Topographical anatomy of the radial nerve and its muscular branches related to surface landmarks

Vascular supply of the radial nerve and its terminal branches: an anatomical study

PURPOSE

The aim of this cadaveric study was to further describe the vascular supply of the radial, posterior interosseous and superficial radial nerves.

METHODS

11 cadaveric upper limbs, injected with colored latex, were dissected. Vascular afferents to the radial nerve, superficial radial nerve (SRN) and posterior interosseous nerve (PIN) were described and located. Their origin was identified and its distance to interepicondylar line was measured.

RESULTS

The radial nerve had an average of 3 vascular afferents (1-5), of septomuscular origin in 54% of cases. 46% came from adjacent arteries. The PIN had an average of 8 vascular afferents (6-14), arising from septomuscular branches in 82% of cases. The PIN was vascularized in 100% of cases by a large arterial plexus originating from the supinator muscle between its two heads. The SRN had an average of 4 vascular afferents (3-7). Before crossing the septum of the brachioradialis, vascularization was predominantly septomuscular; after crossing the septum, the nerve was exclusively vascularized by septocutaneous arteries.

CONCLUSION

This is the first study to describe the vascularization of the radial nerve and its terminal branches along their entire length. Our results are in line with the data available in the literature. An arterial plexus between the two heads of the supinator was surrounding the PIN in all cases. This vascular plexus might be involved in dynamic compression of the posterior interosseous nerve.

[Anatomical cartography of the radial nerve at the elbow level for intraradial nerve transfers for finger extension reconstruction in spastic upper limb - A cadaveric study]

INTRODUCTION

Upper limb spasticity is a surgical challenge, both in diminishing agonists spasticity and reconstructing antagonist function. Brachioradialis (BR) is often involved in elbow flexors spasticity. Finger extension is often impaired in spastic patients. This study aims to demonstrate the feasibility of BR motor branch to posterior interosseous nerve (PIN) during BR selective neurectomies, and to describe fascicles topography inside the radial nerve to facilitate PIN dissection.

MATERIAL AND METHOD

Ten upper limbs from 10 fresh frozen anatomical specimens were dissected. Motor branches to the BR, wrist extensors, supinator, PIN and radial sensory branch were identified. BR to PIN transfer was realized and its feasibility was studies (donor length, tensionless suture).

RESULTS

BR to PIN transfer was achievable in 9 out of 10 cases. The position of the sensory branch of the radial nerve was inferior or medial in all cases. The position of the PIN was lateral in 90% of the cases.

CONCLUSION

BR to PIN nerve transfer is achievable in most cases (90%). The lateral topography of the PIN and the inferomedial topography of the sensory branch in most cases allows for an easier intraoperative finding of the PIN when stimulation is not possible.

LEVEL

IV, feasibility study.

An unreported innervation of the coracobrachialis longus by the radial nerve: a potential pitfall for clinicians

PURPOSE

The aim of the presented case is to describe an unprecedented innervation of the coracobrachialis longus muscle by the radial nerve.

METHODS

An 82-year-old body donor at death was subjected to a routine anatomical dissection for teaching and research purposes at the Department of Anatomical Dissection and Donation in Lodz, Poland.

RESULTS

We have found an additional branch of the radial nerve, which departed from it just below its beginning. Its initial section ran alongside the radial nerve in the axilla, then headed medially accompanying superior ulnar collateral artery. Then, it reaches the coracobrachialis longus muscle and is the only one to innervate it.

CONCLUSIONS

The brachial plexus (BP) is very variable and well understood. Nevertheless, we must remember that there may still be variations in its structure, which may involve problems at every stage of diagnosis and treatment of diseases associated with its structures. Their knowledge is extremely important.

