The anatomical variations of the cubital tunnel in a South African body donor sample.

PURPOSE: The ulnar nerve (UN) courses through the cubital tunnel, which is a potential site of entrapment. Anatomical variations of the cubital tunnel may contribute towards cubital tunnel syndrome (CuTS), however, these are not well described. The aim was to compare the range of variations and dimensions of the cubital tunnel and the UN between sexes and sides of the body. METHODS: Sixty elbows from 30 embalmed bodies (17 males and 13 females) were dissected. The prevalence of the cubital tunnel retinaculum (CuTR) or anconeus epitrochlearis (AE) forming the roof of the tunnel was determined. The length, width, thickness, and diameter of the cubital tunnel and its roof were measured. The diameter of the UN was measured. RESULTS: The AE was present in 5%, whereas the CuTR was present in the remaining 95% of elbows. The tunnel was 32.1 ± 4.8 mm long, 23.4 ± 14.2 mm wide, 0.18 ± (0.22-0.14) mm thick, and the median diameter was 7.9 ± (9.0-7.1) mm, while the median diameter of the UN was 1.6 ± (1.8-1.3) mm. The AE was thicker than the CuTR (p < 0.001) and the UN was larger in elbows with the AE present (p = 0.002). The tunnel was longer in males (p < 0.001) and wider on the right (p = 0.014). CONCLUSION: The roof of the cubital tunnel was more frequently composed of the CuTR. The cubital tunnel varied in size between sexes and sides. Future research should investigate the effect of the variations in patients with CuTS.

The prevalence of the anconeus epitrochlearis muscle in a Central European population.

BACKGROUND: An anconeus epitrochlearis muscle (AE) is a common anatomical variant in the upper extremity, located at the medial aspect of the elbow. Its anatomical position contributes to the roof of the cubital tunnel. While it plays a role in protecting the ulnar nerve, it may also pose a risk for ulnar nerve compression. This study aimed to determine the true prevalence of AE in a Central European population. MATERIALS AND METHODS: The presence of AE was evaluated in 115 cadaveric upper extremities from an undetermined number of subjects. The limbs for dissection were assumed to be healthy, and AE identification involved anatomical description and measurements. Data analysis aimed to determine the true prevalence, considering 95% confidence intervals. RESULTS: AE was present in 5 of the 115 cadaveric limbs (4.3%). Specimens lacking AE were observed, depicting normal cubital tunnel roof anatomy. When present, AE replaced the proximal part of the cubital tunnel roof, superficially coursing to the ulnar nerve. Morphological variations were noted. CONCLUSIONS: The true prevalence of AE was 4.3% (95% CI = 0.2%-8.4%), consistent with recent studies. Historical reports indicate varying true prevalence up to 26%, possibly linked to manual labor changes. Contrary to prior assumptions, our study did not find a significantly higher true prevalence in the European population. AE's association with cubital tunnel syndrome is complex, with both protective and potentially compressive roles.

Anconeus epitrochlearis muscle resulting in cubital nerve compressive neuropathy: Two case reports.

Background: The anconeus epitrochlearis muscle is an anatomical variant prevalent in amphibians but unusual in humans. In favorable cases, this muscle provides protection to the cubital nerve but can result in neuropathy due to compression of the cubital nerve. Case Description: We present two cases with different clinical manifestations but both did not respond to conservative treatment. We opted for a surgical decompression where the anconeus epitrochlearis muscle was found intraoperatively, and the muscle fibers were dissected. Conclusion: Considering the presence of the muscle variant is the key point to intraoperatively achieve a complete dissection of the muscle fibers of the anconeus epitrochlearis muscle variant and obtain the decompression of the cubital nerve with satisfactory postoperative results.

Anconeus epitrochlearis muscle (epitrochlearisanconeus muscle; Musculus epitrochleoanconeus) with cubital tunnel syndrome - a rare but relevant clinical entity.

