Anatomy and internal topography of the musculocutaneous nerve: the nerves to the biceps and brachialis muscle

Hyperselective neurectomy in the treatment of elbow and wrist spasticity: an anatomical study and incision design

OBJECTIVE

Hyperselective neurectomy is used to treat spastic arm paralysis. The aim of the study was to analyze the nerve branching patterns of elbow and wrist flexors/pronator to inform hyperselective neurectomy approached.

METHODS

Eighteen upper extremities of fresh cadaver specimen were dissected. The number of motor branches from the musculocutaneous nerve to biceps brachii and brachialis, median nerve to pronator teres, flexor carpi radialis and ulnar nerve to flexor carpi ulnaris were counted. The origin site of each primary motor branch was documented.

RESULTS

Either biceps or brachialis was innervated by one or two primary motor branches. Pronator teres was innervated by one to three motor trunks and the pattern for flexor carpi radialis was a common trunk with other branches. The origin of the biceps and brachialis nerve trunk was located approximately 30% to 60% of the length of the arm. The median nerve branched to pronator teres and flexor carpi radialis at the region about 34mm (SD 18.8mm) above and 50mm (SD 14.9mm) below the medial epicondyle. Flexor carpi ulnaris was innervated by one to three motor trunks and the mean distance from the medial epicondyle to the origin of flexor carpi ulnaris nerve on ulnar nerve was 18.7 mm (SD 6.5mm).

CONCLUSION

Primary motor branches to elbow flexors, wrist flexors and pronators were various, while the regions of their origins were relatively settled. It was recommended the incisions be designed according to the location of the primary motor trunks.

[Anatomical variants of the median and musculocutaneous nerve - a case report]

Traumatische Schädigungen des Plexus brachialis resultieren häufig in einer eingeschränkten oder aufgehobenen Flexionsbewegung des Ellenbogens. Die Wiederherstellung dieser Bewegung ist ein wichtiges Ziel der chirurgischen Therapie 1 2. Maßgeblich für die Flexionsbewegung und Innervation der Zielmuskeln ist der N. musculocutaneus (MSC). Dieser bildet einen der beiden Endäste des Fasciculus lateralis des Plexus brachialis (C5-C7). In den meisten Fällen verläuft er an der ventralen Oberarmseite, in der Flexorenloge, zwischen dem M. brachialis und M. biceps brachii nach distal und gibt Äste zur motorischen Innervation der beiden Muskeln ab. Er verläuft anschließend durch den Sulcus bicipitalis lateralis und durchbricht die Fascia brachii in der Ellenbeuge 3 um als Nervus cutaneus antebrachii lateralis, sensibel den Unterarm zu versorgen. Variable Verläufe des Plexus brachialis in Zusammenschau mit dem N. musculocutaneus sind beschrieben und können auf vielseitige Art und Weisen imponieren 4 5. So kann der N. musculocutaneus direkte Verbindungen zum N.medianus aufweisen, oder diesen als direkter dritter Zuschuss anteilweise bilden. Der N. medianus kann also sowohl Äste an den N. musculocutaneus abgeben als auch solche von diesem erhalten. Vorliegende Kadaverstudien zeigen in über 50+% der Fälle Verbindungen zwischen dem N. musculocutaneus und dem N. medianus, wobei ein Großteil solcher Verbindungen proximal des Eintrittes des N. musculocutaneus in den M. coracobrachialis liegt 6. Trotzdem sind diese Variationen im klinischen Alltag meist Zufallsbefunde bei chirurgischen Interventionen 7.

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.

Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation of the Musculocutaneous Nerve for Refractory Antecubital ElbowPain-Brief Technical Report and Illustrative Case Report

Chronic pain following distal biceps rupture (DBR) is often nonspecific in that it may arise due to the injury, subsequent surgical repair, or a combination of factors, making the painful symptoms challenging to treat. Peripheral nerve injury in the setting of DBR most commonly affects the musculocutaneous nerve or one of its terminal branches and may lead to chronic neuropathic pain involving the elbow and lateral/radial aspect of the forearm. In this brief technical report, we describe an ultrasound-guided (USG) technique for percutaneous implantation of a peripheral nerve stimulator (PNS) targeting the musculocutaneous nerve, along with an illustrative case report of successful treatment of chronic refractory pain following DBR utilizing this technique. Six months postimplantation, the patient reported a greater than 60% baseline pain intensity reduction, and no complications were noted.

Anatomic Variations of the Musculocutaneous Nerve and Clinical Implications for Restoration of Elbow Flexion

PURPOSE

The restoration of elbow flexion is of primary importance in the management of patients with brachial plexus injuries. Superior functional outcomes via fascicle transfer from the ulnar and median nerves have resulted in this transfer being considered the mainstay of recovery of elbow flexion in patients with intact C8 and T1 function. An understanding of the anatomy of the musculocutaneous nerve (MCN) and its branching pattern is key while performing these transfers.

METHODS

A prospective cohort study was conducted in patients who underwent nerve transfer for the restoration of elbow flexion following a traumatic brachial plexus injury. The anatomic course and branching pattern of the MCN were recorded in eligible cases, both as a line diagram and using intraoperative photographs.

RESULTS

One hundred fifty patients underwent nerve transfer for the restoration of elbow flexion following an injury to the brachial plexus. The MCN in 138 patients (92%) was found to pierce the coracobrachialis muscle before emerging lateral to it. One hundred thirty-four patients (89.3%) demonstrated the "classical" anatomy. One hundred fifteen patients (76.6%) had a single primary branch to the biceps, whereas 25 patients (16.6%) demonstrated a discrete motor branch to each head. One hundred thirty-three dissections (88.6%) revealed a single muscular branch to the brachialis arising posteromedially from the MCN, distal to the origin of the branch to the biceps brachii. Notable unreported variations, such as the MCN penetrating the biceps as it descended, multiple brachialis branches, and trifurcation of divisions of the MCN, were documented.

CONCLUSIONS

Variations in MCN anatomy are quite common, and even unreported variations can be encountered.