Minimally Invasive Plate Osteosynthesis (MIPO) Through the Posterior Approach for the Humerus: A Cadaveric Study

Background Minimally invasive plate osteosynthesis (MIPO) has been effectively used in femur and tibia fractures. MIPO in the humerus is conducted by anterior (most commonly used), lateral, and posterior approaches. However, in the anterior approach, in distal humeral diaphyseal fractures, there is a lack of adequate room for screw placement in the distal fragment for good stability. In such cases, the posterior approach for MIPO may be a propitious treatment method. However, the literature on MIPO using the posterior approach for humeral diaphyseal fractures is limited. This study aimed to evaluate the feasibility of MIPO through the posterior approach and study the association of radial nerve injury with MIPO through the posterior approach for the humerus. Methodology This experimental study was conducted in the Department of Orthopedics, Himalayan Institute of Medical Sciences, Dehradun, Uttarakhand, India, and 20 cadaveric arms (10 right and 10 left) of 11 embalmed (formalin) cadavers were included (seven males and four females). Cadavers were placed prone on the dissection table. The posterolateral tip of the acromion and lateral epicondyle of the humerus were used as bony landmarks that were marked under C-Arm (Ziehm Imaging, Orlando, FL, USA) using K wires (Kirschner wires, Surgical Holdings, Essex, UK). Two incisions on the posterior part of the arm were made, and the radial nerve was identified at the proximal incision. After creating a submuscular tunnel, a 3.5 mm extraarticular distal humeral locking compression plate (LCP) was introduced over the posterior surface of the humerus and fixed to the humerus distally with one screw and then adjusted proximally and fixed to the humerus with another screw in the proximal window, followed by placement of couple more screws under C-Arm. After plate fixation, the dissection was completed to meticulously explore the radial nerve. The radial nerve was examined thoroughly for any injury sustained after completion of dissection, from the triangular interval to the lateral intermuscular septum where the nerve enters the anterior chamber. The position of the radial nerve with respect to plate holes was noted. The distance from the posterolateral tip of the acromion to the lateral epicondyle was measured as humeral length. The medial and lateral points where radial nerve passed over the posterior surface of the humerus were measured from the posterolateral tip of the acromion and compared with the humeral length. Results In this study, the radial nerve was lying over the posterior surface of the humerus for a mean distance of 52.161 ± 5.16 mm. The mean distance at which the radial nerve crossed the medial and lateral borders of the posterior surface of the humerus, measured from the posterolateral tip of the acromion, was 118.34 ± 10.86 mm (40.07% of humeral length) and 170 ± 12.30 mm (57.57% of humeral length), respectively, and the mean humeral length in this study was 295.27 ± 17.94 mm. The radial nerve and its branches were found to be intact in all cases. The radial nerve was related to the fifth, sixth, and seventh holes, with the nerve lying most commonly over the sixth hole (3.5 mm extraarticular distal humerus locking plate). Conclusions The posterior approach of MIPO in humeral fractures is a safe and reliable treatment modality with minimal risk of radial nerve injury. The radial nerve can be safely identified at the spiral groove using the bony landmarks described in our study.

Two fingerbreadths, one finger's width: on the proximity of the radial nerve to the deltoid tuberosity

INTRODUCTION

The aim of this study was to find a convenient technique to evaluate the location of the radial nerve (RN) with reference to the deltoid tuberosity (DT).

MATERIALS AND METHODS

Sixty-eight upper extremities, embalmed using a modified version of Thiel's method, were included in the study. The interval between the tip of the greater tubercle of the humerus and the distal tip of the lateral humeral epicondyle (LE) was defined as humeral length (HL). The most prominent point of the DT was used as the point of reference. Through this point, a horizontal reference line which met the humeral axis at the dorsal side of the humeral shaft was simulated. The longitudinal distance between the crossing point of the horizontal line and the humeral axis and the RN was measured (distance 1). The interval between the intersection point and the reference point at the DT was measured (distance 2). Data were evaluated in centimeters.

