Does the articularis cubiti muscle really exist? Anatomical, histological, and magnetic resonance imaging study with a narrative review of literature.

Although the term articularis cubiti muscle is incorporated in the official anatomical nomenclature, only sparse data about its appearance are available. It is usually described as few fibres originating from the medial head of the triceps brachii muscle and inserting to the capsule of the elbow joint. However, the most recent observations regarding the morphological relations in the posterior elbow region point towards the absence of a well-defined muscle. Therefore, this study was designed to verify the existence of the articularis cubiti muscle in question and to compile more data on the topographical features of the subtricipital area near the posterior aspect of the elbow. To address these questions, 20 embalmed upper limbs were dissected, and seven samples were collected for histological analysis. The laboratory findings were then correlated with 20 magnetic resonance imaging (MRI) scans of the elbow. Consequently, a narrative review of literature was performed to gain more information on the discussed muscle in a historical context. Upon the anatomical dissection, muscular fibres running from the posterior aspect of the shaft of the humerus to the elbow joint capsule and olecranon were identified in 100% of cases. Histologically, the connection with the joint capsule was provided via winding bands of connective tissue. On MRIs, the muscular fibres resembled a well-demarcated thin muscle located underneath the medial head of the triceps brachii muscle. Combined with the review of literature, we concluded that the constant articularis cubiti muscle originates from the posterior shaft of the humerus and attaches indirectly to the posterior aspect of the elbow joint capsule and directly to the superior portion of the olecranon. The obtained results slightly differ from the modern description, but are in agreement with the original publication, which has become misinterpreted throughout time. Presumably, the misused description has led to questioning the existence of an independent muscle. Moreover, our findings attribute to the articularis cubiti muscle, a function in pulling on the posterior aspect of the elbow joint capsule to prevent its entrapment, and possibly also a minor role in extension of the forearm. The presented results should be taken into consideration when intervening with the posterior aspect of the elbow joint because the articularis cubiti muscle poses a consistently appearing landmark.

Anconeus-sparing minimally invasive approach for lateral ulnar collateral ligament reconstruction using a triceps tendon autograft is an effective and safe treatment for chronic posterolateral instability of the elbow.

BACKGROUND: Surgical treatment helps to restore stability of the elbow in patients with posterolateral rotatory instability (PLRI). The anconeus muscle is one of the most important active stabilizers against PLRI. A minimally invasive anconeus-sparing approach for lateral ulnar collateral ligament (LUCL) reconstruction using a triceps tendon autograft has been previously described. The purpose of this study was to evaluate the outcome of this intervention and identify risk factors that influenced the clinical and patient-reported outcomes. METHODS: Sixty-one patients with chronic PLRI and no previous elbow surgery who underwent surgical reconstruction of the LUCL using a triceps tendon autograft in a minimally invasive anconeus-sparing approach during 2012 and 2018 were evaluated. Outcome measures included a clinical examination and the Oxford Elbow Score (OES) and the Mayo Elbow Performance Score (MEPS) questionnaires. Subjective patient outcomes were evaluated with the visual analog scale (VAS) for pain and the Subjective Elbow Value (SEV). Integrity of the common extensor tendons and centering of the radial head were assessed preoperatively on standardized magnetic resonance images (MRIs). RESULTS: Fifty-two patients were available at final follow-up. The mean age of patients was 51 ± 12 years with a mean follow-up of 53 ± 14 months (range 20-76). Clinical examination after surgery (n = 41) showed no clinical signs of instability in 98% of the patients (P < .001) and a nonsignificant improvement in range of motion. OES, MEPS, and VAS scores averaged 40 ± 10 of 48 points, 92 ± 12 of 100 points, and 1 ± 2 points, respectively, all corresponding with good or excellent outcomes. The SEV was 88%, indicating very high satisfaction with the surgery. Only 1 patient had revision surgery due to pain, and there were no reported postoperative complications in this cohort. A radial head subluxation in the MRI correlated significantly with worse postoperative outcomes. CONCLUSIONS: The anconeus-sparing minimally invasive technique for posterolateral stabilization of the elbow using a triceps tendon autograft is an effective and safe treatment for chronic posterolateral instability of the elbow with substantial improvements in elbow function and pain relief with a very low rate of persistent clinical instability.

Anconeus syndrome: A potential cause for lateral elbow pain and its therapeutic management-A case report.

STUDY DESIGN: This is a case report. INTRODUCTION: Anconeus is a small, triangular muscle in the posterior aspect of the elbow, and it functions as weak elbow extensor and abducts the ulna during pronation. The contribution of anconeus muscle can cause lateral elbow pain, which is difficult to diagnose and treat. It also does not respond to the regular treatment for lateral epicondylitis. PURPOSE OF THE STUDY: The purpose of this study was to report anconeus muscle irritation as a sole cause for lateral elbow pain. METHODS: The patient was given an elbow splint for 4-6 weeks followed with eccentric and concentric strengthening to the elbow and wrist. RESULT: At the end of week 9, the patient was pain-free. CONCLUSION: The clients who are not responding with the usual treatment of lateral epicondylitis should be considered for any anconeus involvement.

The anconeus muscle revisited: double innervation pattern and its clinical implications.

