ANATOMIC VARIATION A rare accessory coracobrachialis muscle: a review of the literature Received: 5 March 2001 / Accepted: 29 July 2002 / Published online: 4 February 2003 Ó Springer-Verlag 2003 Abstract During previous dissections to investigate the incidence of the third head of the biceps brachii in ne- onate cadavers an accessory coracobrachialis muscle was unilaterally found in a neonate male cadaver. This muscle originated from the coracoid process and the capsule of the shoulder joint. It was inserted into the antebrachial fascia and the medial epicondyle of the humerus. The coracobrachialis muscle is used as a transposition flap in deformities of infraclavicular and axillary areas and in postmastectomy reconstruction. It is also a guide to the axillary artery during surgery and anesthesia. This additional muscle may cause musculo- cutaneous or high median nerve paralysis. We were unable to find any similar case in the published litera- ture. The anatomic variations of the coracobrachialis muscle may cause confusion during surgery or evalua- tion of CT and MRI scans. The French version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at http:// dx.doi.org/10.1007/s00276-002-0079-5. Un cas rare de muscle coraco-brachial anormal. Revue de la litte´rature Re´ sume´ Au cours de dissections pre´alables destine´es a` rechercher l’incidence du troisie` me chef du muscle biceps brachial sur des cadavres de nouveau-ne´s, un muscle coraco-brachial accessoire ae´te´ trouve´ d’un seul coˆ te´ sur le cadavre d’un garc¸on nouveau-ne´. Le muscle naissait du processus coraco et de la capsule scapulo-hume´rale, il se terminait dans le fascia ante´ brachial et sur l’e´picondyle me´dial de l’hume´rus. Le muscle coraco- brachial est utilise´ comme lambeau dans les de´forma- tions des re´gions infra-claviculaire et axillaire et dans les reconstructions apre`s mastectomie. C’est e´galement un guide pour l’arte`re axillaire en chirurgie et en anesthe´sie. Ce muscle supple´mentaire pourrait entraıˆner une paral- ysie du nerf musculo-cutane´ ou une paralysie haute du nerf me´dian. Nous n’avons pu trouver aucun cas simi- laire dans la litte´rature. Les variations anatomiques du muscle coraco-brachial peuvent entraıˆner des confusions au cours de la chirurgie ou des examens par scanner ou IRM. Keywords Anomaly Æ Coracobrachialis muscle Æ Musculocutaneous nerve Æ Variation Æ Upper extremity Æ Gross anatomy Introduction Several studies have demonstrated variations of the form and origins of the coracobrachialis muscle [2, 3, 9, 15, 36]. In most species, the coracobrachialis has three portions: the longus, medius and brevis. In humans, the medius and longus fuse to form the coracobrachialis [9, 17]. The original third head of the muscle, termed coracobrachialis brevis, occurs rather rarely [2, 9, 17, 36]. It arises from the coracoid process and inserts into the crest of the lesser tubercle or the intertubercular groove and articular capsule of the shoulder joint. Surg Radiol Anat (2002) 24: 406–410 DOI 10.1007/s00276-002-0079-5 C. Kopuz Æ N. _ Ic¸ ten Æ M. Yildirim Presented at the 5th National Symposium of Anatomy with In- ternational Participation, 25–30 September 1999, Antalya, Turkey The French version of this article is available in the form of elec- tronic supplementary material and can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00276- 002-0079-5 C. Kopuz (&) Æ N. _ Ic¸ ten Department of Anatomy, Medical School Ondokuz Mayıs University, Samsun, Turkey E-mail: drcrusta@hotmail.com Tel.: +90-362-4576090 Fax: +90-362-4576090 C. Kopuz Ko¨rfez mah. Atatu¨rk Bulvarı No: 124, 55139 Kurupelit, Samsun, Turkey M. Yildirim Department of Anatomy, Cerrahpasa Medical School Istanbul University, Istanbul, Turkey