A Fresh Cadaver Study on the Innervation of Brachioradialis and Extensor Carpi Radialis Longus Muscles

PURPOSE

Distal nerve transfers have revolutionized peripheral nerve surgery by allowing the transfer of healthy motor nerves to paralyzed ones without causing additional morbidity. Radial nerve branches to the brachialis (Ba), brachioradialis (Br), and extensor carpi radialis longus (ECRL) muscles have not been investigated in fresh cadavers.

METHODS

The radial nerve and its branches were dissected in 34 upper limbs from 17 fresh cadavers. Measurements were taken to determine the number, origin, length, and diameter of the branches. Myelinated fiber counts were obtained through histological analysis.

RESULTS

The first branch of the radial nerve at the elbow was to the Ba muscle, followed by the branches to the Br and ECRL muscles. The Ba and Br muscles consistently received single innervation. The ECRL muscle showed varying innervation patterns, with one, two, or three branches. The branches to the Br muscles originated from the anterior side of the radial nerve, whereas the branches to the Ba and ECRL muscles originated from the posterior side. The average myelinated fiber counts favored the nerve to Br muscle over that to the ECRL muscle, with counts of 542 versus 350 and 568 versus 302 observed in hematoxylin and eosin and neurofilament staining, respectively.

CONCLUSIONS

This study provides detailed anatomical insights into the motor branches of the radial nerve to the Ba, Br, and ECRL muscles.

CLINICAL RELEVANCE

Understanding the anatomy of the radial nerve branches at the elbow is of utmost importance when devising a reconstructive strategy for upper limb paralysis. These findings can guide surgeons in selecting appropriate donor or recipient nerves for nerve transfer in cases of high tetraplegia and lower-type brachial plexus injuries.

Examining the Forearm Intersection through Palpation and Ultrasonography

BACKGROUND

Forearm intersection syndrome causes pain, swelling, and a rub at the dorsal distal forearm where the first extensor compartment muscles intersect with the second compartment tendons. Although primary care settings tend to treat mild cases, high-performance athletes may suffer from severe symptoms that require surgery. This proof-of-concept study aims to help detect the anatomical substrate of forearm intersection syndrome using palpation and ultrasonography when available.

METHODS

Five individuals were studied using independent palpation and ultrasonography to identify the first dorsal compartment muscles and the second dorsal compartment tendons. The distances between the dorsal (Lister's) tubercle of the radius and the ulnar and radial edges of the first dorsal compartment muscles were measured to determine the location and extent of the muscle-tendon intersection. The palpatory and ultrasonographic measurements were compared using descriptive statistics and the paired t-test.

RESULTS

The mean distances from the dorsal tubercle of the radius to the ulnar and radial borders of the first dorsal compartment muscles were 4.0 cm (SE 0.42) and 7.7 cm (SE 0.56), respectively, based on palpation. By ultrasonography, the corresponding distances were 3.5 cm (SD 1.05, SE 0.47) and 7.0 cm (SD 1.41, SE 0.63). Both methods showed a similar overlap length. However, ultrasonography revealed a shorter distance between the dorsal tubercle of the radius and the ulnar border of the first compartment than palpation (p = 0.0249).

CONCLUSIONS

Our findings indicate that a basic knowledge of anatomy should help health professionals diagnose forearm intersection syndrome through palpation and, if available, ultrasonography.

Co-occurrence of asymmetrical bilateral extensor carpi radialis intermedius and bilateral sternalis muscles in an anatomical donor

The presence of anatomical variants in the body may pose clinical challenges to inexperienced surgeons or clinicians and could cause misdiagnosis or treatment errors. Similarly, anatomical variations in cadavers pose educational dilemmas to students in gross anatomy dissection because of the inadequate coverage of anatomical variants in currently available resources, including textbooks. Students experience challenges in their learning experience, dissection process, and translation of clinically relevant information when presented with an anatomical variation. The authors report the rare finding of a bilateral sternalis muscle variant and asymmetrically bilateral extensor carpi radialis intermedius muscles in a single anatomical donor during dissection and the dilemma of students to find out what they were.

Extensor Carpi Radialis Longus Tenodesis Using a Biotenodesis Screw for Treatment of Symptomatic Geissler 2 Scapholunate Dissociation

Treatment of scapholunate dissociation (SLD) depends on the degree of injury. We present our technique of extensor carpi radialis longus (ECRL) tenodesis for Geissler grade 2 SLD and our preliminary results. After arthroscopic confirmation of Geissler grade 2 SLD, we use a single incision and a polyetheretherketone (PEEK) anchor, attaching half of the ECRL tendon to the scaphoid. Preliminary results include improvements in QDASH, QDASH (work) and QDASH (sports/music), a median satisfaction level of 4/5 (satisfied), and a low complication rate. Our method is a safe, reproducible, and effective treatment of symptomatic Geissler grade 2 SLD that has failed nonoperative management, with technical advantages over alternative methods in the literature.

