Does the motor branch of the long head of the triceps brachii arise from the radial nerve?

Diagnostic ultrasonography of upper extremity dynamic compressive neuropathies in athletes: A narrative review

PURPOSE

This narrative review identifies and summarizes current evidence for diagnostic ultrasonographic evaluation of upper extremity dynamic compressive neuropathies affecting athletes.

METHODS

Relevant literature was identified using the PubMed database and then summarized.

RESULTS

The compressive neuropathies affecting athletes we identified included: neurogenic thoracic outlet syndrome, pectoralis minor syndrome, quadrilateral space syndrome, suprascapular nerve entrapment, proximal median nerve entrapment or bicipital aponeurosis/lacertus fibrosus (lacertus syndrome), radial tunnel syndrome, and cubital tunnel syndrome. Symptoms may develop only during specific sport activity, after specific sport-related trauma, or in setting of overuse during sport. Diagnostic ultrasound strategies assessing compressive neuropathies focus on static evaluation of nerves and surrounding structures, as well as dynamic evaluation of these structures in certain degrees of shoulder abduction, elbow flexion, or forearm pronation.

CONCLUSION

Ultrasonography can be used as a diagnostic tool in assessing upper extremity dynamic compressive neuropathies. Ultrasound allows for dynamic evaluation of these rare conditions, especially for athletes who primarily develop symptoms during movement or participation in sport.

A Comprehensive Review of Topography and Axon Counts in Upper-Extremity Peripheral Nerves: A Guide for Neurotization

Purpose

Currently, no comprehensive database detailing topography and axon counts exists. This study aims to review the axon counts and topography of the major peripheral motor nerves of the upper extremity to allow for optimal surgical planning for peripheral nerve reconstruction via neurotization.

Methods

Peer-reviewed journal articles were identified through PubMed, ScienceDirect, Google Scholar, and CENTRAL. Studies were included for review based upon the identification of the described topography or axon count of any upper-extremity peripheral motor nerve. Animal research, laboratory studies, and unpublished studies were excluded from our review. A total of 43 studies were identified, and 38 of these met the inclusion criteria. Statistical analysis was performed to determine axon count averages for all upper extremity motor nerves identified in the included studies.

Results

Thirty-eight studies were reviewed, giving insights into the topography and axon counts of the major peripheral nerves of the upper extremity, including the brachial plexus and its terminal branches as well as common donor nerves such as the spinal accessory nerve and intercostal nerves. Studies showed considerable variability in reported axon counts.

Conclusions

Existing data were relatively weak and included several case reports and series. Taking this into consideration, we posit that there is a need for further studies of upper-extremity nerve axon counts that include large study populations and more consistent methods of nerve specimen analysis.

Clinical relevance

Understanding the topographical anatomy of donor and recipient nerves, as well as appropriately matching the motor axon counts for each donor and recipient, is helpful in upper-extremity nerve reconstruction.

Triceps and cutaneous radial nerve branches investigated via an axillary anterior arm approach: new findings in a fresh-cadaver anatomical study

OBJECTIVE

The authors sought to describe the anatomy of the radial nerve and its branches when exposed through an axillary anterior arm approach.

METHODS

Bilateral upper limbs of 10 fresh cadavers were dissected after dyed latex was injected into the axillary artery.

RESULTS

Via the anterior arm approach, all triceps muscle heads could be dissected and individualized. The radial nerve overlaid the latissimus dorsi tendon, bounded by the axillar artery on its superior surface, then passed around the humerus, together with the lower lateral arm and posterior antebrachial cutaneous nerve, between the lateral and medial heads of the triceps. No triceps motor branch accompanied the radial nerve's trajectory. Over the latissimus dorsi tendon, an antero-inferior bundle, containing all radial nerve branches to the triceps, was consistently observed. In the majority of the dissections, a single branch to the long head and dual innervations for the lateral and medial heads were observed. The triceps long and proximal lateral head branches entered the triceps muscle close to the latissimus dorsi tendon. The second branch to the lateral head stemmed from the triceps lower head motor branch. The triceps medial head was innervated by the upper medial head motor branch, which followed the ulnar nerve to enter the medial head on its anterior surface. The distal branch to the triceps medial head also originated near the distal border of the latissimus dorsi tendon. After a short trajectory, a branch went out that penetrated the medial head on its posterior surface. The triceps lower medial head motor branch ended in the anconeus muscle, after traveling inside the triceps medial head. The lower lateral arm and posterior antebrachial cutaneous nerve followed the radial nerve within the torsion canal. The lower lateral brachial cutaneous nerve innervated the skin over the biceps, while the posterior antebrachial cutaneous nerve innervated the skin over the lateral epicondyle and posterior surface of the forearm. The average numbers of myelinated fibers were 926 in the long and 439 in the upper lateral head and 658 in the upper and 1137 in the lower medial head motor branches.

