Identification of Aberrant Muscle Bellies in the Carpal Tunnel Using Sonography

Musculoskeletal sonography is being widely used for evaluation of structures within the carpal tunnel. While some anatomical variants, such as bifurcated median nerves and persistent median arteries, have been well documented, limited literature describes the sonographic appearance of aberrant muscle bellies within the carpal tunnel. Multiple examples of the sonographic appearance of flexor digitorum superficialis and lumbrical muscle bellies extending into the carpal tunnel are provided. Techniques for static image acquisition and analysis are discussed, and the use of dynamic imaging to confirm which specific muscle belly is involved is described. Knowledge of the potential presence of muscle bellies in these images and ability to identify these structures is vital to avoid misclassification or misdiagnosis as abnormal pathology. The case examples are situated among current published evidence regarding how such anomalies may be related to the development of pathologies, such as carpal tunnel syndrome.

Upper limb congenital muscular hypertrophy and aberrant muscle syndrome in children

Congenital muscle hypertrophy of the upper limb is a very rare condition with unknown aetiology. This descriptive observational and retrospective series included eight children followed by a multidisciplinary team from 2005 to 2017. The diagnosis was based on a cluster of clinical and radiological characteristics after elimination of differential diagnoses. Patients were categorized according to: anomalies of the wrist, anomalies of long fingers of intrinsic or extrinsic origin; and anomalies of the thumb with or without first web space contracture. Treatment begins in young children with hand orthoses to limit muscle contraction and joint malposition. The purpose of surgical treatment was to release contractures and to restore muscle balance through, in the main, finger intrinsic releases and first web releases. At the 2-year follow-up, we found that limited surgical procedures improved finger, thumb and wrist positions. We conclude that muscle hypertrophy is the main cause of deformity and that selective releases of contracted musculo-tendinous units and skin lengthening are effective. Level of evidence: IV

Carpal Tunnel Syndrome in Aberrant Muscle Syndrome: A Case Report and Review of the Literature

Aberrant Muscle Syndrome (AMS) is a rare congenital hand difference that is characterised by unilateral non-progressive muscular hyperplasia. The aetiology of aberrant muscle syndrome is not known, but a recently published case has shown a somatic PIK3CA activating mutation in a patient with AMS. Carpal tunnel syndrome (CTS) in children is rare. The most common causes are the mucopolysaccaridoses but space-occupying lesions have also been reported to cause CTS in children. We report the first case of CTS in a child with AMS successfully treated with open carpal tunnel release and excision of aberrant muscles.

An Aberrant Subclavius Posticus Muscle: A Case Report

Objective: An aberrant subclavius posticus muscle was found during routine dissection of the left infraclavicular fossa of a 60-year-old male cadaver. Presentation: This aberrant muscle arises antero-medially, from the costoclavicular ligament, runs postero-laterally, over the trunks of the brachial plexus, and postero-lateral has a common insertion with the omohyoid muscle. Conclusion: The presence of such an aberrant muscle may cause a dynamic compression of the subclavian artery and brachial plexus.

Bulky accessory brachialis muscle with abnormal aponeurosis: A case report

The brachialis muscle is one of the chief flexors of the upper arm, and its variation can affect the movements of the elbow joint. This case report presents a rare case of a large accessory brachialis muscle in the right arm that comes with an abnormal aponeurosis. The aponeurosis from the distal part of the aberrant muscle arches over the radial artery and is attached to the deep fascia of the right forearm. While rare, the presence of an accessory brachialis muscle coupled with the unusual aponeurosis can lead to compression of the radial artery, causing radial artery entrapment syndrome and creating potential difficulties in the catheterisation of the radial artery.

Bilateral Chondroepitrochlearis Muscle: Case Report, Phylogenetic Analysis, and Clinical Significance

Anomalous muscular variants of pectoralis major have been reported on several occasions in the medical literature. Among them, chondroepitrochlearis is one of the rarest. Therefore, this study aims to provide a comprehensive description of its anatomy and subsequent clinical significance, along with its phylogenetic importance in pectoral muscle evolution with regard to primate posture. The authors suggest a more appropriate name to better reflect its proximal attachment to the costochondral junction and distal attachment to the epicondyle of humerus, as “chondroepicondylaris”; in addition, we suggest a new theory of phylogenetic significance to explain the twisting of pectoralis major tendon in primates that may have occurred with their adoption to bipedalism and arboreal lifestyle. Finally, the clinical significance of this aberrant muscle is elaborated as a cause of potential neurovascular entrapment and as a possible hurdle during axillary surgeries (i.e., mastectomy).