BACKGROUND: Compression of the ulnar nerve at the elbow within the cubital tunnel is related to the anatomical structures and is generally believed to be caused by Osborne's ligament (also known as the cubital retinaculum). However, in rare cases an anatomical variation of the developmental peculiarity of a remaining anconeus epitrochlearis muscle may be responsible for the disease. METHODS: We present a series of five cases in which an anconeus epitrochlearis muscle was found as the cause of illness. RESULTS: All patients presented with typical symptoms of numbness and tingling in the hand and ulnar fingers, and recurring pain as well as weakness of the ulnar innervated muscles. With neurophysiologically confirmed diminished nerve conduction velocity and unsuccessful conservative treatment, surgical decompression revealed an anconeus epitrochlearis muscle as the reason of compression. Full symptom relief was achieved immediately after the procedure in all cases. CONCLUSIONS: This article strives to call attention to this entity when diagnosing ulnar nerve compression. Myectomy and medial epicondylectomy is the preferred treatment option in such cases.

Dynamic Compression of the Ulnar Nerve Associated With the Anconeus Epitrochlearis Muscle: Do We Really Know Everything?

Ulnar nerve compression associated with the anconeus epitrochlearis muscle (AE) is an uncommon cause of peripheral nerve compression at the elbow. It is often seen in young women with a hypertrophied or severely edematous muscle. Its causes are unclear. Numerous observed features, such as a hypertrophic AE, a palpable mass on the medial side of the elbow, and the dynamic nature of symptoms, have sparked controversy in the literature. Its clinical presentation is often insidious, and occasionally symptoms only occur in prolonged positions (dynamic compression). EMG tests are usually negative, and a correct diagnosis relies on imaging. We present the case of a 21-year-old student and clarinet player who presented with dynamic compression of the ulnar nerve at the elbow associated with AE. Much remains to be elucidated about the incidence, pathophysiology, and contributing factors of this peripheral form of cubital compression. It may be time to revisit this condition.

The prevalence of the anatomical variation in a Turkish population: supernumerary muscle-anconeus epitrochlearis.

INTRODUCTION: The anconeus epitrochlearis (AE) muscle is an accessory muscle located between the medial cortex of the olecranon and the inferior surface of the medial epicondyle, posterior to the ulnar nerve. This muscle may compress the ulnar nerve causing a clinical neuropathy. We aimed to determine the gender and side characteristics of the AE muscle in patients who underwent elbow magnetic resonance imaging (MRI) and report its prevalence in a Turkish population. MATERIALS AND METHODS: A total of 209 patients (210 elbows) who underwent elbow MRI between January and December 2020 were retrospectively evaluated. Cases with the AE muscle were included in the study. The craniocaudal (CC) dimension was examined from the coronal section, and the transverse (TR) and anteroposterior (AP) dimensions from the axial sections. Statistical analyses were performed to determine the relationship between the presence of the AE muscle and age, gender, and side (right/left). Differences between sexes and sides in terms of muscle sizes were evaluated using statistical tests. RESULTS: The AE muscle was detected in 17 patients (18 elbows) (8.1%). The mean age of the patients was 41.52 ± 14.63 years. There was no statistically significant difference between the male and female patients in terms of age. This accessory muscle was found in nine female (9.8%) and eight male (6.3%) patients in total. There was one (0.5%) patient with the bilateral AE muscle, who was female. The accessory muscle was located in the right elbow in 13 patients (10.71%), and left elbow in five (4.10%). It was more common in the right elbow in both genders. The muscle was larger in the male patients and the right elbow, but this was not statistically significant. CONCLUSION: The prevalence of the AE muscle was determined to be 8.1% in a Turkish population, and this muscle was more common among the women and in the right elbow.

Evolutionary adaptations in the flexor digitorum profundus muscle in Tamandua mexicana (Xenarthra, Myrmecophagidae).