CONCLUSIONS

The new understanding of radial nerve anatomy delineated in this study should aid surgeons during reconstructive surgery to treat upper-limb paralysis.

Brachial Plexus Injuries - Review of the Anatomy and the Treatment Options

Brachial plexus injuries are still challenging for every surgeon taking part in treating patients with BPI. Injuries of the brachial plexus can be divided into injuries of the upper trunk, extended upper trunk, injuries of the lower trunk and swinging hand where all of the roots are involved in this type of the injury. Brachial plexus can be divided in five anatomical sections from its roots to its terminal branches: roots, trunks, division, cords and terminal branches. Brachial plexus ends up as five terminal branches, responsible for upper limb innervation, musculocutaneous, median nerve, axillary nerve, radial and ulnar nerve. According to the findings from the preoperative investigation combined with clinically found functional deficit, the type of BPI will be confirmed and that is going to determine which surgical procedure, from variety of them (neurolysis, nerve graft, neurotization, arthrodesis, tendon transfer, free muscle transfer, bionic reconstruction) is appropriate for treating the patient.

Comparison between long and lower medial head triceps branches in dual neurotization for shoulder function restoration in upper brachial plexus palsy

PURPOSE

In upper brachial plexus injury (UBPI), restoring shoulder function is crucial. This study compares the transfer of long and lower medial heads of triceps branches to the axillary nerve to achieve proper restoration of function.

PATIENTS AND METHODS

A retrospective comparative study was conducted between two groups of patients with (UBPI). Group I patients (10) [mean age: 19 ± 10.6 years] were managed by transferring triceps long head branch to axillary nerve while group II patients (8) [mean age: 26 ± 9.6 years] were managed by triceps lower medial head branch transfer. The mean time from injury to surgery was 6 ± 1.3 and 5 ± 1.7 months respectively. All patients were followed up for a minimum of 12 months with the assessment of VAS, DASH score, active range of motion (AROM) and strength of shoulder abduction and external rotation; in addition to shoulder endurance and strengths of donors. Postoperative, three-monthly, electrodiagnostic assessments were performed.

RESULTS

Postoperatively, the mean VAS and DASH scores; in addition to endurance time, showed significant enhancement in both groups. Patients in both groups have accomplished a mean abduction (AROM) of 98° ± 27.9 and 97° ± 11.9 respectively. The mean external rotation (AROM) was 48° ± 18.4 and 47° ± 9.2 respectively. Furthermore, group II patients had less triceps morbidity in addition to earlier and enhanced electrophysiological recovery.

CONCLUSIONS

Dual neurotization for shoulder function restoration in (UBPI) is capable of providing proper functional results with minimal donor morbidity. The triceps lower medial branch provides an excelling donor due to less triceps morbidity, extra length; yet, earlier and enhanced electrophysiological recovery.

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.

Use of the Humeral Head as a Reference Point to Prevent Axillary Nerve Damage during Proximal Fixation of Humeral Fractures: An Anatomical and Radiographic Study

Introduction

Treatment of proximal humeral fractures with plate osteosynthesis or intramedullary nail fixation in humeral shaft fractures with a proximal locking bolt carries the risk of iatrogenic injury of the axillary nerve. The purpose of this anatomical study is to define a more reliable safe zone to prevent iatrogenic axillary nerve injury using the humeral head instead of the acromion as a (radiographic) reference point during operative treatment.

Materials and methods

Anatomical dissection and labeling of the axillary nerve and branches was performed on 10 specially embalmed human specimens. Standard AP and straight lateral radiographs were made. The distances were measured indirectly from the cranial tip of the humerus to the axillary nerve on radiographs.

Results

The median distance from the cranial tip of the humerus to the axillary nerve was 52 mm. The mean number of axillary nerve branches was 3. The distances from the cranial tip of the humerus to the nerve (branch) varied from 23 to 78 mm. The median distance from the proximal (anterior) branch was 36 mm, to the second branch 47 mm, 54 mm to the third branch and 73 mm to the fourth branch. The axillary nerve moves along with the humerus in cranial and caudal direction when the subacromial space varies.