CLINICAL RELEVANCE

Exploration of the MCN and its branches for nerve transfers requires knowledge of these anatomic variations and vigilance to prevent inadvertent injuries while dissecting them for nerve transfer surgery.

The innervation of the biceps brachii and brachialis muscles in specimens with a high incidence of an accessory biceps head

We describe the patterns of motor branches to the elbow flexors in 106 fresh-frozen cadaveric upper extremities from 53 donors of the Latin American mestizo race. We identified a 20% incidence of an accessory biceps head. The innervation patterns to this accessory head were specifically described and added to the Yang classification as Type IV for the biceps and Type III for the brachialis. The patterns arising from the musculocutaneous nerve to the biceps brachii were of Type I in 69%, Type II in 9%, Type III in 7% and Type IV in 11%, and to the brachialis of Type I in 77%, Type II in 11% and Type III in 9%. In 4%, the branches did not originate from the musculocutaneous nerve. We hypothesize that the branch to the accessory biceps head might be considered as a donor for nerve transfer in selected brachial plexus injuries.

Sensorimotor Outcomes of Upper Extremity End-to-Side Nerve Transfers: A Meta-analysis

BACKGROUND

End-to-side nerve transfer (ETSNT) for treatment of peripheral nerve injuries is controversial given the myriad anatomic locations, injury types, and indications. Efficacy of ETSNT remains debated. We hypothesized differences in age, sex, transfer location, and time to surgery influence outcomes.

METHODS

We performed a search of the PubMed database for ETSNT in the upper extremity from 1988 to 2018. Age, sex, transfer location, time to surgery, donor and recipient axons, and strength and sensation outcomes as measured by Medical Research Council scale were extracted from articles. Meaningful recovery was classified as Medical Research Council Grade 3 or greater. Association between meaningful recovery and younger (<25) and older (≥25) patients, injury mechanism, sex, transfer location, donor axons, and recipient axons were calculated using a χ 2 or Fisher exact test. A logistic mixed effect model was used with time to surgery, age (categorical), transfer location, and injury type as a fixed effect, and a random paper effect was included to account for correlation among patients from the same paper.

RESULTS

One hundred fifteen patients from 11 studies were included. Neither age (continuous variable, P = 0.68) nor time to surgery ( P = 0.28) affected meaningful recovery. Injury mechanism, sex, and younger age (<25 vs ≥25 years) were not associated with meaningful recovery. Within the brachial plexus ETSNT demonstrated median M4 ± 1 postoperative strength, with trunks/cords as the primary axon donor ( P = 0.03). The musculocutaneous nerve demonstrated promising but variable results in 31 patients with median strength M3 ± 4. Digital nerves consistently demonstrated meaningful sensory recovery as both donor and recipient axons (15 of 15, 100%). Logistic regression analysis demonstrated that odds of meaningful recovery after ETSNT are significantly greater for transfers within the brachial plexus compared with the distal arm (odds ratio, 41.9; 95% CI, 1.1-1586.7, P = 0.04), but location does not significantly affect meaningful recovery ( P = 0.22).

CONCLUSIONS

Patients undergoing ETSNT for digital nerve injury demonstrated meaningful recovery. End-to-side nerve transfer seems to be more efficacious when performed within the brachial plexus. This study did not find sex, injury mechanism, or time to surgery to significantly affect meaningful recovery. Additional study is needed to better evaluate the effectiveness of ETSNT in the upper extremity.

[Modification of intercostobrachial neurotization of musculocutaneous and axillary nerves in total brachial plexopathy: description of technique and literature review]

BACKGROUND

Intercostobrachial neurotization is one of the few approach for partial motor recovery of extremity in patients with total trauma of brachial plexus. However, direct coaptation with musculocutaneous nerve is often impossible due to different anatomy of intercostal nerves and their functional failure at several levels. This necessitates the use of intermediate graft that deteriorates the final outcome.

OBJECTIVE

To develop an alternative method for direct coaptation of musculocutaneous nerve with insufficiently long intercostal donor nerves.

MATERIAL AND METHODS

The study included 26 patients with total post-traumatic plexitis. All patients underwent intercostobrachial neurotization of musculocutaneous and axillary nerves. Original technique of direct selective neurotization of motor fascicular groups of musculocutaneous and axillary nerves was used in 11 cases.

RESULTS AND DISCUSSION

A modified variant of intercostobrachial neurotization of musculocutaneous and axillary nerves consists in mobilization and transposition of recipient nerves in axillary region. This makes it possible to reduce the distance to donor nerves and, in most cases, to carry out direct neurotization without autologous grafts. Among 11 patients, restoration of shoulder abduction and elbow flexion was obtained in 7 patients (77 %).

CONCLUSION

The proposed adaptive technique makes it possible to avoid graft lengthening in some cases and provides satisfactory results.

Nerve Graft Length and Recovery of Elbow Flexion Muscle Strength in Patients With Traumatic Brachial Plexus Injuries: Case Series

BACKGROUND

Traumatic brachial plexus injuries cause long-term maiming of patients. The major target function to restore in complex brachial plexus injury is elbow flexion.

OBJECTIVE

To retrospectively analyze the correlation between the length of the nerve graft and the strength of target muscle recovery in extraplexual and intraplexual nerve transfers.

METHODS

A total of 51 patients with complete or near-complete brachial plexus injuries were treated with a combination of nerve reconstruction strategies. The phrenic nerve (PN) was used as axon donor in 40 patients and the spinal accessory nerve was used in 11 patients. The recipient nerves were the anterior division of the upper trunk (AD), the musculocutaneous nerve (MC), or the biceps branches of the MC (BBs). An index comparing the strength of elbow flexion between the affected and the healthy arms was correlated with the choice of target nerve recipient and the length of nerve grafts, among other parameters. The mean follow-up was 4 yr.

RESULTS

Neither the choice of MC or BB as a recipient nor the length of the nerve graft showed a strong correlation with the strength of elbow flexion. The choice of very proximal recipient nerve (AD) led to axonal misrouting in 25% of the patients in whom no graft was employed.

CONCLUSION

The length of the nerve graft is not a negative factor for obtaining good muscle recovery for elbow flexion when using PN or spinal accessory nerve as axon donors in traumatic brachial plexus injuries.