The northern tamandua (Tamandua mexicana) is a neotropical mammal of the order Pilosa, suborder Vermilingua, and family Myrmecophagidae. This species has anatomical and functional adaptations in its forelimb for semiarboreal quadrupedal locomotion. Several studies have reported that the medial head of the triceps brachii and flexor digitorum profundus muscles are fused in species belonging to the family Myrmecophagidae. However, there is no reference to the innervation in these. The triceps brachii muscle is commonly innervated by the radial nerve and the flexor digitorum profundus muscle by the ulnar and median nerves. This study aims to describe the gross anatomy of the flexor digitorum profundus muscle in Tamandua mexicana with respect to the shape, origin, insertion, innervation, and arterial supply. Both forelimbs of nine specimens were used, which were dissected from superficial to deep layers. The formalin-fixed caudomedial forearm muscles were weighed, and the weight percentages of individual forearm muscle specimens were calculated. The flexor digitorum profundus had the highest weight among the forearm muscles and consisted of five heads (three humerals, one radial, and one ulnar). These heads were innervated by median and ulnar nerves; therefore, based on the innervation pattern, we concluded that the medial head of the triceps brachii muscle is not fused with the flexor digitorum profundus. Therefore, the flexor digitorum profundus muscle is highly developed in Tamandua and occupies the caudal part of the arm and forearm, which is an evolutionary adaptation that could have occurred during evolution from the common ancestor of Tamandua and Myrmecophaga.

Prevalence and Clinical Manifestations of the Anconeus Epitrochlearis and Cubital Tunnel Syndrome.

Background: The true prevalence of the anconeus epitrochlearis (AE) and the natural history of cubital tunnel syndrome associated with this anomalous muscle are unknown. The purpose of this study was to evaluate the prevalence of AE and to characterize the preoperative and postoperative features of cubital tunnel syndrome caused by compression from an AE. Methods: All elbow magnetic resonance imaging (MRI) scans and all patients undergoing cubital tunnel surgery during a 20-year period were identified and retrospectively reviewed for the presence of an AE. All patients with an AE identified intra-operatively were matched to patients with no AE identified at surgery based on age, sex, concomitant procedures, and year of surgery. Preoperative and postoperative physical exam findings, electrodiagnostic study results, time to improvement, and reoperations were compared between the groups. Results: A total of 199 patients had an elbow MRI, and 27 (13.6%) patients were noted to have an AE present. Average time to improvement after surgical release was 23.0 days for patients with an AE and 33.2 days for patients with no AE. Twenty-seven patients with an AE noted improvement at the first postoperative visit (68%) compared to 15 patients without an AE (33%). No patients with an AE underwent reoperation for recurrent symptoms (0%) compared with four patients (10%) without an AE. Conclusions: The prevalence of AE in our study is 13.6%. These patients experience quicker and more reliable symptom improvement after surgical release than those without the anomalous muscle.

Variant of the Anconeus Epitrochlearis Muscle: A Case Report.

The anconeus epitrochlearis is a muscle variant sometimes present at the elbow. It is present in up to 34% of individuals and has been implicated in some cases of cubital tunnel syndrome. We report an unusual variant of this muscle with additional proximal attachments in the arm. We will review and discuss the background and the clinical relevance of such a muscle.

Cubital Tunnel Syndrome Caused by Anconeus Epitrochlearis Muscle.

OBJECTIVE: We evaluated the clinical manifestation and surgical results following operative treatment of cubital tunnel syndrome (CuTS) caused by anconeus epitrochlearis (AE) muscle. METHODS: Among 142 patients who underwent surgery for CuTS from November 2007 to October 2015, 12 were assigned to the AE group based on discovery of AE muscle; 130 patients were assigned to the other group. We analyzed retrospectively; age, sex, dominant hand, symptom duration, and weakness in hand. Severity of the disease was evaluated using the Dellon classification and postoperative symptom were evaluated using disability of arm shoulder and hand (DASH) and visual analogue scale (VAS) scores. Surgery consisted of subfascial anterior transposition following excision of AE muscle. RESULTS: AE muscle was present in 8.5% of all patients, and was more common in patients who were younger and with involvement of their dominant hand; the duration of symptom was shorter in patients with AE muscle. All patients showed postoperative improvement in symptoms according to DASH and VAS scores. CONCLUSION: The possibility of CuTS caused by AE muscle should be considered when younger patients have rapidly aggravated and activity-related cubital tunnel symptoms with a palpable mass in the cubital tunnel area. Excision of AE muscle and anterior ulnar nerve transposition may be considered effective surgical treatment.

Quantitative magnetic resonance imaging analysis of the cross-sectional areas of the anconeus epitrochlearis muscle, cubital tunnel, and ulnar nerve with the elbow in extension in patients with and without ulnar neuropathy.