Conclusion

This study shows that the position of the axillary nerve can be better determent using the cranial tip of the humerus as a reference point instead of the acromion. Furthermore, it is unsafe to place the proximal locking bolts in the zone between 24 mm and 78 mm from the cranial tip of the humerus. The greatest chance to cause a lesion of the main branch of the axillary nerve is in the zone between 48 mm and 58 mm caudal from the tip of the humeral head.

How to cite this article

Theeuwes HP, Potters JW, Bessems JHJM, et al. Use of the Humeral Head as a Reference Point to Prevent Axillary Nerve Damage during Proximal Fixation of Humeral Fractures: An Anatomical and Radiographic Study. Strategies Trauma Limb Reconstr 2020;15(2):63–68.

Ultrasonographic measurement of the cross-sectional area of the axillary nerve

INTRODUCTION

The objectives of this study were to determine normal reference values for ultrasonographic measurement of the cross-sectional area (CSA) of the axillary nerve and to standardize the measurement methods.

METHODS

Sixty healthy volunteers were evaluated. Ultrasonography was performed with the shoulder positioned in 100°-120° abduction and 90° external rotation. The CSA of the axillary nerve was measured bilaterally.

RESULTS

The normal CSA of the right axillary nerve was 2.9 ± 1.1 mm² . The side-to-side discrepancy was 22.8% ± 17.8%.

DISCUSSION

These reference values may be helpful for investigating pathologies involving the axillary nerve.

Surgical Implications of Innervation Pattern of the Triceps Muscle: A Cadaveric Study

The innervation pattern of triceps is complex and not fully comprehended. Anomalous innervations of triceps have been described by various authors. We have attempted to delineate the nerve supply of the triceps and documented the anomalous innervations of its different heads. The brachial plexus and its major branches (in the region of the axilla and arm) and triceps were dissected in 36 embalmed cadaver upper limbs. Long head received one branch from radial nerve in 31 (86%) specimens. Four (11%) specimens received two branches including one that had dual innervation from the radial and axillary nerves, and one (3%) specimen had exclusive innervation from a branch of the axillary nerve. Medial head received two branches arising from the radial nerve in 34 (94%) specimens. One (3%) specimen received three branches from the radial nerve whereas one (3%) had dual supply from the radial and ulnar nerves. Lateral head received multiple branches exclusively from the radial nerve, ranging from 2 to 5, in all (100%) specimens. Knowledge of the variations in innervation of the triceps would not only help the surgeon to avoid inadvertent injury to any of the nerve branches but also offers new options for nerve and free functional muscle transfers.

Innervation of the Long Head of the Triceps Brachii in Humans-A Fresh Look

The triceps brachii muscle occupies the posterior compartment of the arm in humans and has three heads. The lateral and medial heads originate from the humerus and the long head arises from the infraglenoid tubercle of the scapula. All heads form a common tendon that inserts onto the olecranon and the deep antebrachial fascia on each side of it. Each head receives its own motor branch, which all are thought to originate from the radial nerve. However, several studies reported that the motor branch of the long head of the triceps (LHT) arises from the axillary nerve or the posterior cord. Here, we dissected 27 triceps in 15 cadavers to analyze the innervation of the LHT and found only radial innervation, which contradicts those studies. We examined studies reporting that the motor branch to the LHT in humans does not arise from the radial nerve as well as studies of the triceps in primates. Occasional variations of the innervation of skeletal muscles are normal, but a change of principal motor innervation from radial to axillary nerve has important implications. This is because the axillary nerve is often involved during shoulder injuries. The precise identification of the prevalence of axillary versus radial innervation is therefore clinically relevant for surgery, nerve drafting, and occupational and physical therapy. We conclude that the primary motor branch to the LHT arises from the radial nerve but axillary/posterior cord innervations occur occasionally. We suggest the development of a standard methodology for further studies. Anat Rec, 301:473-483, 2018. © 2018 Wiley Periodicals, Inc.