Anterior minimally invasive plating osteosynthesis technique (MIPO) for humeral shaft fractures: an anatomical study of neuromuscular structures at risk

OBJECTIVE

The aim of this study was to evaluate the neuromuscular structures at risk during modified anterior minimally invasive plating osteosynthesis technique (Belangero-Livani) for humeral shaft fractures.

METHODS

Eight fresh-frozen human specimens ranging from 38 to 82 years old were used. Specimens were positioned supine with the shoulder in 70° abduction and the forearm in full supination. Anterior minimally invasive plating osteosynthesis technique according to Belangero-Livani technique was performed in each specimen. Under radioscopic control, the plate was introduced in retrograde fashion through the subbrachialis path. Anatomical structures were inspected and different anatomical parameters were measured after dissection at the end of the surgical procedures. Measurements were performed using a high digital caliper. Statistical analysis was performed using the Pearson's correlation coefficient test. A p value of < 0.05 was used to define statistical significance.

RESULTS

There were no macroscopic lesions of myotendinous or neurovascular structures in any specimen. The mean distance between the radial nerve to the distal lateral end of the plate was 8.63 mm (range 4.14-13.83 mm). The mean total length of the humerus was 328.59 mm. We found a significant direct correlation between the total length of the humerus and both specimen height and weight.

CONCLUSION

The modified Belangero-Livani anterior MIPO technique for humeral shaft fractures performed in retrograde fashion is safe and useful, without major risk to the soft tissue of the anterior compartment of the arm, including the radial nerve in the lateral intermuscular septum. Intraoperative dissection, avoiding deep lateral retraction on the distal approach, minimizes the risk of radial nerve damage. Strict surgical planning and appreciation for the anatomic landmarks can reduce the risk of damage to neuromuscular structures.

LEVEL OF EVIDENCE

Level IV; Case series with no comparison group; Treatment study.

Treatment methods for post-traumatic elbow stiffness caused by heterotopic ossification

HYPOTHESIS

Heterotopic ossification (HO) is a common complication of surgically treated elbow fractures that can inhibit range of motion and impair quality of life. Although there are many treatment methods for HO, there is a lack of consensus as to the best option. We hypothesized that contracture release combined with Botox injection would lead to improved functional outcome scores when compared with current treatment methods.

METHODS

A retrospective review was conducted of patients who presented to a single surgeon with HO secondary to elbow fracture between 2005 and 2018. A total of 59 patients were identified who met inclusion criteria. Data were classified into 3 groups: contracture release (control - CR), Botox injection with CR (Botox + CR), and radiation therapy with CR (CR + RT). Range of motion measurements were obtained, including flexion, extension, pronation, and supination.

RESULTS

A total of 30 patients (30 of 59, 50.8%) received CR, 6 (6 of 59, 9.2%) were treated with CR + RT, and 23 (23 of 59, 40.0%) had CR + Botox. There was a significant difference between pre- and postoperative arc of motion for both CR + RT (P < .01) and CR + Botox (P < .01). In addition, there was a significant difference in pre- and postoperative extension for patients who received intraoperative Botox injections (P < .05). There was no significant difference between pre- and postoperative motion nor extension in the CR group.

CONCLUSION

Intraoperative Botox injection with CR is an effective method in the treatment of post-traumatic elbow stiffness caused by HO.

Open reduction and internal fixation of humeral midshaft fractures: anterior versus posterior plate fixation

Background

Fractures of the humeral shaft represent 2–4% of all fractures. Fractures of the humerus have traditionally been approached posteriorly for open reduction and internal fixation. Reports of treating midshaft fractures with an open anterolateral approach and anterior plating are limited. The purpose of this study was to evaluate a series of humeral shaft fractures treated with plate osteosynthesis regarding the effect of the approach and plate location on the healing rate and occurrence of complications.

Methods

We conducted a retrospective chart review of patients aged over 18 years with humeral midshaft fractures treated with anterior or posterior plate fixation. Selection of the approach to the humerus was based on the particular pattern of injury and soft tissue involvement. The minimum follow-up duration was set at six months. The outcomes included the rate of union, primary nerve palsy recovery, secondary nerve damage, infection and revision surgery.

Results

Between 2006 and 2014, 58 patients (mean age, 59.9; range, 19–97 years) with humeral midshaft fractures were treated with anterior (n = 33) or posterior (n = 25) plate fixation. After a mean follow-up duration of 34 months, 57 of 58 fractures achieved union after index procedure. Twelve fractures were associated with primary radial nerve palsy. Ten of the twelve patients with primary radial palsy recovered completely within six months after the index surgery. In total, one patient developed secondary palsy after anterior plating, and three patients developed secondary palsy after posterior plating. No significant difference in the healing rate (p = 0.4), primary nerve palsy recovery rate (p = 0.6) or prevalence of secondary nerve palsy (p = 0.4) was found between the two clinical groups. No cases of infection after plate fixation were documented.

Conclusions

Open reduction and internal fixation using an anterior approach with plate fixation provides a safe alternative to posterior plating in the treatment of humeral shaft fractures. An anterior approach allows supine positioning of the patient and yields union and complication rates comparable to those of a posterior approach with plate fixation for the treatment of humeral shaft fractures.

Re-visiting the brachialis muscle: morphology, morphometry, gender diversity, and innervation

PURPOSE

The brachialis (BM) is a complex muscle with a long-running controversy regarding its morphology and innervation. The primary objective of this study was to elucidate the detailed gross morphology of BM in an adult Sri Lankan population.

METHOD

Cadaveric upper limbs (n = 240) were examined for the proximal and distal attachments, length, width, thickness of BM, and innervations by the musculocutaneous (MCN) and radial nerve (RN).