Carpal Realignment Using a Strip of Extensor Carpi Radialis Longus Tendon

Scapholunate instability can lead to posttraumatic dysfunction of the wrist. If unrecognized, it commonly leads to degenerative osteoarthritis. Numerous reparative techniques have been proposed with mixed long-term success. We present a technique that uses a distally based strip of the extensor carpi radialis longus to better maintain reduction of the scaphoid and reconstruct the volar and dorsal scapholunate ligament and the scaphotrapezium-trapezoid ligament. To illustrate the technique, we describe a clinical case with 17 months of follow-up.

An anatomical study of additional radial wrist extensors including a unique extensor carpi radialis accessorius

BACKGROUND

In this study, 82 forearms from 41 cadavers were dissected to establish the incidence of variant additional radial wrist extensors. Three variants have been described in the literature: extensor carpi radialis intermedius (ECRI), extensor carpi radialis accessorius (ECRA) and extensor carpi radialis tertius (ECRT).

MATERIALS AND METHODS

Of the 41 cadavers studied, 5/41 (12%) had an additional radial wrist extensor. Of these 5 individuals, 2 had bilateral additional muscles and 3 were unilateral. Of the 82 forearms, 7/82 (9%) had additional radial wrist extensors.

RESULTS

We found 4 examples of ECRI and 3 examples of ECRA. We did not find any examples of ECRT. One specimen of ECRA had an atypical, previously undescribed, course.

CONCLUSIONS

These accessory muscles are of clinical relevance, as they may be a contributing factor in tennis elbow and nerve entrapment, or cause diagnostic confusion, especially in ultrasound scans. However, they may also be used for tendon transfer. Of the 7 muscles found in the current study, 3 would have been suitable for such procedures.

Ischemia Increases the Twitch Latent Period in the Soleus and Extensor Carpi Radialis Longus Muscles from Adult Rats

Complete ischemia and reperfusion effects on twitch force (∫(F·t)), twitch latent period (TLP), maximal rate of rise of twitch tension (δF/δt)_max, and twitch maximum relaxation rate (TMRR) were assessed. We divided 36 adult rats into four groups; two control groups (n = 9), a group undergoing 1 hour of ischemia followed by 1 hour of reperfusion (n = 9), and one group exposed to 2 hours of ischemia followed by 1 hour of reperfusion (n = 9). We have induced twitch contractions every 10 minutes in the soleus and the extensor carpi radialis longus (ECRL). Twitch contractions were recorded and then analyzed for ∫(F·t), TLP, (δF/δt)_max, and TMRR. During 1 hour and 40 minutes of ischemia, TLP increased to 179 ± 24% (p < 0.05) in the soleus and to 184 ± 16% (p < 0.05) in the ECRL, an effect that was partially recovered during 1 hour of reperfusion. This increase started after 20 minutes of ischemia in the soleus and after 40 minutes of ischemia in the ECRL. The increase was faster in the ECRL and peaked at the same time for both muscular groups. ∫(F·t) and (δF/δt)_max decreased during 1 hour of ischemia to 46 ± 7% (p < 0.05) in the soleus and to 40 ± 7% (p < 0.05) in the ECRL. TMRR decreased during 1 hour of ischemia to 39 ± 5% (p < 0.05) in the soleus and to 54 ± 8% (p < 0.05) in the ECRL. During 1 hour of reperfusion all of them recovered close to control values.

Anodal tDCS over SMA decreases the probability of withholding an anticipated action

Previous research has shown that the supplementary motor area (SMA) is critical in movement inhibition. Recently it was shown that applying transcranial direct current stimulation (tDCS) over SMA affected participants' ability to inhibit their movement in a stop-signal reaction time task (Hsu et al. [11]). Of interest in the current study was whether modulating SMA excitability using tDCS would have similar effects in an anticipation-timing stop-signal task. Participants performed 2 sessions each consisting of a pre- and post-tDCS block of 160 trials in which they were instructed to extend their wrist concurrently with the arrival of a pointer to a target (i.e., a clock hand reaching a set position). In 20% of trials (stop trials) the pointer stopped 80, 110, 140, 170, or 200 ms prior to the target, and on these trials participants were instructed to inhibit their movement if possible. Anodal and cathodal tDCS (separated by at least 48 h) was applied for each participant between the pre- and post-tDCS blocks. No change in the proportion of successfully inhibited movements on stop trials was found following cathodal tDCS (p>.05). However, anodal tDCS resulted in a decreased proportion of successfully inhibited movements on stop trials (p=002), and an earlier movement onset on control trials (p<.01). This suggests that the SMA may be more involved in initiation than in inhibition of anticipatory movements. Furthermore these data suggest that differences in initiation and inhibitory processes exist between stop-signal reaction time and anticipation-timing stop-signal tasks.