RESULTS

For the whole sample, the HL averaged 31.0 cm (SD: 2.3; range 26.2-36.9). Distance 1 averaged 2.2 cm (SD: 0.3; range 1.6-3.1), and distance 2 averaged 1.2 cm (SD: 1.0; range 0-2.8). The HL was larger in the male group when compared to females (p < 0.001; males mean: 32.2 cm; females mean 29.5 cm). There was no difference regarding distance 2 (p = 0.59; males mean: 1.2 cm; females mean: 1.3 cm) between the sexes. Distance 1 was significantly (p = 0.02) larger in the male group (mean: 2.3 cm) when compared to females (mean: 2.1 cm). Concerning sides, there were no differences regarding all evaluated parameters (HL: p = 0.6; Distance 1: p = 0.6; distance 2: p = 0.8).

CONCLUSIONS

This study provides an easily applicable technique to localize the RN with reference to the DT.

Radial nerve compression: anatomical perspective and clinical consequences

The radial nerve is the biggest branch of the posterior cord of the brachial plexus and one of its five terminal branches. Entrapment of the radial nerve at the elbow is the third most common compressive neuropathy of the upper limb after carpal tunnel and cubital tunnel syndromes. Because the incidence is relatively low and many agents can compress it along its whole course, entrapment of the radial nerve or its branches can pose a considerable clinical challenge. Several of these agents are related to normal or variant anatomy. The most common of the compressive neuropathies related to the radial nerve is the posterior interosseus nerve syndrome. Appropriate treatment requires familiarity with the anatomical traits influencing the presenting symptoms and the related prognoses. The aim of this study is to describe the compressive neuropathies of the radial nerve, emphasizing the anatomical perspective and highlighting the traps awaiting physicians evaluating these entrapments.

Ultrasound of the Radial Nerve: A Pictorial Review

This pictorial review focuses on the ultrasound (US) appearance of the normal and pathological radial nerve (RN) and its branches and provides tips with which to locate them and avoid misinterpretation of normal findings. A wide range of our pathological cases are reviewed and presented to help in familiarizing the reader with common and uncommon clinical scenarios that affect the RN and its main branches.

Translation step-cut osteotomy for posttraumatic Cubitus Varus in adults: a retrospective study

BACKGROUND

Cubitus varus is a complex three-dimensional deformity. Various osteotomies have been introduced to correct this complex deformity. The objective of the present study was to evaluate clinical and functional outcomes of adult cubitus varus deformity treated with translation step-cut osteotomy.

METHODS

Seventeen consecutive patients with a mean age of 25 years (range, 19-50 years) who underwent translation step-cut osteotomy were enrolled in this study. Their average follow-up period was 28.2 months. Radiographic measurements preoperatively, 3-month postoperatively, and at the last follow-up were compared. Functional outcomes were assessed using Disabilities of the Arm, Shoulder and Hand (DASH), Mayo Elbow Performance Score (MEPS), and Oppenheim criteria.

RESULTS

The mean humerus-elbow-wrist angle improved from 14.7° ± 6.4° (range, 6°-23°) varus preoperatively to 12.1° ± 6.6° (range, 5°-20°) valgus postoperatively (p <  0.001). The lateral prominence index improved 9.6% from its preoperative value, showing no significant difference from that of a normal elbow. Osseous union was radiographically demonstrated in 16 patients (except one out of 17 patients) within a mean of 12.7 weeks (range, 8-18 weeks). The motion arc of the elbow at the last follow-up was not significantly (p > 0.05) different from that at the initial presentation. Based on Oppenheim criteria, results were excellent for 7, good for 8, and poor for 2 patients. Mean final DASH value and MEPS were 2.5 ± 3.8 points (range, 0-15 points) and 97.0 ± 5.8 points (range, 85-100 points), respectively. With regard to complications, one case had delayed union and one case had transient radial nerve injury.

CONCLUSION

Translation step-cut osteotomy using Y plate is an efficient procedure to correct varus alignment and flexion-extension deformities so that they are within normal limits of adults with post-traumatic cubitus varus deformity.

TRIAL REGISTRATION

Institutional Review Board of Jeonbuk National University Hospital (IRB No. 2020-01-020 ).

The Branching and Innervation Pattern of the Radial Nerve in the Forearm: Clarifying the Literature and Understanding Variations and Their Clinical Implications

BACKGROUND

This study attempted to clarify the innervation pattern of the muscles of the distal arm and posterior forearm through cadaveric dissection.

