Figure 1. View of the thenar, transverse plane. FPB: flexor pollicis brevis muscle, FPL: flexor pollicis longus tendon, I. MTC: first metacarpal
Transverse ultrasound section through the thenar region. The flexor pollicis brevis muscle (FPB) is visible superficially, with the flexor pollicis longus tendon (FPL) located within its muscle belly, appearing as a markedly hyperechoic oval structure. The bony interface of the first metacarpal (I. MTC) is visible laterally, serving as the main landmark for this projection. This projection allows clear visualization of the superficial soft tissue structures of the thenar and is useful in evaluating pathology of the FPL tendon and thumb muscles.
Figure 2. View of the thenar, sagittal plane. FPB: m. flexor pollicis brevis, FPL: tendon of m. flexor pollicis longus, I. MTC: first metacarpal
Longitudinal ultrasound section through the thenar region showing the m. flexor pollicis brevis (FPB) and the tendon of m. flexor pollicis longus (FPL) running along the first metacarpal (I. MTC). The FPL tendon is visible in this projection in long axis as a linear fibrillar structure located between the soft tissues of the thenar and the bony interface of the first metacarpal. This projection is suitable for dynamic examination of the FPL tendon during flexion in the interphalangeal joint of the thumb and allows assessment of its continuity, gliding, and any pathological changes.
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