RESULTS

In all cases, the BM consisted of two heads: superficial head (SHB) and deep head (DHB). Proximally SHB and DHB originated from the lateral, anterior, and medial aspects of the middle and distal thirds of the shaft of the humerus and inserted onto the coronoid process and the tuberosity of ulna, respectively, as two separate entities. Statistically significant (P < 0.05) gender differences were observed between the mean values (mm) of muscle length (male: 188.03 ± 10.54; female: 166.14 ± 7.97), width (male: 26.57 ± 4.80; female: 25.28 ± 4.67), thickness (male: 10.73 ± 1.74; female: 9.74 ± 1.28), and tendon length (male: 44.44 ± 7.73; female: 33.40 ± 5.09). In all cases, MCN innervated the BM, while the model site of piercing was in the middle third of the muscle. The incidence of RN contribution to BM was 83.33% and in the vast majority it pierced the inferior third of the BM.

CONCLUSION

Present study provides a comprehensive anatomical overview of the BM. An in-depth knowledge of the anatomy of BM may aid in comprehending functional characteristics, enhance the accuracy of imaging modalities, and provide new insight to the current surgical approaches around the elbow joint which in turn will invariably minimize the potential complications encountered during clinical procedures.

Nerve transfers for peripheral nerve injury in the upper limb: a case-based review

Nerve transfer has become a common and often effective reconstructive strategy for proximal and complex peripheral nerve injuries of the upper limb. This case-based discussion explores the principles and potential benefits of nerve transfer surgery and offers in-depth discussion of several established and valuable techniques including: motor transfer for elbow flexion after musculocutaneous nerve injury, deltoid reanimation for axillary nerve palsy, intrinsic re-innervation following proximal ulnar nerve repair, and critical sensory recovery despite non-reconstructable median nerve lesions.

Prevalence of musculocutaneous nerve variations: Systematic review and meta-analysis

We aimed to establish the prevalence of the musculocutaneous nerve (MCN) variations and the probability of the variation being pure or mixed in the same plexus. We applied the principles of evidence-based anatomy to find, appraise, and synthesize data through a meta-analysis of anatomical studies. The variations were grouped based on the presence and location of the communicating branch with the median nerve and the origin of branches to anterior arm muscles. Forty-three cadaveric studies met the inclusion criteria, providing data from 4124 plexuses. The overall pooled prevalence of plexuses with MCN variations was 20%. Based on the classification applied in our study, the pooled prevalence of variations was 17% in region 1A, 20% in region 1B, 36% in region 2 and 49% in region 3. Importantly, 64.58% of variations in region 1A and 74.14% of variations in region 1B were mixed, that is, associated with a variation in another region. The odds of finding another variation in the presence of a variation in region 2 or 3 were equal 0.37 and 0.52, respectively, demonstrating a significantly lower probability of finding mixed variations involving these regions, when compared with region 1A. Variations of the MCN are most common in the part distal to the exit from within or beneath the coracobrachialis muscle. Proximal variations are more often associated with another variation located along the nerve. These findings can assist health care professionals in the treatment of brachial plexus lesions. Clin. Anat. 32:183-195, 2019. © 2018 Wiley Periodicals, Inc.

Variants of latissimus dorsi with a perspective on tendon transfer surgery: an anatomic study

BACKGROUND

The latissimus dorsi (LD) is often used for tendon transfers to treat massive irreparable posterosuperior rotator cuff tears. The operation requires the LD tendon to be mobilized to reduce tension on the tendon. In that respect, any connection between the LD tendon and contiguous muscles may hamper tendon mobility and affect the surgical outcome. The goal of this study was to document the occurrence of connections between the LD and adjacent muscles and nerves.

METHODS

We studied the scapular region on 48 embalmed cadavers. The skin and superficial fascia were removed according to Cunningham's manual of dissection, and the muscle was exposed.

RESULTS

It was found that the LD and teres major (TM) muscles are connected by muscle fibers in 10% of the cadavers studied. Another vital discovery was that in some cadavers, the LD tendon was penetrated by a nerve.

CONCLUSION

Fascial connections between the LD and TM are well known, but these muscle links are comparatively unusual. From the results of this study, one should pay particular attention to muscle links between the LD and TM during dissection of the LD for transfer. It can also be suggested that during transfer surgery, the LD tendon should be cautiously examined for the possibility of a nerve penetrating it.

Targeted Muscle Reinnervation of the Brachium: An Anatomic Study of Musculocutaneous and Radial Nerve Motor Points Relative to Proximal Landmarks

PURPOSE

Targeted muscle reinnervation (TMR) offers enhanced prosthetic use by harnessing additional neural control from unused nerves in the amputated limb. The purpose of this study was to document the location and number of motor end plates to each muscle commonly used in TMR in the brachium relative to proximally based bony landmarks.

METHODS

We dissected 18 matched upper limbs (9 fresh-frozen cadavers). The locations of each of the nerves' muscular insertions into the medial biceps and brachialis were measured relative to the anterolateral tip of the acromion. The terminal branches to the lateral triceps were measured relative to the posterolateral tip of the acromion. Both the number of branches and the location of the muscular insertions were documented. Common descriptive statistics were used to describe the data.

RESULTS

There was a median of 2 branches to the medial biceps located 19.6 cm from the anterolateral tip of the acromion (range, 15-25 cm). There was a median of 3.5 branches to the brachialis located 24.2 cm from the anterolateral tip of the acromion (range, 19-27.5 cm). There was a median of 2.5 branches to the lateral triceps located 21.6 cm from the posterolateral tip of the acromion (range, 11-29 cm). The mean distances to the primary branch muscle and the number of smaller branches were not significantly different when compared by sex or side.

CONCLUSIONS

Motor points for the medial biceps, brachialis, and lateral triceps can be identified reliably using proximal landmarks in targeted muscle reinnervation.

CLINICAL RELEVANCE

The data obtained from this study may assist the surgeon in localizing the nerve branches and muscular insertions for the commonly used muscles for TMR of the brachium.

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.

Communication between the musculocutaneous and median nerves in the arm: an anatomical study and clinical implications

Objective

To determine the frequency and features of communication between the musculocutaneous nerve (MCN) and median nerve (MN) in a sample of the Colombian population, and assess its clinical implication.

Methods

The arms of 53 cadaver specimens that had been subjected to necropsy at the National Institute of Forensic Medicine, in Bucaramanga, Colombia, were studied. The structures of the anterior compartment of the arm were dissected and characterized regarding the presence of communication between the MCN and MN.