METHODS

Thirty-five cadavers were dissected to expose the radial nerve in the forearm. Each muscular branch of the nerve was identified and their length and distance along the nerve were recorded. These values were used to determine the typical branching and motor entry orders.

RESULTS

The typical branching order was brachialis, brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, supinator, extensor digitorum, extensor carpi ulnaris, abductor pollicis longus, extensor digiti minimi, extensor pollicis brevis, extensor pollicis longus and extensor indicis. Notably, the radial nerve often innervated brachialis (60%), and its superficial branch often innervated extensor carpi radialis brevis (25.7%).

CONCLUSIONS

The radial nerve exhibits significant variability in the posterior forearm. However, there is enough consistency to identify an archetypal pattern and order of innervation. These findings may also need to be considered when planning surgical approaches to the distal arm, elbow and proximal forearm to prevent an undue loss of motor function. The review of the literature yielded multiple studies employing inconsistent metrics and terminology to define order or innervation.

Safe Needle Insertion Locations for Motor Point Injection of the Triceps Brachii Muscle: A Pilot Cadaveric and Ultrasonography Study

Objective

To determine the location of the motor endplate zones (MoEPs) for the three heads of the triceps brachii muscles during cadaveric dissection and estimate the safe injection zone using ultrasonography.

Methods

We studied 12 upper limbs of 6 fresh cadavers obtained from body donations to the medical school anatomy institution in Seoul, Korea. The locations of MoEPs were expressed as the percentage ratio of the vertical distance from the posterior acromion angle to the midpoint of the olecranon process. By using the same reference line as that used for cadaveric dissection, the safe injection zone away from the neurovascular bundle was identified in 6 healthy volunteers via ultrasonography. We identified the neurovascular bundle and its location with respect to the distal end of the humerus and measured its depth from the skin surface.

Results

The MoEPs for the long, lateral, and medial heads were located at a median of 43.8%, 54.8%, and 60.4% of the length of the reference line in cadaver dissection. The safe injection zone of the medial head MoEPs corresponded to a depth of approximately 3.5 cm from the skin surface and 1.4 cm away from the humerus, as determined by sonography.

Conclusion

Correct identification of the motor points for each head of the triceps brachii would increase the precision and efficacy of motor point injections to manage elbow extensor spasticity.

"Triceps Brachii Muscle Response to Neurostimulation of the Radial Nerve during Axillary Plexus Blockade: Clinical, Anatomical and Histological Correlation"

Axillary plexus blockade is a common technique in clinical practice with a well-known pattern of structures around the brachial artery. Historically, the only proper response to radial nerve stimulation was considered to be extension of the hand and wrist. Twenty-five axillary blockades were assessed by ultrasound and neurostimulation; the principal objective was to correlate the needle position over the radial nerve with the anatomical and histological structure of that nerve. During the procedure, the needle was directed in two ways to reach the medial or lateral margin of the nerve: above the brachial artery or beneath it. Once the needle reached the nerve, the current was augmented gradually until a response was elicited. For the cadaveric anatomical study, eight axillae were dissected and histological samples were examined. The response of the triceps brachii muscle differed significantly between the two approaches to the radial nerve (P < 0.001), and the mean intensity of stimulation was significantly lower when the nerve was accessed above the artery (0.44 ± 0.15 mA) than below it (0.57 ± 0.17 mA) (P = 0.015). A triceps brachii motor response occurs at lower current intensity and lower needle-nerve distance when the radial nerve is accessed above the artery and over the latissimus dorsi tendon. These findings were correlated with the topography of the radial nerve in the axillary fossa. Clin. Anat. 33:578-584, 2020. © 2019 Wiley Periodicals, Inc.

