The flexor compartment muscles of the arm comprising of biceps brachii, brachialis and the coracobrachialis are innervated by the musculocutaneous nerve arising from the lateral cord of the brachial plexus. In the present study, we report a case of anomalous innervation of the corachobrachialis muscle on the left side of a 45-year-old male cadaver. The musculocutaneous nerve originated from the lateral cord, as usual and pierced the corachobrachialis muscle. The median nerve was formed by a contribution from both lateral and medial roots, both of which took origin from the lateral and medial cords, respectively. In addition to the usual musculocutaneous nerve which pierced the corachobrachialis muscle and innervated it, two more anomalous branches from the median nerve were observed to innervate the corachobrachialis. The anatomical knowledge of the variations of the innervations of the corachobrachialis muscle may be important not only for surgeons performing coracoid transfer but also for clinicians diagnosing nerve lesions.
During routine dissection classes to undergraduate medical students, we have observed some important anatomic variations in the right upper limb of a 45-year-old cadaver. The anomalies were superficial ulnar artery, persistent median artery, variant superficial palmar arch, third head for biceps brachii, accessory head for flexor pollicis longus, variant insertion of pectoralis major, absence of musculocutaneous nerve, coracobrachialis muscle supplied by lateral root of median nerve and anomalous branching of median nerve in arm and forearm. Although there are individual reports about these variations, the combination of these variations in one cadaver has not previously been described in the literature consulted. Awareness of these variations is necessary to avoid complications during radiodiagnostic procedures or surgeries in the upper limb.
The presence of anatomical variations of the peripheral nervous system often accounts for unexpected clinical signs and symptoms. We report unusual variations of the lateral and posterior cords of the brachial plexus in a female cadaver. Such variations are attributed to a faulty union of divisions of the brachial plexus during the embryonic period. The median nerve lay medial to the axillary artery (AA) on both sides. On the right, the lateral root of the median nerve crossing the AA and the median nerve in relation to the medial side of the AA was likely the result of a faulty development of the seventh intersegmental artery. We discuss these variations and compare them with the findings of other researchers. Knowledge of such rare variations is clinically important, aiding radiologists, anaesthesiologists and surgeons to avoid inadvertent damage to nerves and the AA during blocks and surgical interventions.