BACKGROUND: The purpose of this study was to assess the cross-sectional area of the anconeus epitrochlearis muscle (AEM), cubital tunnel, and ulnar nerve with the elbow in extension in patients with and without ulnar neuropathy. METHODS: We performed a retrospective, level IV review of elbow magnetic resonance imaging (MRI) studies. Elbow MRI studies of 32 patients with an AEM (26 men and 6 women, aged 18-60 years), 32 randomly selected patients without an AEM (aged 16-71 years), and 32 patients with clinical ulnar neuritis (22 men and 10 women, aged 24-76 years) were reviewed. We evaluated the ulnar nerve cross-sectional area proximal to, within, and distal to the cubital tunnel; AEM cross-sectional area; and cubital tunnel cross-sectional area. RESULTS: We found no significant difference in the nerve caliber between patients with and without an AEM. No correlation was found between the AEM cross-sectional area and ulnar nerve cross-sectional area within the cubital tunnel (r = 0.14). The mean cubital tunnel cross-sectional area was larger in patients with an AEM. Only 4 of the 32 patients with an AEM had findings of ulnar neuritis on MRI. Of the 32 patients with a clinical diagnosis of ulnar neuritis, only 2 had an AEM. CONCLUSIONS: With the elbow in extension, the presence or cross-sectional area of an AEM does not correlate with the area of the ulnar nerve or cubital tunnel. Only a small number of individuals with MRI evidence of an AEM had clinical evidence of ulnar neuropathy. Likewise, MRI evidence of an AEM was found in only a small number of individuals with clinical evidence of ulnar neuropathy.

Cubital Tunnel Syndrome Caused by Anconeus Epitrochlearis Muscle

OBJECTIVE: We evaluated the clinical manifestation and surgical results following operative treatment of cubital tunnel syndrome (CuTS) caused by anconeus epitrochlearis (AE) muscle. METHODS: Among 142 patients who underwent surgery for CuTS from November 2007 to October 2015, 12 were assigned to the AE group based on discovery of AE muscle; 130 patients were assigned to the other group. We analyzed retrospectively; age, sex, dominant hand, symptom duration, and weakness in hand. Severity of the disease was evaluated using the Dellon classification and postoperative symptom were evaluated using disability of arm shoulder and hand (DASH) and visual analogue scale (VAS) scores. Surgery consisted of subfascial anterior transposition following excision of AE muscle. RESULTS: AE muscle was present in 8.5% of all patients, and was more common in patients who were younger and with involvement of their dominant hand; the duration of symptom was shorter in patients with AE muscle. All patients showed postoperative improvement in symptoms according to DASH and VAS scores. CONCLUSION: The possibility of CuTS caused by AE muscle should be considered when younger patients have rapidly aggravated and activity-related cubital tunnel symptoms with a palpable mass in the cubital tunnel area. Excision of AE muscle and anterior ulnar nerve transposition may be considered effective surgical treatment.

Cubital Tunnel Syndrome Caused by Anconeus Epitrochlearis Muscle

OBJECTIVE: We evaluated the clinical manifestation and surgical results following operative treatment of cubital tunnel syndrome (CuTS) caused by anconeus epitrochlearis (AE) muscle.METHODS: Among 142 patients who underwent surgery for CuTS from November 2007 to October 2015, 12 were assigned to the AE group based on discovery of AE muscle; 130 patients were assigned to the other group. We analyzed retrospectively; age, sex, dominant hand, symptom duration, and weakness in hand. Severity of the disease was evaluated using the Dellon classification and postoperative symptom were evaluated using disability of arm shoulder and hand (DASH) and visual analogue scale (VAS) scores. Surgery consisted of subfascial anterior transposition following excision of AE muscle.RESULTS: AE muscle was present in 8.5% of all patients, and was more common in patients who were younger and with involvement of their dominant hand; the duration of symptom was shorter in patients with AE muscle. All patients showed postoperative improvement in symptoms according to DASH and VAS scores.CONCLUSION: The possibility of CuTS caused by AE muscle should be considered when younger patients have rapidly aggravated and activity-related cubital tunnel symptoms with a palpable mass in the cubital tunnel area. Excision of AE muscle and anterior ulnar nerve transposition may be considered effective surgical treatment.