Results

A communicating branch was found in 21/106 upper limbs (19.8%), occurring bilaterally in 10 (47.6%) and unilaterally in 11 (52.4%), without significant difference regarding the side of occurrence (p = 0.30). In 17% of the cases, there was MCN-MN communication in which the communicating branch was seen leaving the MCN after piercing the coracobrachialis muscle (Type I). In 2.8%, the connection was from the MN to the MCN (Type II). The length of the communicating branch was 57.8 ± 33.4 mm. The distances from the proximal and distal points of this branch to the coracoid process were 138 ± 39.4 mm and 188 ± 48.3 mm, respectively. The communicating branch was located mostly in the middle third of the arm.

Conclusions

The frequency of MCN-MN communication observed in the present study is in the middle of the range of what was reported in previous studies. MCN-MN connections need to be taken into account in diagnosing and managing peripheral nerve lesions of the upper limbs.

Anatomical Study of the Ulnar Nerve Variations at High Humeral Level and Their Possible Clinical and Diagnostic Implications

Background. Descriptive evaluation of nerve variations plays a pivotal role in the usefulness of clinical or surgical practice, as an anatomical variation often sets a risk of nerve palsy syndrome. Ulnar nerve (UN) is one amongst the major nerves involved in neuropathy. In the present anatomical study, variations related to ulnar nerve have been identified and its potential clinical implications discussed. Materials and Method. We examined 50 upper limb dissected specimens for possible ulnar nerve variations. Careful observation for any aberrant formation and/or communication in relation to UN has been carried out. Results. Four out of 50 limbs (8%) presented with variations related to ulnar nerve. Amongst them, in two cases abnormal communication with neighboring nerve was identified and variation in the formation of UN was noted in remaining two limbs. Conclusion. An unusual relation of UN with its neighboring nerves, thus muscles, and its aberrant formation might jeopardize the normal sensori-motor behavior. Knowledge about anatomical variations of the UN is therefore important for the clinicians in understanding the severity of ulnar nerve neuropathy related complications.

Transfer of the brachialis to the anterior interosseous nerve as a treatment strategy for cervical spinal cord injury: technical note

Study Design Technical report. Objective To provide a technical description of the transfer of the brachialis to the anterior interosseous nerve (AIN) for the treatment of tetraplegia after a cervical spinal cord injury (SCI). Methods In this technical report, the authors present a case illustration of an ideal surgical candidate for a brachialis-to-AIN transfer: a 21-year-old patient with a complete C7 spinal cord injury and failure of any hand motor recovery. The authors provide detailed description including images and video showing how to perform the brachialis-to-AIN transfer. Results The brachialis nerve and AIN fascicles can be successfully isolated using visual inspection and motor mapping. Then, careful dissection and microsurgical coaptation can be used for a successful anterior interosseous reinnervation. Conclusion The nerve transfer techniques for reinnervation have been described predominantly for the treatment of brachial plexus injuries. The majority of the nerve transfer techniques have focused on the upper brachial plexus or distal nerves of the lower brachial plexus. More recently, nerve transfers have reemerged as a potential reinnervation strategy for select patients with cervical SCI. The brachialis-to-AIN transfer technique offers a potential means for restoration of intrinsic hand function in patients with SCI.

Biceps muscle fatty infiltration and atrophy. A midterm review after arthroscopic tenotomy of the long head of the biceps

PURPOSE

Pathology of the long head of the biceps (LHB) tendon is commonly treated by tenotomy. High levels of clinical function and patient satisfaction are reported in the short-term. The purpose of this study was to investigate the midterm effects of tenotomy on biceps fatty infiltration and atrophy in active working-age male patients.

METHODS

Twenty-five men (mean age, 57 years) were evaluated at a mean follow-up of 6.7 years after tenotomy. Bilateral magnetic resonance imaging (MRI) was performed, and fatty infiltration of the biceps was assessed relative to the ipsilateral triceps. Seventeen participants had an intact contralateral LHB tendon. To assess atrophy, anterior muscle compartment volume was measured by serial cross-sectional area measurements on MRI. The tenotomized side was then compared to the healthy side in these 17 participants. Clinical scores were obtained using the QuickDASH and Oxford Elbow Score, and the occurrence of a Popeye sign and residual pain were recorded.

RESULTS

Good clinical function was maintained at a mean follow-up time of 6.7 years (range, 4 to 10 years) (QuickDASH score of 7.1; standard error [SE], 1.8) and Oxford Elbow Score of 97.9 [SE 1.2]). Eleven of the 25 participants had a Popeye deformity. Four participants showed signs of fatty infiltration, and all were minor (grade 1). The mean decrease in total volume of the anterior musculature was 3.6%. In participants without a Popeye deformity, it was 3.3%, whereas it was 4.1% in participants with a Popeye sign (P = .8).

CONCLUSIONS

In the midterm, LHB tenotomy in active men of working age does not result in fatty degeneration or substantial atrophy in the anterior musculature of the arm. Clinical function remains good.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Subbrachial approach to humeral shaft fractures: new surgical technique and retrospective case series study

BACKGROUND

There are few surgical approaches for treating humeral shaft fractures. Here we present our results using a subbrachial approach.

METHODS

We conducted a retrospective case series involving patients who had surgery for a humeral shaft fracture between January 1994 and January 2008. We divided patients into 4 groups based on the surgical approach (anterior, anterolateral, posterior, subbrachial). In all patients, an AO 4.5 mm dynamic compression plate was used.

RESULTS

During our study period, 280 patients aged 30-36 years underwent surgery for a humeral shaft fracture. The average duration of surgery was shortest using the subbrachial approach (40 min). The average loss of muscle strength was 40% for the anterolateral, 48% for the posterior, 42% for the anterior and 20% for the subbrachial approaches. The average loss of tension in the brachialis muscle after 4 months was 61% for the anterolateral, 48% for the anterior and 11% for the subbrachial approaches. Sixteen patients in the anterolateral and anterior groups and 6 patients in the posterior group experienced intraoperative lesions of the radial nerve. No postoperative complications were observed in the subbrachial group.

