Accessory coracobrachialis muscle with two bellies and abnormal insertion - case report

Abstract

<p><strong>Objective</strong>. In the current study a brief review is presented of the coracobrachialis muscle’s morphological variability, action, embryological development and clinical significance. <strong>Case report</strong>. We report a case of a left-sided coracobrachialis muscle consisting of two bellies. The deep belly inserts into the usual site in the middle area of the anteromedial aspect of the left humerus, whereas the superficial belly inserts through a muscular slip into the brachial fascia and the medial intermuscular septum, forming a musculo-aponeurotic tunnel in the middle region of the left arm, for the passage of the median nerve, brachial artery and veins, medial antebrachial cutaneous nerve and ulnar nerve. <strong>Conclusion</strong>. Awareness of such a muscle variant should be kept in mind by physicians and surgeons during interpretation of neural and vascular disorders of the upper limb, since such a variant may potentially lead to entrapment neuropathy and/or vascular compression, predisposing to neurovascular disorders, as well as during preparation of that muscle in cases of utilizing it as a graft in reconstruction of defects.</p>

Possible points of compression of the ulnar nerve: Tricks and traps that await clinicians from an anatomical point of view

“…Untreated snapping triceps syndrome can lead to severe fully‐symptomatic ulnar neuropathy (Jacobson et al, 2001; Paraskevas et al, 2016; Rioux‐Forker et al, 2018). In addition, a low‐lying insertion of the medial head of the triceps brachii and tendon insertion could predispose to UN entrapment, as noted by Beltran et al (2014).…”

“…Georgiev et al (2018) also report the presence of this aberrant muscle, but its origin was on the medial side of the body of the humerus, where it was fused with the distal part of the CBM. Paraskevas et al (2016) found a two‐bellied variant of the CBM; the deep head followed its usual course and terminated at the medial side of the body of humerus, but the superficial head ended at the MIMS and brachial fascia. The fibers of the CBM participated in creating a musculoaponeurotic tunnel containing the brachial vein and artery, the medial antebrachial cutaneous nerve, and both the median and ulnar nerves.…”