Anomalies of the flexor carpi ulnaris: clinical case report and cadaveric study

Accessory Flexor Carpi Ulnaris Muscle in Humans: A Rare Anatomical Case with Clinical Considerations

Anatomical variations of the forearm flexor muscles are occasionally encountered. Though usually observed incidentally during autopsies or imaging studies, they may at times cause concern due to associated clinical symptoms. This report presents a case of unilateral accessory flexor carpi ulnaris (AFCU) muscle observed in a human male cadaver aged 78 years. During routine cadaveric dissection, an anomalous AFCU muscle was observed in the left forearm of a human male cadaver aged 78 years. Standard institutional guidelines pertaining to the use of human cadaver for teaching and research were followed. A thorough literature review about the flexor carpi ulnaris (FCU) through the PubMed, Embase and Google scholar databases was undertaken, using the keywords - accessory flexor carpi ulnaris muscle, aberrant flexor carpi ulnaris muscle and anatomical variation of flexor carpi ulnaris muscle. Relevant gross anatomical findings were recorded and photographed. AFCU was identified on the medial aspect of the distal third of the left forearm. The AFCU was found originating from the ante-brachial fascia and the fascia covering the FCU on the left forearm, forming a small separate belly deep to the main muscle. It terminated as a thin tendon running alongside the hypothenar muscles and attached distally to the base of the proximal phalanx of the little finger. The AFCU was found to be innervated by a branch of the ulnar nerve. Awareness about the rare AFCU muscle is clinically important as a possible cause of ulnar nerve compression but also as a possible graft in reconstruction surgeries.

Anatomical variations of the flexor carpi ulnaris in the fetal period

Introduction: The Flexor Carpi Ulnaris (FCU) is a part of the palmar the forearm muscle group and one of the most important muscles for upper limb functioning - is responsible for flexion and adduc­tion of the hand at the radio-carpal joint. There are clinically significant but rare anatomical variations of FCU. The variability of the FCU has not been described up to now, and no typology of the muscle based on its more variable terminal attachment has been created. Aim of the study: Determination of FCU muscle typology based on available fetal material. Material and methods: A total of 114 human fetuses (53 female, 61 male) between 117 and 197 days of fetal life were eligible for the study. Preparations were carried out using classical anatomical techniques based on a previously published procedure. Thanks to that significant anthropometric landmarks were vis­ible for the gathering of metric measurements. Metric measurements were taken and statistically analysed using R-Project software. Results: A new typology was created based on variable muscle insertions. Additionally, the presence of an atypically located, additional, separated muscle belly was described. A comparison of measurements of the left upper limb in relation to the right upper limb showed significant differences for forearm length to the anthropometric point of the stylion radiale, limb length, total FCU length and FCU length which means that the left limb is longer than the right limb. A comparison of FCU insertion types between left and right upper limb showed there’s no significant difference between counts of each type. Conclusion: The FCU is a muscle that is easy to palpate and may therefore act as a topographical marker for healthcare professionals. Knowledge of its variability is not only of theoretical importance but also has clinical sig­nificance. The current publication demonstrates presence of variability in FCU terminal attachment. Certainly, this topic requires further research and continued work on a detailed understanding of forearm anatomy in the fetal period.

Accessory flexor carpi ulnaris: case report and review of the literature

Most of the accessory muscles of the forearm described in the radiology literature are located either in the radial aspect of the forearm or towards the hypothenar eminence. We present an unusual case of an ulnar-sided distal forearm accessory flexor carpi ulnaris muscle presenting as a “pseudotumour“ demonstrated with both ultrasound and MRI, rarely reported in the current surgical and anatomical literature. Given the location and relation to the ulnar nerve towards Guyon’s canal, the accessory muscle may also predispose to distal ulnar nerve entrapment.

Ultrasound of the ulnar-palmar region of the wrist: normal anatomy and anatomic variations

Ultrasound (US) assessment of the wrist is frequently used for the evaluation of carpal tunnel due to high frequency of local compression of the median nerve (MN), but the ulnar-palmar wrist region (UPWR) has received limited attention in the medical literature. The possibilities of US in the assessment of UPWR are therefore likely underestimated by sonologists. This review article is focused on the US assessment of the normal anatomy and anatomic variations of the UPWR. The anatomy of this region of the wrist is complex and less studied than the radial side. In an effort to simplify it and to present it didactically, we have divided this region in three parts on the basis of osseous landmarks. Our review indicates sonography is effective in identifying the UPWR and related disorders, and is thus a valuable tool for ensuring appropriate management of a variety of disorders.