CONCLUSION

The subbrachial approach is practical and effective. The average duration of the surgery is shortened by half, loss of the muscle strength is minimal, and patients can resume everyday activities within 4 months. No patients in the subbrachial group experienced injuries to the radial or musculocutaneous nerves.

Subpectoral biceps tenodesis: an anatomic study and evaluation of at-risk structures

BACKGROUND

The neurovascular structures of the proximal arm may be at risk for iatrogenic injury during open subpectoral biceps tenodesis (OSPBT).

PURPOSE

To define the anatomic relationships and at-risk structures during OSPBT and to quantify the effect of arm rotation on the position of the musculocutaneous nerve.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The OSPBT approach was performed in 17 unembalmed cadaveric upper extremities. The tenodesis site was inferior to the bicipital groove and positioned so the musculotendinous portion of the long head of the biceps rested at the inferior border of the pectoralis major. A meticulous dissection identified the brachial artery, deep brachial artery, cephalic vein, brachial vein, medial brachial cutaneous nerve, medial antebrachial cutaneous nerve, intercostal brachial cutaneous nerve, musculocutaneous nerve, axillary nerve, median nerve, and radial nerve. Superficial structures were measured from the superior and inferior aspects of the incision, and deep structures were measured from the tenodesis site and nearest retractor. The musculocutaneous nerve was measured with the arm in neutral, internal, and external rotation.

RESULTS

The musculocutaneous nerve was 10.1 mm (range, 6-18 mm) medial to the tenodesis location and 2.9 mm (range, 1-6 mm) medial to the medially placed retractor in neutral arm position. The radial nerve and deep brachial artery were 7.4 mm (range, 2-12 mm) and 5.7 mm (range, 1-10 mm) deep to the medially placed retractor, respectively. With the arm internally rotated to 45°, the musculocutaneous nerve was 8.1 mm from the tenodesis site, compared with 19.4 mm with the arm 45° externally rotated (P = .009). The median nerve, brachial artery, and brachial vein were >2.5 cm from the tenodesis site and nearest retractor during deep dissection.

CONCLUSION

The musculocutaneous nerve, radial nerve, and deep brachial artery are within 1 cm of the standard medial retractor. External rotation of the arm moves the musculocutaneous nerve 11.3 mm further away from the tenodesis site compared with the internally rotated position.

CLINICAL RELEVANCE

The musculocutaneous nerve, radial nerve, and deep brachial artery course in close proximity to the operative field and are therefore at risk during OSPBT. Limiting the use of medial retraction and placement of the arm in an externally rotated position will minimize neurovascular injury.

Surface mapping of motor points in biceps brachii muscle

Objective

To localize the site of motor points within human biceps brachii muscles through surface mapping using electrophysiological method.

Method

We recorded the compound muscle action potentials of each lattice of the biceps brachii in 40 healthy subjects. Standardized reference lines were made as the following: 1) a horizontal reference line (elbow crease) and 2) a vertical reference line connecting coracoid process and mid-point of the horizontal reference line. The Compound muscle action potentials were mapped in reference to the standardized reference lines. The locations of motor points were mapped to the skin surface, in the ratio to the length of the vertical and the half of the horizontal reference lines.

Results

The motor point of the short head of biceps was located at 69.0±4.9% distal and 19.1±9.5% medial to the mid-point of horizontal reference line. The location of the motor point of the long head of the biceps was 67.3±4.3% distal and 21.4±8.7% lateral. The motor point of the short head of the biceps was located more medially and distally in the male subjects compared to that in the female (p<0.05).

Conclusion

This study showed electrophysiological motor points of the biceps brachii muscles through surface mapping. This data might improve the clinical efficacy and the feasibility of motor point targeting, when injecting botulinum neurotoxin in biceps brachii.

Patterns of motor branching of the musculocutaneous nerve in human fetuses and clinical significance

The purpose of this morphologic study is to investigate the course and the branching pattern of motor branches of musculocutaneous nerve (MCN) in human fetuses. Twenty upper limbs (10 right, 10 left) of spontaneously aborted formalin-fixed fetuses were dissected under a stereomicroscope to determine motor branches for the biceps brachii and brachialis and the communicating branches between the MCN and median nerve (MN). The MCN entered the proximal and middle part of coracobrachialis in 13/20 and 5/20 of arms, respectively, and the remaining 2/20 did not pierce coracobrachialis. The communication between MCN and MN was observed in 5/20 of the arms and detected only in the distal part of the coracobrachialis. The most frequently observed innervation is the type wherein a single branch to biceps brachii, which bifurcated for supplying the short and long heads (12/20). For the innervation of brachialis, the most frequent type was a single branch from the main trunk of the MCN (15/20). During the dissections, the distance between the acromion and the emerging point of the motor branches was measured. The mean distance between the acromion and the emerging point of the all motor branches for biceps brachii in all types of specimens was 33.8 ± 6.1% of acromion-lateral epicondyle length and for brachialis was 50.6 ± 11.5% of acromion-lateral epicondyle length. The data of the MCN variations in the human fetus may be useful for the clinicians and pediatric surgery.

Anatomic study in cadaver of the motor branch of the musculocutaneous nerve

This study of 80 cadavers demonstrates that the anatomic position of the motor branch of the musculocutaneous nerve with respect to that of the sensitive branch of the same nerve is lateral in more than 88% of cases in humans.The distance from plexus to the separation into the motor and sensitive fascicles was 8-9 cm long.Given the lateral position of the motor component of the musculocutaneous nerve, the nerves that are going to be used to neurotize this area can be directed so as to increase the efficacy of the results for the flexor function of the arm.

INTRODUCTION

Brachial plexus lesions produce great morbidity and are relatively frequent in young adults. Innervating the coracobrachial, biceps and anterior brachial muscles, the musculocutaneous nerve is one of the priorities for nerve neurotization when plexus root avulsion occurs because it is essential for arm flexion. This nerve has both a motor and sensitive component, and the anatomic positions of the two components have not been much studied. When performing a neurotization anastomosis to the musculocutaneous nerve, being able to identify the motor component of the graft and attach it to the motor component of the musculocutaneous nerve could avoid a loss of many motor axons which would otherwise occur if the graft were attached to the sensitive component.

