Distal biceps brachii anatomy and the added value of musculoskeletal ultrasound

The distal biceps brachii tendon (DBBT) is hyperechogenic and ovoid; it has two main components corresponding to the continuation of the short (SH) and long (LH) head biceps brachii myotendinous junctions. As the tendon transitions to deeper planes towards its attachment at the radial tuberosity, it rotates 90° and the DBBT-LH becomes deep to the DBBT-SH. However, the distal attachment of the biceps brachii is not only composed of the DBBT but also by a bicipital aponeurotic expansion commonly known as bicipital aponeurosis, or lacertus fibrosus (LF), which reinforces the cubital fossa, and helps to protect the brachial artery and the median nerve running underneath.

Blasi et al. (2019) conclude that high-resolution musculoskeletal ultrasound is a reliable tool to morphometrically examine the distal biceps components, including the LF. Also, the advantages of identifying the LF in the clinical setting should be considered to further clarify controversies about its implication in DBBT injuries, whether it should be surgically repaired when torn, the evaluation of the LF as it may be used as a reconstruction graft in chronic distal biceps tears, and its role in median nerve and brachial vascular entrapment syndromes.

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