Notes on the Accessory Flexor Carpi Ulnaris Muscle: A Rare Supernumerary Variation

Abstract

Variations of the forearm muscles are well described in the literature. In spite of that, reports regarding the accessory flexor carpi ulnaris muscle are scarce due to its rarity. This muscle usually originates from the medial epicondyle of the humerus with the flexor muscle mass and inserts itself into the palmar aponeurosis or the pisiform bone together with the flexor carpi ulnaris muscle. Supernumerary and anomalous muscles of the anterior compartment of the forearm have been associated with ulnar nerve and artery compression. Furthermore, they may also mimic neuromas and soft tissue tumors. The study of supernumerary muscles is necessary, as they may be an option to tendon grafts and muscle flaps. The aim of this paper is to describe the presence of the accessory flexor carpi ulnaris muscle on the left forearm of a cadaver fixated in a phenol solution and discuss its clinical and anthropological significance.

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

“…At about 5 weeks of gestation, the myoblasts originating from the myotomes migrate to specific sites in the upper limb bud to develop into the musculature of the upper limb. Myoblast cells aggregate into two muscle masses -the ventral and the dorsal muscle masses, which give rise to the flexor and the extensor group of muscles respectively (Pires et al, 2019). The skeletal muscle fibres may be identified in an embryo by approximately 7 weeks of intrauterine life.…”