Figure 8
Measurement and calculation of muscle geometry of medial Gastrocnemius muscle within its mid-longitudinal fascicle plane. (A) The mid-longitudinal fascicle plane, determined with 3D ultrasound. The medial Gastrocnemius muscle (MGM) is covered by the subcutis (SUB) and supported by Soleus muscle (SM). Parts of both femur (fem) and tibia (tib) are shown. The black dotted lines define the outline of the muscle. The most distal muscle belly end is indicated by a black arrow. The length of the target fascicle (ℓ(fasc)) (dashed black line), centred at 2/3rd (*) of muscle belly length (from the origin) is measured. Muscle thickness (ℓ(m th)) was calculated as the distance between the proximal and the distal aponeurosis at the proximal end of the target fascicle (left black double arrow). The fascicle-aponeurosis angle (γ (fasc) ) was calculated as the mean of the angles of the fascicle with the proximal and distal aponeurosis (black arcs). Scale bar depicts 1 cm. (B) Schematic overview of morphological muscle parameters in the mid-longitudinal fascicle plane of the medial Gastrocnemius muscle. The length of the aponeurosis (ℓa) and the length of the physiological cross-sectional area (ℓAf) will be calculated from this model. The muscle belly length (ℓm) will be measured from the origin at the femur condyle to the distal end of the muscle belly. The tendon length (ℓt) will be measured from the distal muscle belly end to the insertion at the calcaneus.