Burnei's technique in the treatment of radial head displacement; innovative surgery. Study on two cases

INTRODUCTION

Dislocation of the radial head, congenital or traumatic, anteriorly, posteriorly or laterally displaced, requires surgery to reseat and stabilize the head of the radius within the joint, in order to restore elbow flexion and, as much as possible, pronation-supination.

SCOPE

This article is meant to present the technique of proximal radial-ulnar ligament plasty using the extensor carpi radialis longus (ECRL) tendon, as well as other techniques for the stabilization of a dislocated radial head. The ECRL tendon technique, quadrate and annular ligament reconstruction variant was first used by Gh. Burnei in 1985, at Mangalia Municipal Hospital, Romania.

MATERIALS AND METHOD

This study contains two clinical cases, a 6-year-old girl with congenital dislocation of the radial head, and a 10-year-old boy with traumatic dislocation of the radial head, both of whom were treated by open reduction and stabilization of the dislocation with the ECRL tendon, using the Burnei procedure.

RESULTS

In both cases, the operation was successful in the reduction and stabilization of the dislocated radial head, whose position was maintained in flexion-extension and pronation-supination, and in the reconstruction of the annular ligament using Burnei's procedure, variant 2. Postoperatively, the clinical evolution was good, the patients having regained elbow mobility. The child with congenital dislocation exhibits normal flexion and pronation-supination within normal range, and the traumatic dislocation also exhibits normal flexion and pronation-supination limited with 20 degrees. Radiologically, in both cases the radial head is anatomically placed relatively to the humeral capitellum, in both flexion and extension.

DISCUSSION

Stabilization of the radial head in traumatic or congenital dislocation can only be surgically achieved. Congenital dislocation of the radial head requires the reconstruction of the proximal radial-ulnar joint, preferably at a young age, in order to avoid subsequent complications, culminating in ulnar or radial nerve paralysis. Traumatic dislocation of the radial head is usually accompanied by the fracture of the ulna, but may be encountered in isolation.

CONCLUSIONS

The Burnei procedure is an alternative for the treatment of radial head dislocation and is advantageous because of the use of a study, well vascularized tendon, which allows, when needed, the complete reconstruction of the proximal radial-ulnar ligaments, or just the annular ligament, in order to stabilize the head of the radius within the elbow joint. Also, the technique doesn't require osteotomies or an osteosynthesis requiring another surgery to remove the synthesis materials.

Anatomical variation of radial wrist extensor muscles: a study in cadavers

OBJECTIVE

The tendons of the extensor carpi radialis longus and brevis muscles are quite useful in tendon transfer, such as in correction of finger clawing and restoration of thumb opposition. Knowledge of additional radial wrist extensor muscle bellies with independent tendons is useful in the above-mentioned surgical procedures.

METHODS

The skin, subcutaneous tissue, and antebrachial fascia of 48 (24 on the right side and 24 on left side) male upper limb forearms were dissected. The following aspects were then analyzed: (a) the presence of additional muscle bellies of radial wrist extensors, (b) the origin and insertion of the additional muscle, and (c) measurements of the muscle bellies and their tendons.

RESULTS

Five out of 48 upper limbs (10.41%) had additional radial wrist extensors; this occurred in 3 out of 24 left upper limbs (12.5%) and 2 out of 24 right upper limbs (8.3%). In one of the right upper limbs, two additional muscles were found. The length and width of each additional muscle belly and its tendon ranged between 2 - 15 cm by 0.35 - 6.4 cm and 2.8 - 20.8 cm by 0.2 0.5 cm, respectively. The additional radial wrist extensor tendons in our study basically originated either from the extensor carpi radialis longus or brevis muscles and were inserted at the base of the 2nd or 3rd metacarpal bone.

CONCLUSION

The present study will inform surgeons about the different varieties of additional radial wrist extensors and the frequency of their occurrence.