Clinical Application of Anomalous Muscles for Tendon Transfer in the Upper Limb: A Systematic Review of the Literature

Numerous anomalous muscles of the forearm and hand have been reported in the literature. The majority were encountered in cadaver dissections and some were incidentally detected during tendon transfer surgery. Because of the limited number of motors available for transfer, it may be advantageous if an anomalous muscle with favorable anatomy can function as a potential donor in a suitable clinical environment. Although several authors have illustrated various anomalies and their functional significance, the reports of actual utilization of such muscles as donors for tendon reconstructions are sparse. The aim of the study is to conduct a systematic review of the clinical applications of anomalous muscles in the upper extremity. After a thorough search of PubMed, Web of Science, Scopus, and Cochrane Library databases, only three out of 106 studies were found to be relevant. Two of them discussed the anomalous radial wrist extensor tendon transfer for thumb flexion. The third study described the usage of anomalous flexor carpi ulnaris (FCU) for thumb opposition and index finger flexion, and also proposed a classification. This is the first systematic review of the clinical application of anomalous muscles as donors in the upper extremity tendon transfer surgical procedures. Knowledge of the above classification helps in intraoperative evaluation of the type of the anomaly and the possible consideration of anomalous muscle as a source of transplant material in an appropriate clinical setting.

Accessory flexor carpi ulnaris muscle with associated anterior interosseous artery variation: case report with the definition of a new type and review of concomitant variants

PURPOSE

Knowledge of accessory flexor carpi ulnaris (AFCU) is not only important for proper orientation in the surgical field but it can be used for tendon transfer as well. AFCU commonly occurs with concomitant variants, and its presence should rise caution in order to prevent iatrogenic injury.

METHODS

During a routine dissection for research data collection at the Institute of Anatomy, a AFCU with concomitant variants was observed in a European cadaver fixed with Thiel's method. A thorough review of the literature concerning all the encountered variants was performed.

RESULTS

AFCU was found in the right upper limb with its insertion on the flexor retinaculum. Palmaris longus muscle was absent in this limb, and an accessory branch of the anterior interosseous artery coursed over the pronator quadratus muscle to anastomose with the ulnar artery 5 cm proximally to the pisiform. On the left hand, a variable lumbrical of the second finger originating from the flexor retinaculum was found, which was not described in the literature before.

CONCLUSIONS

AFCU commonly occurs together with concomitant variants, and special attention is needed when performing surgery on such forearm.

Supernumerary flexor carpi ulnaris--case report and review

Anomalies of Flexor carpi ulnaris (FCU) are uncommon and predominantly consist of abnormal insertion or extra tendinous bands. The presence of two separate bellies of FCU muscle with separate tendons has been termed as Digastric FCU. It is a very rare anomaly with only six previously reported cases and no report of clinical use of such anomalous muscle. We describe a case of anomalous FCU found incidentally in a patient operated for complex Post Volkmann's ischemic contracture deficits. On table each head of FCU was found to form separate belly and tendon. One tendon was used for the thumb opposition while the other for index finger flexion. Postoperatively, the patient had independent movement of thumb and index finger. This is the first reported case of clinical application of digastric FCU. We reviewed the literature for supernumerary FCU in general and digastric FCU in particular. We propose a new classification for supernumerary FCUs based on the clinical appearance and the probable embryological basis of the anomaly: Type 1 (Split tendons)--single muscle with two tendons; Type 2 (Digastric FCU)--for each head of FCU forming separate muscle bellies and tendons; and Type 3 (Accessory FCU)--abnormal muscle adjacent to normal FCU with combined features of FCU and Palmaris longus.

Accessory muscle in the forearm: a clinical and embryological approach

Muscular variations of the flexor compartment of forearm are usual and can result in multiple clinical conditions limiting the functions of forearm and hand. The variations of the muscles, especially accessory muscles may simulate soft tissue tumors and can result in nerve compressions. During a routine dissection of the anterior region of the forearm and hand, an unusual muscle was observed on the left side of a 65-year-old male cadaver. The anomalous muscle belly arose from the medial epicondyle approxiamately 1 cm posterolateral to origin of normal flexor carpi ulnaris muscle (FCU), and from proximal part of the flexor digitorum superficialis muscle. It inserted to the triquetral, hamate bones and flexor retinaculum. Passive traction on the tendon of accessory muscle resulted in flexion of radiocarpal junction. The FCU which had one head, inserted to the pisiform bone hook of hamate and palmar aponeurosis. Its contiguous muscles displayed normal morphology. Knowledge of the existence of muscle anomalies as well as the location of compression is useful in determining the pathology and appropriate treatment for compressive neuropathies. In this study, a rare accessory muscle has been described.