Functional Morphology and Behavioral Correlates to Postcranial Musculature

In this the second issue of a two-volume set of the Anatomical Record on the relationship between muscle functional morphology and behavior, the focus is on the postcranial musculature. Traditionally, when talking of the postcranium we think of the skeletal parts that primarily provide the lever system necessary for body movements. However, without the force produced by muscle, the postcranial skeleton could not perform these or most other tasks. In this special issue, our colleagues present ten papers that focus on postcranial muscle morphology and function from different perspectives. They include papers on forelimb and hindlimb muscle functional morphology of vertebrates, including lizards, bats, primates, a carnivoran and a rodent, and involved in different substrate use (arboreal, terrestrial, and flying) and locomotion behavior (quadrupedal, leaper, and suspensory) along with a historical overview to help bookend the contextualization of the issues. The picture that these papers provide is one of great liveliness in the field of muscle functional morphology where both young students and affirmed professors continue to contribute with both traditional approaches and new techniques to further our knowledge of muscle morphology and its relationship with animal behavior. Anat Rec, 301:419-423, 2018. © 2018 Wiley Periodicals, Inc.

Accessory subscapularis muscle - A forgotten variation?

The quadrangular space is a space in the axilla bounded by the inferior margin of the teres minor muscle, the superior margin of the teres major muscle, the lateral margin of the long head of the triceps brachii muscle and the surgical neck of the humerus, medially. The axillary nerve (C5-C6) and the posterior circumflex humeral artery and veins pass through this space in order to supply their territories. The subscapularis muscle is situated into the scapular fossa and inserts itself into the lesser tubercle of the humerus, thus helping stabilize the shoulder joint. A supernumerary muscle known as accessory subscapularis muscle originates from the anterior surface of the muscle and usually inserts itself into the shoulder joint. It is a rare variation with few reports of its existence and incidence. We present a case of the accessory subscapularis muscle in a male cadaver fixated with a 10% formalin solution. The muscle passed anteriorly to the axillary nerve, thus, predisposing an individual to quadrangular space compression syndrome. We perform a review of the literature and address its clinical, anthropological and anatomical significance.

A systematic review of surface electromyography analyses of the bench press movement task

BACKGROUND

The bench press exercise (BP) plays an important role in recreational and professional training, in which muscle activity is an important multifactorial phenomenon. The objective of this paper is to systematically review electromyography (EMG) studies performed on the barbell BP exercise to answer the following research questions: Which muscles show the greatest activity during the flat BP? Which changes in muscle activity are related to specific conditions under which the BP movement is performed?

STRATEGY

PubMed, Scopus, Web of Science and Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library were searched through June 10, 2016. A combination of the following search terms was used: bench press, chest press, board press, test, measure, assessment, dynamometer, kinematics and biomechanics. Only original, full-text articles were considered.

RESULTS

The search process resulted in 14 relevant studies that were included in the discussion. The triceps brachii (TB) and pectoralis major (PM) muscles were found to have similar activity during the BP, which was significantly higher than the activity of the anterior deltoid. During the BP movement, muscle activity changes with exercise intensity, velocity of movement, fatigue, mental focus, movement phase and stability conditions, such as bar vibration or unstable surfaces. Under these circumstances, TB is the most common object of activity change.

CONCLUSIONS

PM and TB EMG activity is more dominant and shows greater EMG amplitude than anterior deltoid during the BP. There are six factors that can influence muscle activity during the BP; however, the most important factor is exercise intensity, which interacts with all other factors. The research on muscle activity in the BP has several unresolved areas, such as clearly and strongly defined guidelines to perform EMG measurements (e.g., how to elaborate with surface EMG limits) or guidelines for the use of exact muscle models.

Variations in the Innervation of the Long Head of the Triceps Brachii: A Cadaveric Investigation

BACKGROUND

Some leading anatomy texts state that all three heads of the triceps brachii are innervated by the radial nerve. The posterior cord of the brachial plexus bifurcates to terminate as the radial and axillary nerves. Studies have noted the presence of axillary innervation to the long head of the triceps brachii muscle, patterns different from the classic exclusive radial nerve supply. An understanding of these variations may assist the clinician in the assessment of shoulder weakness and in preoperative and operative planning of radial and axillary neuropathies.

QUESTIONS/PURPOSE

We aimed to further investigate, in cadaver dissections, the prevalence of axillary nerve contribution to the innervation of the long head of the triceps brachii.

METHODS

We performed bilateral brachial plexus dissections on 10 embalmed cadavers combining anterior axillary and posterior subscapular approaches. Two additional unilateral cadaveric brachial plexuses were dissected. The posterior cords were fully dissected from the roots distally. The radial and axillary nerves were followed to their muscle insertion points, the dissections were photographed, and the length of branching segments were measured.

