Innervation of the anconeus epitrochlearis muscle: MRI and cadaveric studies

Abstract

Ulnar neuropathy at the cubital tunnel is common. However, a rare form of ulnar neuropathy here is due to compression from an accessory muscle, the anconeus epitrochlearis. Reports in the literature regarding the details of this muscle's innervation are vague, so the aim of the present study was to characterize this anatomy more clearly. This was a combined review of magnetic resonance imaging (MRI) from patients with an anconeus epitrochlearis and ulnar neuropathy and cadaveric dissections to characterize the innervation of this variant muscle. A review of 11 patients and three reports of ulnar neuropathy and an anconeus epitrochlearis in the literature revealed no MRI changes consistent with acute denervation of this muscle. However, in two cases, there were signs of chronic denervation of the muscle. Dissection of five cadavers revealed that the nerve supply to the anconeus epitrochlearis originated proximal to the medial epicondyle, traveled parallel to the ulnar nerve, terminated on the deep aspect of this muscle, and had a mean length of 60 mm. This clinicoanatomical study provides evidence that the innervation of the anconeus epitrochlearis is proximal to the muscle and on its deep aspect. Clin. Anat. 32:218-223, 2019.

Prevalence of the anconeus epitrochlearis muscle in a Turkish population and its general characteristics on magnetic resonance imaging

“…[20] detected bilateral accessory muscles in a single cadaver, but these studies did not provide any information on the gender of cases. The AE muscle was reported in one female (8%) patient among the 13 cases evaluated by Kim et al [10], one female cadaver among 40 cadavers in a study by Grewal et al [4], and two of the ve patients (one male and one female) with cubital tunnel syndrome evaluated by Ruiter et al [16]. In our study, the only case with the bilateral AE muscle was female (0.5%).…”

“…[13] found the mean length of the muscle to be 18 ± 5 mm and its volume to be 883 ± 295 mm 3 . In another study including 11 patients with the AE muscle, Grewal et al [4 ] determined the mean muscle thickness as 7 (range, 2-13) mm, length as 22 (range, 15-32) mm, and width as 12 (range, 4-15) mm. In the current study, the mean length, width, and thickness of the AE muscle were 17.41 ± 4.6 mm, 10.64 ± 3.42 mm, and 4.76 ± 1.15 mm, respectively, and these measurements were consistent with the literature.…”

“…There are few studies in the literature reporting on the AE muscle dimensions [4,13]. Nascimento et al…”

“…In publications in the literature evaluating European populations, the AE muscle is reported more frequently in men[3,4,10,12, 13, 15]. The prevalence of this muscle in men was reported to be 65.5% by Nascimento et al[13] and 55.5% by Wilson et al[15].…”

Medial elbow anatomy: A paradigm shift for UCL injury prevention and management

“…Previous anatomical studies have reported that the ulnar nerve traversed the upper arm from the anterior to the posterior compartment at the arcade of Struthers to enter the cubital tunnel, the floor of which consisted of the olecranon, medial joint capsule, posterior bundle of the UCL, and the transverse ligament (e.g., Cooper's ligament) (Morrey and An, ; Granger et al, ). Previous reports have also described that the compression of the ulnar nerve may occur at several sites along this path, such as Osborne's ligament (Bozentka, ; Granger et al, ), the brachial ligament (Wehrli and Oberlin, ), the anconeus epitrochlearis (Grewal et al, ), and the subanconeus muscle, of which the highest concentration of fibers was in the joint capsule near the groove of the ulnar nerve (Tubbs et al, ). In the current study, we identified the TS between the FDS and FCU, in addition to the TS between the PT and FDS muscles.…”