three groups of 12: FD (1:10 mixture of blue food dye and bupivacaine 0.5%), MB (methylene blue 1%) and TM (0.1:10 mixture of blue tissue marker and lidocaine 2%). Nerves were immersed in dye for 1, 15, 30 or 60 minutes (n = 3 each). Images of nerves before immersion (baseline) and at each time point with epineurium intact (superficial staining) and after longitudinal bisection (deep staining) were processed using image analysis software. Color saturation values were divided into quartiles (dark, medium-dark, medium-light or light). Percentage of stained nerve area in each quartile was calculated and compared using two-way anova. RESULTS: Superficially, at minute 1, dark saturation covered 40% of nerve area in FD versus 19% in MB (p = 0.04) and 0% in TM (p < 0.0001). In bisected nerves, dark and medium-dark saturations occurred only in FD; medium-light saturation comprised anywhere from 4% to 22.5% over time in FD versus <1% at any time in MB (p = 1.000; p = 0.343; p = 0.383; p = 0.262). Deep staining was not found in TM at any point. CONCLUSION AND CLINICAL RELEVANCE: Food dye rapidly stains superficial and deep nerve layers. Based on these characteristics, investigators can choose the appropriate dye for their study.

Infraspinatus-teres minor (ITM) interfascial block: a novel approach for combined suprascapular and axillary nerve block.

BACKGROUND: Combined suprascapular and axillary nerve block could be an analgesic option for shoulder pain control. The current description of this technique requires performing the block procedures at two different sites without consideration for catheter placement. We hypothesized that a single site injection to the interfascial plane between the infraspinatus and teres minor would result in an injectate spread to the suprascapular and axillary nerves. METHODS: We performed 10 injections with this approach using 25 mL dye solution in 10 shoulders of five unembalmed cadavers. Also, we described three case reports, two single-injection cases and one catheter-placement case, using this approach in patients with acute postsurgical pain and chronic pain in their shoulder region. RESULTS: In cadaveric evaluations, dye spreading to the suprascapular nerves on the infraspinatus fossa and the spinoglenoid notch cephalad and axillary nerves in the quadrilateral space caudally were observed in all injections. In addition, the most posterolateral part of the joint capsule was stained in 8 out of 10 injections. There was no dye spreading on the nerves to the subscapularis or lateral pectoral nerves. Clinically successful analgesia with no adverse events was achieved in all three cases. CONCLUSION: Our anatomical and clinical observations demonstrated that an injection to the interfascial plane between the infraspinatus and teres minor consistently achieved injectate spreading to both suprascapular and axillary nerves, which innervate the glenohumeral joint.

Optimized 3D brachial plexus MR neurography using deep learning reconstruction.

OBJECTIVE: To evaluate whether 'fast,' unilateral, brachial plexus, 3D magnetic resonance neurography (MRN) acquisitions with deep learning reconstruction (DLR) provide similar image quality to longer, 'standard' scans without DLR. MATERIALS AND METHODS: An IRB-approved prospective cohort of 30 subjects (13F; mean age = 50.3 ± 17.8y) underwent clinical brachial plexus 3.0 T MRN with 3D oblique-coronal STIR-T2-weighted-FSE. 'Standard' and 'fast' scans (time reduction = 23-48%, mean = 33%) were reconstructed without and with DLR. Evaluation of signal-to-noise ratio (SNR) and edge sharpness was performed for 4 image stacks: 'standard non-DLR,' 'standard DLR,' 'fast non-DLR,' and 'fast DLR.' Three raters qualitatively evaluated 'standard non-DLR' and 'fast DLR' for i) bulk motion (4-point scale), ii) nerve conspicuity of proximal and distal suprascapular and axillary nerves (5-point scale), and iii) nerve signal intensity, size, architecture, and presence of a mass (binary). ANOVA or Wilcoxon signed rank test compared differences. Gwet's agreement coefficient (AC2) assessed inter-rater agreement. RESULTS: Quantitative SNR and edge sharpness were superior for DLR versus non-DLR (SNR by + 4.57 to + 6.56 [p < 0.001] for 'standard' and + 4.26 to + 4.37 [p < 0.001] for 'fast;' sharpness by + 0.23 to + 0.52/pixel for 'standard' [p < 0.018] and + 0.21 to + 0.25/pixel for 'fast' [p < 0.003]) and similar between 'standard non-DLR' and 'fast DLR' (SNR: p = 0.436-1, sharpness: p = 0.067-1). Qualitatively, 'standard non-DLR' and 'fast DLR' had similar motion artifact, as well as nerve conspicuity, signal intensity, size and morphology, with high inter-rater agreement (AC2: 'standard' = 0.70-0.98, 'fast DLR' = 0.69-0.97). CONCLUSION: DLR applied to faster, 3D MRN acquisitions provides similar image quality to standard scans. A faster, DL-enabled protocol may replace currently optimized non-DL protocols.