Ultrasound Diagnosis of Double Crush Syndrome of the Ulnar Nerve by the Anconeus Epitrochlearis and a Ganglion.

Double compression of the ulnar nerve, including Guyon's canal syndrome associated with cubital tunnel syndrome caused by the anconeus epitrochlearis muscle, is a very rare condition. We present a case of double crush syndrome of the ulnar nerve at the wrist and elbow in a 55-year-old man, as well as a brief review of the literature. Although electrodiagnostic findings were consistent with an ulnar nerve lesion only at the elbow, ultrasonography revealed a ganglion compressing the ulnar nerve at the hypothenar area and the anconeus epitrochlearis muscle lying in the cubital tunnel. Careful physical examination and ultrasound assessment of the elbow and wrist confirmed the clinical diagnosis prior to surgery.

The anconeus epitrochlearis muscle may protect against the development of cubital tunnel syndrome: a preliminary study.

OBJECTIVE The authors hypothesized that when the anatomical variant of an anconeus epitrochlearis is present, the risk of developing cubital tunnel syndrome would be reduced by replacing the normal roof of the cubital tunnel (Osborne's ligament) with a more forgiving muscular structure, the anconeus epitrochlearis. The authors further hypothesized that when the presence of an anconeus epitrochlearis contributes to ulnar neuropathy, it would be secondary to muscular hypertrophy, thereby making it more likely to occur in the dominant arm. Therefore, the goal of the present study was to evaluate these hypotheses. METHODS This retrospective cohort study was performed by reviewing the records of all adult patients who underwent operative intervention for cubital tunnel syndrome between 2005 and 2014 as the experimental group and all asymptomatic patients in the medical literature who were part of a series reporting the prevalence of an anconeus epitrochlearis as the control group. The primary outcome of interest was the presence of an anconeus epitrochlearis in asymptomatic individuals versus patients with cubital tunnel syndrome. RESULTS During the study period, 168 patients underwent decompression of the ulnar nerve for cubital tunnel syndrome, and an anconeus epitrochlearis was found at surgery in 9 (5.4%) patients. The control group consisted of 634 asymptomatic patients from the medical literature, and an anconeus epitrochlearis was present in 98 (15.5%) of these patients. An anconeus epitrochlearis was present significantly less frequently in the symptomatic patients than in asymptomatic individuals (p < 0.001). Among patients undergoing surgical decompression, an anconeus epitrochlearis was associated with symptoms in the dominant arm (p = 0.037). CONCLUSIONS The authors found that an anconeus epitrochlearis was present significantly less often in patients with cubital tunnel syndrome than in asymptomatic controls. The mechanism of protection may be that this muscle decreases the rigidity of the entrance into the cubital tunnel. When an anconeus epitrochlearis does contribute to cubital tunnel syndrome, it is significantly more likely to occur in the dominant arm, possibly due to repetitive use and hypertrophy of the anconeus epitrochlearis. The presence of an anconeus epitrochlearis may be protective against the development of cubital tunnel syndrome, although this is a preliminary finding.

Ultrasound Diagnosis of Double Crush Syndrome of the Ulnar Nerve by the Anconeus Epitrochlearis and a Ganglion

Double compression of the ulnar nerve, including Guyon's canal syndrome associated with cubital tunnel syndrome caused by the anconeus epitrochlearis muscle, is a very rare condition. We present a case of double crush syndrome of the ulnar nerve at the wrist and elbow in a 55-year-old man, as well as a brief review of the literature. Although electrodiagnostic findings were consistent with an ulnar nerve lesion only at the elbow, ultrasonography revealed a ganglion compressing the ulnar nerve at the hypothenar area and the anconeus epitrochlearis muscle lying in the cubital tunnel. Careful physical examination and ultrasound assessment of the elbow and wrist confirmed the clinical diagnosis prior to surgery.

Comparison of Cubital Tunnel Syndrome with or without Anconeus Epitrochlearis: Are They Different?