Injury of the Radial Nerve in the Arm: A Review

Compression of the radial nerve is most commonly described at the supinator muscle (i.e., arcade of Frohse). However, radial nerve compression can occur in the arm. Therefore, the purpose of this article is to review both etiologies of radial nerve entrapment and the sites at which this can occur in the arm. The clinical presentation of radial nerve entrapment in the arm and how it differs from that of entrapment at other sites is reviewed and the conditions potentially predisposing to nerve entrapment are described. Particular attention is paid to the nerve’s course and potential variants of the anatomical structures in the arm. In each case, the recommended course of management for the neuropathy is described. Injury of the radial nerve can arise from a varied set of pathologies including trauma, tumors, anomalous muscles, and intramuscular injections. Physicians should have a good working knowledge of the anatomy and potential mechanisms for radial nerve injury.

Anatomic variant of the inferior lateral cutaneous branch of the radial nerve during the posterior approach to the humerus: a case report

Iatrogenic injury during the posterior approach to the humerus during operative fixation is not an uncommon occurrence. A comprehensive understanding of the normal anatomy and its variants is of paramount importance in order to avoid such injury. Typically, the inferior lateral cutaneous branch of the radial nerve originates towards the distal end of the humerus at the inferior portion of the spiral groove. Here, we report an important variant of this nerve, which originated significantly more proximal than expected, further emphasizing the importance of identification, dissection and protection of the radial nerve and its major branches.

Cross-sectional sonographic assessment of the posterior interosseous nerve

PURPOSE

Cross-sectional sonographic measurements are considered first-line confirmatory tests in diagnosing peripheral nerve entrapment syndromes. Our aim is to establish normal values of cross-sectional area of the posterior interosseous nerve (PIN) at the arcade of Frohse, the most common site of compression of this nerve.

METHODS

The PIN was identified with ultrasound on 50 healthy adults and 30 cadavers. Measurements of the cross-sectional area (CSA), antero-posterior (AP) and lateral (L) distances were taken immediately proximal and distal to the arcade of Frohse.

RESULTS

The mean AP and L distances of the PIN proximal to the arcade of Frohse were 0.111 cm (0 ± 0.021) and 0.266 cm (±0.058), respectively, while the mean AP and L distances of the PIN distal to the arcade of Frohse were 0.085 cm (±0.019) and 0.343 cm (±0.057), respectively. P squared testing showed a statistically significant difference between the AP and lateral distances of the PIN when comparing proximal and distal to the arcade (p ≤ 0.001). However, the mean CSA of the PIN measured immediately proximal to the arcade of Frohse was 0.022 cm(2) (±0.005); immediately distal to the arcade of Frohse, it was 0.023 cm(2) (±0.004). t test showed no statistical difference between the two regions (p = 0.11).

CONCLUSIONS

Our study has provided reference values for the PIN in healthy individuals at the arcade of Frohse. Although, there is a flattening of the nerve as it enters the supinator muscle, this should not be mistaken for nerve entrapment as the size of the nerve remains consistent.

Nerve transfers from branches to the flexor carpi radialis and pronator teres to reconstruct the radial nerve

PURPOSE

To present our method and results for transferring branches of the median nerve for radial nerve palsy or posterior cord lesions.

METHODS

We transferred 1 branch to the pronator teres to the branch to the extensor carpi radialis longus muscle and transferred the branch to the flexor carpi radialis to the posterior interosseous nerve. We carried out these transfers in 6 patients with radial nerve palsy or posterior cord lesions. We reviewed functional outcomes, Disabilities of the Arm, Shoulder and Hand scores, and Patient Evaluation Measure scores.

RESULTS

After 20 months of follow-up evaluation, all patients had recovered extensor carpi radialis longus activity of M4. Activity of the extensor carpi ulnaris was M3 in 2 patients and M4 in 4 patients. Extensor pollicis longus activity was M4 in all 6 cases. Metacarpophalangeal extension was M4 in 4 cases and M3 in 2 cases. The mean Disabilities of the Arm, Shoulder, and Hand score was 26 (range, 7-43), and the mean Patient Evaluation Measure score was 34 (range, 24-53).

CONCLUSIONS

Selective independent synergistic transfer of median nerve fascicles to the radial nerve branches has shown excellent results in the treatment of severe lesions of the radial nerve.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.