Abstract

Purpose: The coracobrachialis muscle shows considerable morphological variability, some forms of which may have important surgical and radiological implications. We describe a rare variant in which the coracobrachialis continues distally as an accessory muscle belly coracoulnaris crossing the neurovascular bundle and inserting into the olecranon process. Methods: The variation was identified during routine cadaveric dissection of an embalmed male cadaver aged approximately 70 years. Detailed anatomical dissection was performed to document the origin, course, insertion, and relationships of the variant muscle. Results: The coracobrachialis originated normally from the apex of the coracoid process but did not insert into the humeral shaft. Instead, it formed an elongated accessory belly that crossed superficial to the median nerve and brachial vessels, fused with the long head of the triceps brachii, and inserted into the olecranon process. An additional anomalous attachment to the tendon of latissimus dorsi was observed. Conclusion: This rare configuration represents persistence of embryonic muscle primordia and may predispose to neurovascular compression or complicate surgical and radiological procedures involving the arm and axilla. Awareness of such variants is essential for clinicians working in this region.

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