Typical brachial plexus: the legacy of a forgotten anatomist, Abram T. Kerr (1873-1938).

The brachial plexus, a complex network of nerves responsible for innervating the upper limb, exhibits remarkable anatomical variations. This editorial explores the composite drawing of a "typical" brachial plexus portrayed by Abram T. Kerr in 1918. This composite drawing of the typical brachial plexus stands as a critical contribution to the field of anatomy and surgery, and encapsulates the most prevalent patterns of formation, branching, and origins within the brachial plexus, offering a statistical map of its common variants. Kerr portrays the typical brachial plexus as a foundational resource for anatomists and medical professionals seeking to navigate the intricate landscape of this neural structure. It serves as a hypothetical model, reflecting the common arrangement of trunks, cords, and branches, shedding light on the typical composition of the plexus observed in most individuals. Beyond being a visual representation, the 'typical' brachial plexus provides a bridge between theoretical knowledge and practical applications, aiding in the identification of variations and deviations in surgical contexts. This composite drawing enhances our comprehension of the intricate and ever-evolving anatomy of the brachial plexus, reinforcing its role as a fundamental reference point for anatomical studies and clinical practice.

A new classification of the shoulder girdle muscles in domestic fowl based on their innervation from the brachial plexus.

Many studies have described the muscle anatomy of the domestic fowl (Gallus gallus domesticus), a commonly used animal in developmental experiments. However, some major differences in terminology existed among studies, making it difficult to precisely discuss the muscle homologies between domestic fowl and other animals. In this study, the innervations of shoulder girdle muscles in five sides of the domestic fowl were elucidated and the homology of the shoulder girdle muscles between domestic fowl and other tetrapods was discussed using terminology that conforms to Nomina Anatomica Avium (1993). Unlike previous descriptions, the supracoracoideus, being developed in domestic fowl, is thought to have a different muscular origin from the deltoid muscle. The coracobrachialis cranialis, coracobrachialis caudalis and coracobrachialis muscles, previously described as the coracobrachialis muscle group, had different innervations; the coracobrachialis cranialis should be grouped with the deltoid muscles, and the coracobrachialis caudalis appears to belong to the pectoral muscle group. I propose that the subcoracoscapularis in domestic fowl, keeping the reptilian form, is divided into the subcoracoideus and subscapularis muscles. Based on the innervation, the subscapularis in domestic fowl is homologous with the subscapularis in reptiles and a major part of the subscapularis in mammals. Unlike the descriptions in previous studies, the scapulohumeralis cranialis and caudalis in the domestic fowl in this study, being innervated by the common branch, were found to have a close relationship with the subcoracoscapularis muscle. Based on the observations in this study, a new classification of the shoulder girdle muscles in domestic fowl is proposed.

High-resolution ultrasound of the supra- and infraclavicular levels of the brachial plexus including the axillary nerve: imaging anatomy based on multiplanar reconstructions and technical guide.

