Figure 1. Ventral view, transverse plane. LHBB: muscle belly of the long head of biceps brachii, SHBB: muscle belly of the short head of biceps brachii
The transverse ultrasound section through the middle portion of biceps brachii shows muscle bellies of the long and short heads of the biceps. The muscle tissue has the typical "starry sky" appearance, where hypoechoic muscle fibers are interspersed with fine hyperechoic septa of connective tissue and perimysium, creating the finely granular pattern of healthy muscle. The long head (LHBB) is positioned laterally, the short head (SHBB) medially. The humerus is visible in the depth. This view is suitable for evaluating symmetry, volume and echotexture of muscle tissue and for detecting edema, atrophy or focal lesions.
Figure 2. Ventral view, transverse plane. b: biceps brachii tendon, brachialis: m. brachialis
A more distal transverse ultrasound section through the anterior arm displays the superficially located biceps brachii tendon (b) as a hyperechoic fibrillar structure. Beneath it, the m. brachialis is visible, appearing as a broader, less echogenic muscle belly in close relation to the humerus. Clear differentiation of the biceps tendon from the deeper m. brachialis enables precise orientation in this area and is important for evaluating tendon injuries, myotendinous lesions, and fluid collections between muscle layers.
Figure 3. Ventral view, longitudinal plane. biceps: m. biceps brachii
Longitudinal ultrasound section of the distal portion of m. biceps brachii shows the distal myotendinous junction, where muscle fibers gradually narrow and transition into the distal tendon. The tendon appears as a well-defined hyperechoic fibrillar structure extending distally to its insertion. Proximally, the transition of muscle tissue into this dense, regularly organized fibrillar architecture is evident. Deeper lies the m. brachialis, which has lower echogenicity compared to the tendon. This projection is important for evaluating partial and complete lesions of the myotendinous junction, monitoring healing, and planning further treatment or rehabilitation.
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