Additional head of biceps brachii: a cadaveric study

Background: The biceps brachii is an important muscle of anterior compartment of arm. It shows frequent anatomic variability due to presence of supernumerary heads. Knowledge of the existence of the third head of biceps brachii is important for surgeons. Keeping this in mind a study was planned to see the incidence of additional head of biceps brachii in sample Indian population and to compare it with other racial groups.Methods: The study was carried out on 30 cadaveric upper limbs. The upper limbs were dissected and studied for the presence of additional head of biceps brachii. The attachment and nerve supply of the additional head was carefully observed, recorded and documented.Results: Out of 30 limbs which were dissected, additional head of biceps brachii was found only in two limbs. In both the cases the additional head was present only on the right side and arose from the anterior surface of humerus, superomedial to the origin of brachialis. The additional head fused with the common bulk of the muscle and was inserted into the radial tuberosity and bicipital aponeurosis. The extra heads of biceps brachii muscle received branches from musculocutaneous nerve.Conclusions: Biceps brachii is one of the commonest muscles showing variations. The additional head is not only of academic importance, but its knowledge also helps clinicians in managing fractures of humerus and nerve entrapment.

Bipartite clavicular attachment of the sternocleidomastoid muscle: a case report / 대한해부학회지

Morphological variations of the sternocleidomastoid (SCM) muscle assume relevance during attempted surgical interventions in the cervical region. The present study reports bipartite clavicular attachment of the SCM in the neck of an adult male cadaver during performance of a routine anatomy demonstration. The anomaly was unilaterally observed on the left side of the neck. The clavicular head of the muscle exhibited two bellies, one medial and one lateral. While the medial belly was fused with the sternal head, the lateral belly appeared to blend with the medial. Cranially, the SCM attached to the mastoid process and superior nuchal line. We have attempted to elucidate the embryological basis of the above muscular variant. Additionally, we discuss its clinical relevance, highlighting the utility of the SCM in various reconstructive procedures. We assert that detailed anatomical knowledge of such SCM variants is of utility not only to the gross anatomist, but also for neck and orthopaedic surgeons and anaesthetists. Moreover, radiologists require familiarity with such aberrations to decipher magnetic resonance imaging scans of the cervical region.