PURPOSE: The diagnosis of peripheral nerve injuries remains challenging. Electromyography and nerve conduction studies do not allow precise localization of the lesion and differentiation between lesions in continuity and non-continuity in cases with complete axonotmesis. Improved ultrasound technology allows the examination of almost the entire peripheral nervous system. The complex sono-anatomy of the brachial plexus outside of the standard scanning planes makes it difficult to access this region. METHODS: On the basis of the Visible Human Project of the National Institutes of Health (NIH), multiplanar reconstructions were created with the 3D Slicer open-source software in the various planes of the ultrasound cross-sections. The ultrasound examination itself and the guidance of the ultrasound probe in relation to the patient were recorded as video files and were synchronized through the audio channel. Subsequently, image matching was performed. RESULTS: Multiplanar reconstructions facilitate visualization of anatomical regions which are challenging to access thereby enabling physicians to evaluate the course of the peripheral nerve of interest in dynamic conditions. Sonographically visible structures could be reproducibly identified in single-frame analysis. CONCLUSION: With precise knowledge of the ultrasound anatomy, the nerve structures of the brachial plexus can also be dynamically assessed almost in their entire course. An instructional video on ultrasound of the brachial plexus supplements this manuscript and has been published on Vimeo.com.

Anatomical Variations of the Musculocutaneous Nerve in the Human Fetus.

OBJECTIVES: Knowing the motor branches and variations of the musculocutaneous nerve to the muscles along its course will facilitate the treatment of flexor spasticity and supracondylar fractures of the humerus in order to minimize nerve lesion. In fetal cadavers, the purpose of our study was to determine the number and course of the formation variations and motor branches of the musculocutaneous nerve. The significance of studying fetal nerve variations is due to injury to the brachial plexus roots during birth. METHODS: Our study was conducted using the anatomical dissection technique on 102 upper limbs from 51 fetuses ages ranged from 17 to 40 weeks. Throughout its course, the variations and motor branches of the musculocutaneous nerve were analyzed. RESULTS: In 13.7% of cases, the musculocutaneous nerve did not pierce the coracobrachialis. The musculocutaneous nerve gave the muscles 1-3 motor branches. Additionally, motor branches terminated with 1-7 fringes. The biceps brachii motor branches of the musculocutaneous nerve were typed. Accordingly, 15.6% were type 1A, 3.9% were type 1B, 35.4% were type 1C, and 19.6% were type 1D. It was determined that 23.5% of the extremities were type 2 and that 1.9% were type 3. The distance between the musculocutaneous nerve's motor branches and the acromion was proportional to the arm's length. There were no statistically significant differences between the sides and genders for any measurement. CONCLUSIONS: Our study's findings will aid in the diagnosis and treatment of pediatrics, orthopedics, surgical sciences, and radiology conditions. It reduces the risk of iatrogenic injury and postoperative complications. We also believe that our research will serve as a resource for anatomists and other scientists.

Description of the neuroanatomy of the brachial plexus in South American lizards. Phylogenetic implications.

Few studies considered the anatomy of the nerve plexuses and musculature associated with them in ectothermic sauropsids. Based on differentiated Sudan Black B staining and conventional dissections, we describe the neuroanatomy of the brachial plexus, its main associated nerves, and muscles. For that, representatives of the genera Diplolaemus, Liolaemus, Phymaturus, and Tropidurus were selected. Based on this, potentially useful characters for phylogenetic analysis were described. Our results show that the brachial plexus can be formed by four, five, or six nerve branches. The brachial flexor trunk, circumflex, interosseous, median, radial, subscapulocoracoid, supracoracoid, and ulnar nerves were identified. Regarding the muscles innervated by the main nerves, the following muscles were identified: biceps brachii, deltoideus scapularis, latissimus dorsi, levator scapulae, pectoralis, serratus thoracis, trapezius, triceps longus caudalis, and triceps longus lateralis. Phylogenetic analyzes revealed 31 potential synapomorphies. There exists evidence that neuroanatomy studies in a phylogenetic context could provide useful information helping to elucidate the relationships between taxonomic groups.