RESULTS

Of the 10 paired cadavers dissected (20 specimens), in only one of the 10 cadavers was the classic innervation pattern of radial nerve observed. The other nine cadavers had varying patterns of radial and axillary nerve innervation, The observed patterns were radial and axillary (dual) on one side with radial alone on the other, dual innervation bilaterally, or axillary with contralateral radial innervation. The two additional unilateral dissected specimens were innervated exclusively by the axillary nerve.

CONCLUSIONS

Gross and surgical anatomy sources state that the radial nerve is the sole nerve supply to the long head of the triceps. In our study sample, pure radial innervation of the long head of the triceps brachii was not the predominant nerve pattern. We found four other studies that looked at axillary innervation of the long head of the triceps; of the 62 total cadaver shoulders examined in those studies, 71% were found to have nonclassic innervation patterns. Nonclassic patterns may include purely axillary, dual, or posterior cord innervation to the long head of the triceps, and may account for the majority of innervation to the long head of the triceps. These are similar to our findings.

CLINICAL RELEVANCE

Understanding the innervation of the long head of the triceps and variations in axillary nerve course is critical to the clinical diagnosis of injury, surgical treatment options, and rehabilitation of axillary nerve injuries. With this information, the practitioner may have additional surgical options, clearer rationales for clinical situations, and explanations for patient outcomes.

Motor Nerve Transfers

Brachial plexus and peripheral nerve injuries are exceedingly common. Traditional nerve grafting reconstruction strategies and techniques have not changed significantly over the last 3 decades. Increased experience and wider adoption of nerve transfers as part of the reconstructive strategy have resulted in a marked improvement in clinical outcomes. We review the options, outcomes, and indications for nerve transfers to treat brachial plexus and upper- and lower-extremity peripheral nerve injuries, and we explore the increasing use of nerve transfers for facial nerve and spinal cord injuries. Each section provides an overview of donor and recipient options for nerve transfer and of the relevant anatomy specific to the desired function.

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.

Nerve transfer from triceps medial head and anconeus to deltoid for axillary nerve palsy

PURPOSE

To report our results with reconstruction of the axillary nerve by transferring the branch to the triceps lower medial head and anconeus to the anterior division of the axillary nerve.

METHODS

This study included 9 patients with isolated injury of the axillary nerve. Their average age ± SD was 35 ± 9 years, and the mean interval ± SD between injury and surgery was 6.6 ± 2.6 months. Through a posterior arm approach, the radial nerve branch to the lower triceps medial head and anconeus was transferred to the anterior division of the axillary nerve. We observed patients for a mean of 34 ± 7 months. At final evaluation, we measured range of shoulder motion, shoulder abduction and elbow extension strength, and abduction endurance. Patients were assessed via the deltoid extension lag test and abduction-in-internal-rotation test.

RESULTS

All patients recovered deltoid function and maintained full active elbow extension. Seven of 9 patients recovered from lagging abduction in internal rotation. Abduction strength improved from approximately 40% that of the normal side at 90° of abduction preoperatively to 60% of normal strength postoperatively. There was improved endurance in abduction from approximately 25% to 65% that of the normal side, which was sufficient to eliminate all reports of shoulder pain or fatigability.

CONCLUSIONS

Transfer of the radial nerve branch for the lower triceps medial head and anconeus to the anterior division of the axillary nerve proved to be an effective method of deltoid reinnervation.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Physical examination of upper extremity compressive neuropathies

A thorough history and physical examination are vital to the assessment of upper extremity compressive neuropathies. This article summarizes relevant anatomy and physical examination findings associated with upper extremity compressive neuropathies.

Pulsed radiofrequency lesioning of the axillary and suprascapular nerve in calcific tendinitis

The patient was a 45-year-female who presented with pain at right shoulder and right upper arm. The patient suffered from right shoulder and arm pain for 3 years and had pain management which was performed using medication and conservative management after she had been diagnosed with calcific tendinitis. However, substantial pain relief was not consistently achieved, and recurrence of pain was reported. Therefore, we performed right axillary nerve and suprascapular nerve block through pulsed radiofrequency. Two months after the procedure, the shoulder pain gradually subsided with the size reduction of the calcified nodule and she needed no more pain management.

Management of the flail elbow

Flail elbow is a relatively uncommon cause of elbow dysfunction. It is defined as the inability to position the arm in space for useful elbow function because of structural or neurologic inadequacies. Patient function is often severely compromised and treatment options are limited with moderate levels of success depending on etiology. This article reviews the various etiologies of dysfunctional elbow instability, their treatment options, and their expected outcomes.