OBJECTIVE

The present paper is based on a topographic anatomic study to locate and obtain the objective positioning of the motor branch of the musculocutaneous nerve in humans, as well as measure its length from the origin in the brachial plexus to the separation of both fascicles into branches.

MATERIAL AND METHODS

The study was performed in 40 cadavers, dissecting the musculocutaneous nerve along its course and measuring the distance from its emergence from the plexus until the separation between its motor and sensitive branches in both arms so as to be able to determine the positioning of the motor fascicle with respect to the sensitive fascicle.

RESULTS

The distance from plexus to the separation into the motor and sensitive fascicles was 8.8 cm on the left side and 8.95 cm on the right side. The position of the motor branch with respect to the sensitive branch was lateral in more than 85% of the studied nerves, all the way from its origin in the brachial plexus until the definitive separation between both branches, on both the right and the left sides.

CONCLUSION

If the nerves that are to be used for neurotization of the musculacutaneous nerve are directly taken to the lateral fascicle of that nerve, which is generally the motor component, the treatment should be effective and should avoid the loss of motor axons resulting from anastomosing to the sensitive fascicle.

A comparative microanatomical study on cross sections of medial and lateral cutaneous nerves of forearm at the antecubital fossa: a cadaveric study

BACKGROUND

The anterior branch of the medial antebrachial cutaneous nerve of the forearm (AMACN) and the lateral antebrachial cutaneous nerve of the forearm (LACN) are used as potential donor grafts for repairing sensory nerves. A higher percentage of connective tissue plays an important role in predicting prognosis after nerve repair. The aim is to perform a comparative study on cross-sectional microanatomy and age related changes in non-fascicular components of the AMACN and LACN.

METHODS

Thirty six fresh human (from both sides of 14 male and 4 female) cadaveric AMACN and LACN were collected at antecubital fossae and studied at different magnifications for morphometric analysis (total cross-sectional area (Asc), fascicular area (Af) and non-fascicular area (Anonf)), after histological (Masson's trichrome stain) processing.

RESULTS

AMACN and LACN belong to polyfascicular type and showed differences in amount of connective and adipose tissues in non-fascicular areas. In the AMACN, there was less adipose tissue (19.38% in Asc and 25.57% in Anonf) with more collagen fibers (57.28% in Asc and 75.57% in Anonf) and in the LACN, there was more adipose tissue (47.51% in Asc and 58.19% in Anonf) with fewer collagen fibers (34.10% in Asc and 41.76% in Anonf) in interfascicular domains.

CONCLUSIONS

The amount of adipose tissue in LACN non-fascicular area was found to be high at all ages. The presence of less adipose tissue and collagen fibers in the non-fascicular area of the AMACN (below 60 years) could be used for successful nerve grafting when compared to LACN.

The course and variations of the branches of the musculocutaneous nerve in human fetuses

The course and branches of the musculocutaneous nerve (MCN) were dissected in 140 human fetal arms. The MCN entered the superior, middle, and inferior part of coracobrachialis in 43%, 37%, and 17% of arms, respectively, and the remaining 3% did not pierce coracobrachialis. The motor branches to biceps were classified as follows: Type 1 (83.6%): a single branch that bifurcated to supply the two heads of biceps; Type 2 (14.3%): two separate branches each innervating one head of biceps; Type 3 (2.1%): a single branch that bifurcated to supply each head of biceps plus an additional branch that innervated the distal part of biceps. The motor branches to brachialis were classified as follows: Type 1 (93.6%): a single branch to brachialis; Type 2 (6.4%): a single branch that bifurcated into two branches both supplying brachialis. Communications between the MCN and the median nerve (MN) were observed in 10% of specimens, of which three types (A, B, C) could be identified depending on their origin and union. In the most frequently observed type (B, 50% of cases) the communicating branch arose from the proximal part of the MCN and joined the MN in the middle or distal part of arm. The data presented here will be of use to surgeons, especially pediatric surgeons who undertake surgical procedures in the axilla and arm.

Anatomy of branches of the musculocutaneous nerve to the biceps and brachialis in human fetuses

Forty upper limbs (20 right and 20 left) of spontaneously aborted human fetuses were examined to determine the branching patterns of the musculocutaneous nerve. The mean age of the fetuses was 21.3 weeks. We identified three branching patterns of the musculocutaneous nerve to the biceps muscle. Type I with a single primary branch occurred in 47.5% of cases. Type II with two primary branches each to a separate head of the biceps muscle was observed in 42.5% of cases. Type III consisted of two primary branches, the proximal dividing into two branches, each to a different head of the biceps, and the distal branch supplying the common belly. Type III was present in 10% of cases. We found only one branching pattern for the brachialis muscle, a single primary branch. In our material communicating branches between the median and musculocutaneous nerves were found in 20% of specimens. We measured the distances between the acromion and the exit points of the first and second branch to the biceps, which averaged 36.3% for the first branch regardless of the type of branching pattern, 54.2% for the second branch in Type II, 60.7% for the second branch in Type III and 60.9% for the branch to brachialis, expressed as a percentage of the distance between the acromion and the lateral epicondyle.

[Minimally invasive fixed-angle plate osteosynthesis for complex humeral fracture]

Two cases of complex humeral fractures are presented that were stabilised by a minimally invasive approach using a long fixed-angle humerus plate. Postoperative treatment and bone healing were uneventful. Followed by careful preparation of a proximal deltoid split access and a subtle dissection of the m. brachialis the plate can be placed epiperiosteally and the screws can be applied using the"moving window" principle. Fixed-angle fixation with the internal fixator principle allows treating the radial nerve in the direct neighbourhood of the plate with circumspect without full contact between the bone and the plate. The technique can be recommended for complex combined meta- and diaphyseal fractures of the upper two-thirds of the humerus.