PURPOSE: The aim of the present study is to describe in detail the morphology and innervation pattern of the anconeus muscle, bearing in mind clinical implications such as iatrogenic injuries during surgical elbow approaches. METHODS: A cadaveric study was performed; 56 elbows from 28 formalin-fixed cadavers belonging to the Anatomy Department of Universidad Complutense of Madrid were dissected. The triceps-anconeus nerve was located and dissected. A second innervation to the anconeus muscle from a branch of the posterior interosseous nerve (PIN) was occasionally detected. Taking the lateral epicondyle as a landmark, the entry points of both nerves in the muscle were referenced, the triceps-anconeus nerve was referenced at 0°, 30°, 45°, 70° and 90° of elbow flexion, and the PIN branch at 0°. RESULTS: Anconeus muscle was present in all specimens. The triceps-anconeus nerve was present in all of the dissected elbows. A branch from PIN to the anconeus muscle was present in 38 of the 54 elbows (70.4%). There were statistically significant differences in all measurements regarding the specimens' gender, being higher for men. CONCLUSIONS: There is evidence of a high frequency of a double innervation pattern for the anconeus muscle: the main branch of triceps-anconeus muscle depending on the radial nerve, which is liable to being damaged during posterior elbow approaches, and a secondary branch depending on the PIN. There are very few references to this finding in Anatomical literature and none with such a large sample size.

Radial Nerve F-wave reference values with surface electrodes from the anconeus muscle.

INTRODUCTION: We sought to obtain normative values for radial nerve F-wave variables, recording with surface electrodes from the anconeus muscle. METHODS: We tested 30 healthy participants (17 women, 13 men) and measured the following variables: number of F waves/40 traces (F%); minimum, maximum, and mean F-wave latency (FMIN, FMAX, FMED, respectively); F-wave chronodispersion (FCHR); interside differences of F% and FMIN (DF% and DFMIN, respectively). RESULTS: The mean F% was 41.3%; the normative values of FMIN, FMED, FMAX, and FCHR were < 21.2, <22.1, <23.3, and < 4.0 ms, respectively; and normative values of DF% and DFMIN were < 16.6% and < 1.1 ms, respectively. Height was the sole independent predictor in a regression model of FMIN, FMED, and FMAX; this explained 37%-44% of the variability. DISCUSSION: We identified a feasible and useful technique to record radial nerve F waves from the anconeus muscle and obtained normative values of F-wave variables. Muscle Nerve 59:244-246, 2019.

Anatomy and functional architecture of the anconeus muscle / Anatomía y arquitectura funcional del músculo ancóneo

The anconeus is a small muscle situated at the elbow. Although the anconeus is active during elbow extension its importance for the movement is probably small. It could work as an elbow stabilizer. The object of this study was to investigate some anatomic and architectural characteristics of the anconeus, in the hope of shedding light on its function. We studied twenty adult cadaveric specimens. The anconeus originates by the lateral epicondyle of the humerus and inserts along the proximal ulna. The superficial shape of the anconeus is triangular. Tridimensionally the anconeus resembles a hemisected rectangular-based pyramid, with the base at the ulna and apex at the lateral epicondyle. The muscle fibers arise obliquely from the tendinous expansion and inserts at the ulna. Thus, the architecture of the anconeus is penniform, an architecture able to produce more force then displacement. The design index of 0.3 also suggests a force muscle.

El ancóneo es un pequeño músculo situado en la región del codo. Aunque el músculo ancóneo es activo durante la extensión del codo su importancia para este movimiento es probablemente pequeña. Podría actuar como estabilizador del codo. El objetivo de este trabajo fue investigar algunas características anatómicas y arquitectónicas del músculo ancóneo, con la esperanza de lanzar una cierta luz en su función. Estudiamos 20 cadáveres de adultos. El músculo ancóneo se origina al lado del epicóndilo lateral y se inserta en la ulna. La forma superficial del músculo ancóneo es triangular. Tridimensionalmente, el músculo ancóneo se asemeja a la mitad de una pirámide de base rectangular, con la base en la ulna y el ápice lateral al epicóndilo lateral. Sus fibras musculares describen un trayecto oblicuo con una extensión tendinosa que se insertan en la ulna. Por lo tanto, la arquitectura del músculo ancóneo es peniforme, una arquitectura conveniente para producir mayor fuerza con el desplazamiento. El índice de diseño de 0,3 también lo sugiere como un músculo de fuerza.

Diagnostic Sensitivity of Several Muscles in Repetitive Nerve Stimulation Test for Myasthenia Gravis / 영남의대학술지

BACKGROUND: This study was undertaken to evaluate the diagnostic sensitivity of several muscles in repetitive nerve stimulation test (RNST) for myasthenia gravis (MG) patients. MATERIALS AND METHODS: The study population consisted of 39 MG patients classified by modified Ossermann's classification. Using Stalberg's method, RNST was systematically performed in facial (orbicularis oculi and nasalis) and upper extremity (flexor carpi ulnaris, abductor digiti quinti and anconeus) muscles. RESULTS: The significant electrodecremental response of RNST were noted in orbicularis oculi (58.9%), nasalis (51.3%), flexor carpi ulnaris (42%), anconeus (41%) and abductor digiti quinti muscles (27%). Among the 3 muscles of upper extremity (abductor digiti quinti, flexor carpi ulnaris and anconeus), the positive electrodecremental response of anconeus muscles was significantly higher than other two muscles (p<0.05) in type IIa, IIb and there were no statistical differences of the positive electrodecremental response between orbicularis oculi and nasalis muscles. The facial muscles showed more prominent decremental responses than upper extremity muscles in type I MG(p<0.05). In type IIa MG patients, there were no significant statistical differences between facial and upper extremity muscles but significant statistical differences among upper extremity muscles. In type IIb MG patients, there were no significant statistical differences in all tested muscles in spite of the increased positive electrodecremental response of RNST. CONCLUSION: On the basis of this study, RNST would be initially performed for the orbicularis or nasalis in type I MG and for the anconeus in type IIa or IIb MG.