PURPOSE: To assess the clinical difference between cubital tunnel syndrome with anconeus epitrochlearis (AE) and idiopathic cubital tunnel syndrome without known other causes. METHODS: This cross-sectional study included the 326 patients who were subjected to surgery because of cubital tunnel syndrome from 2008 to 2014. After exclusion of patients with other known causes of cubital tunnel syndrome, a total of 107 patients were divided into two groups; patients with and without AE. The clinical differences between two groups were analyzed retrospectively; age, sex, presence of intrinsic muscle atrophy, interval from symptom development to surgery, pinch power, the disabilities of the arm, shoulder and hand score and the nerve conduction velocity (NCV). RESULTS: Thirty four (10.4%) patients, being subjected to surgery had the AE. Among 107 patients who had no other known causes, 26 patients had AE. 19 out of 26 patients with AE was male. Average age of patients with AE was significantly younger. The interval from symptom development to surgery in AE patients was significantly shorter. Motor NCV of ulnar nerve at above elbow joint in comparison with that at below elbow joint in AE patient was more significantly decreased (14.3 m/sec vs. 8.3 m/sec). CONCLUSION: The AE in cubital tunnel syndrome is no more rare structure. In younger male patients with rapidly progressive worsening cubital tunnel symptoms, and if there is significant decrease of ulnar motor nerve velocity at above elbow in comparison with at below elbow, the AE should be considered as cause of ulnar neuropathy.

A rare cause of ulnar nerve entrapment at the elbow area illustrated by six cases: The anconeus epitrochlearis muscle.

Ulnar nerve entrapment is the second most common compressive neuropathy after carpal tunnel syndrome. The accessory anconeus epitrochlearis muscle - present in 4% to 34% of the general population - is a known, but rare cause of ulnar nerve entrapment at the elbow. The aim of this article was to expand our knowledge about this condition based on six cases that we encountered at our hospital between 2011 and 2015. Every patient had a typical clinical presentation: hypoesthesia or sensory deficit in the fourth and fifth fingers; potential intrinsics atrophy of the fourth intermetacarpal space; loss of strength and difficulty with fifth finger abduction. Although it can be useful to have the patient undergo ultrasonography or MRI to aid in the diagnosis, only electromyography (EMG) was performed in our patients. EMG revealed clear compression in the ulnar groove, with conduction block and a large drop in nerve conduction velocity. Treatment typically consists of conservative treatment first (splint, analgesics). Surgical treatment should be considered when conservative treatment has failed or the patient presents severe neurological deficits. In all of our patients, the ulnar nerve was surgically released but not transposed. Five of the six patients had completely recovered after 0.5 to 4years follow-up. Ulnar nerve entrapment at the elbow by the anconeus epitrochlearis muscle is not common, but it must not be ignored. Only ultrasonography, MRI or, preferably, surgical exploration can establish the diagnosis. EMG findings such as reduced motor nerve conduction velocity in a short segment of the ulnar nerve provides evidence of anconeus epitrochlearis-induced neuropathy.

[Two anomalous muscles of a forearm revealed by ulnar nerve compressions, a Double Crush syndrome]. / Malformation musculaire associée à une variation anatomique de l'avant-bras révélées par des compressions étagées du nerf ulnaire (Double Crush syndrome).

This article describes the concomitant presence of two anomalous muscles on a left forearm in a 40-year-old man. The anconeus epitrochlearis muscle was responsible for a cubital tunnel syndrome and the unusual origin of the flexor digiti minimi brevis muscle was responsible for a compartment syndrome with ulnar nerve compression at the level of Guyon's canal during effort diagnosed by MRI. Resection of these muscles relieved the symptoms and allowed the patient to return to work.

Cubital Tunnel Syndrome by Anconeus Epitrochlearis in an Adolescent / 대한정형외과학회잡지

Compression neuropathy of the ulnar nerve due to anconeus epitrochlearis muscle is rare in adolescents. It is usually known that the hypertrophied muscle in adult or weightlifting athletes compresses the ulnar nerve. There were only few case reports in children and adolescent relevant to athletic activities. In this case, a non-athlete 15-year-old girl developed compression ulnar nerve neuropathy caused by an anconeus epitrochearis muscle. This case is remarkable as an anconeus epitrochearis muscle is uncommon in non-athlete children and adolescent since a literature review revealed no previous report.