Relocation of neuromas of the lateral antebrachial cutaneous nerve of the forearm into the brachialis muscle

Painful neuromas following injury to the radial side of the wrist can be treated by relocation away from the zone of injury and implantation into muscle. Relocation to the brachialis muscle is useful for isolated neuromas of the lateral antebrachial cutaneous nerve and involves a shorter dissection than relocation to the brachioradialis. It is also useful in patients undergoing multiple procedures to avoid disturbing previous relocations to the brachioradialis. This paper describes the successful relocation of painful neuromas of the lateral antebrachial cutaneous nerve to the brachialis muscle in seven patients.

Difference in Recovery Potential of Peripheral Nerves after Graft Repairs

OBJECTIVE:

To our knowledge, few studies have been published regarding differences in nerve recovery potentials. In this study, sensory and motor recovery potentials were compared between different nerves.

METHODS:

A prospective study of a homogenous group of 393 graft repairs of the median, ulnar, radial, tibial, peroneal, femoral, and musculocutaneous nerves, with the scoring of motor and sensory recoveries. Sensory and motor recovery potentials, defined on the basis of average scores and rates of useful recovery, were compared between the different nerves, and separately for high-, intermediate-, and low-level repairs.

RESULTS:

Sensory recovery potential was similar for all nerves tested (P &gt; 0.05), but motor recovery potential differed significantly. After high-level repairs, motor recovery potential was significantly better for the radial and tibial nerves (useful recovery in 66.7 and 54.5% of patients, respectively), than for the ulnar and peroneal nerves (useful recovery in 15.4 and 13.8% of patients, respectively; P &lt; 0.05). After intermediate-level repairs, motor recovery potential was better for the musculocutaneous, radial, and femoral nerves (useful recovery in 100, 98.3, and 87.5% of repairs, respectively), than for the tibial, median and ulnar nerves (useful recovery in 63.9, 52, and 43.6% of repairs, respectively; P &lt; 0.05). In addition, motor recovery potential was significantly the worst with peroneal nerve repairs (useful recovery in 15.2% of patients; P &lt; 0.05). After low-level repairs, motor recovery potential was similar for all nerves (useful recovery in the range of 88.9–100% of patients and in 56.3% of peroneal nerve repairs).

CONCLUSION:

Sensory recovery potential is similar for the median, ulnar, and tibial nerves. The expression of motor recovery potential depends on the repair level. With low- and high-level repairs, it does not stand out in an obvious way, but it is fully expressed with intermediate-level repairs, classifying nerves into three categories with excellent, moderate, and poor recovery potential.

Brachialis muscle transfer to reconstruct finger flexion or wrist extension in brachial plexus palsy

PURPOSE

Tendon transfers are a routine procedure used to improve hand function in brachial plexus injuries; however, muscles from forearm donors are not always available for transfer. In this situation a distant muscle may be used. This study describes transfer of the brachialis muscle to the forearm muscles to reconstruct finger flexion or wrist extension in patients with brachial plexus injuries.

METHODS

In 6 patients the brachialis muscle was transferred to the flexor digitorum profundus and the flexor pollicis longus to restore finger and thumb flexion with the goal of reconstructing a key pinch and hook grasp. In 3 patients the brachialis muscle was transferred to the extensor carpi radialis brevis to restore wrist extension. The patients were evaluated at regular intervals and had final assessments between 10 and 12 months after surgery.

RESULTS

Brachialis transfer to the flexor digitorum profundus and the flexor pollicis longus resulted in active motion with full range of digital flexion in the 2 patients who had partial flexion before surgery, and for the 4 patients who had no finger flexion before surgery it resulted in a pulp-to-palm distance for the middle finger of 1 cm in 3 patients and of 2 cm in 1 patient. A lateral key pinch and hook grasp reconstruction was achieved in all patients. Grasping and lateral pinch strengths averaged 110 and 94 mm Hg, respectively. When the brachialis was transferred to the wrist extensors the patients recovered 20 degrees of active wrist extension against resistance.

CONCLUSIONS

Brachialis muscle transfer to the forearm muscle constitutes a valid strategy in the reconstruction of finger and thumb flexion and wrist extension after brachial plexus injury when forearm donor muscles are not available.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic, Level IV.

Helical plating of the proximal humerus

The ideal treatment for fractures of the proximal humerus has not been definitively agreed upon. Several recent reports have described a technique of helical plating for proximal humeral fractures, in which the proximal plate is placed laterally on the greater tuberosity, and spirals 90 degrees distally to lie on the anterior surface of the humeral shaft. The purpose of this study was to evaluate the feasibility of helical plating using a less invasive surgical approach and placing screws percutaneously in the distal plate. Dissection of 10 cadaveric upper extremity specimens was performed, using an extended anterolateral acromial approach followed by percutaneous helical plating. With the plate secured, the neurovascular structures which crossed the anterior humerus superficial to the plate were exposed and identified. Only the musculocutaneous nerve crossed anterior to the plate and was at risk for percutaneous screw placement. The nerve location was found in a consistent location among the specimens. The danger zone for the nerve location was found to be at an average of 13.5 cm from the greater tuberosity (99% CI: 12.2-14.8 cm). Though clinical experience is necessary to validate this plating technique, it appears that avoiding this danger zone in which the musculocutaneous nerve crosses will allow safe percutaneous screw placement and permit minimally invasive plating of these fractures.

Bilateral variant contributions in the formation of median nerve

Bilateral variations in the formation of median nerve (Mn) and the recurrent course of its communications with musculocutaneous nerve (MCn) are very rare. These bilateral anomalies were observed during a routine dissection of the upper limbs of an adult male cadaver in the Department of Anatomy, PGIMER, Chandigarh. On both the sides, Mn was formed by the union of three roots. There was an additional lateral root on both sides. On the right side it was a contribution from the lateral cord and on the left it arose from the anterior division of the middle trunk. On the left side the lateral cord was formed distal than usual in relation to the second part of the axillary artery. On the right side a communicating branch arising from the additional lateral root followed a recurrent course and divided into two to unite separately with medial root of median, while on the left side a single communicating branch from an additional lateral root united with the medial root of median. Recurrent course of the communicating branch between lateral root of median and medial root of median has not been reported earlier. On the right side the MCn after piercing the coracobrachialis gave another communicating branch, which joined the Mn at the level of insertion of deltoid.