The architecture of the 6-month-old gastrocnemius: a 3D volumetric study

ABSTRACT

Gastrocnemius is essential in normal gait, contributing to the control of ankle plantar flexion and knee flexion. However, there is a paucity of literature on the architecture of the infant gastrocnemius muscle prior to the onset of weight-bearing and gait. This study investigates the three-dimensional (3D) musculoaponeurotic architecture of the gastrocnemius in a six-month-old infant. One six-month-old cadaver was used in this study (The University of Toronto Health Sciences Research Ethics Board, #32679, and The University of Auckland Human Participants Ethics Committee, #016164). Medial (MG) and lateral (LG) heads of the gastrocnemius were serially dissected and a Microscribe G2X(TM) digitizer used to digitize fiber bundles, aponeuroses and tendons. Data were then exported to Autodesk(R) Maya(R) to create 3D models. Custom software quantified architectural parameters, including fiber bundle length, pennation angle, physiological cross-sectional area, and muscle volume. The intramuscular architecture was assessed to determine whether musculoapo-neurotic partitions were present. Muscle volume was <1cm3 for both MG and LG. Three architectural partitions, proximal, middle, and distal, were identified for both MG and LG. Notably, the proximal partitions of both MG and LG had mean fiber bundle length at 2.21 ± 0.41 cm and 2.22 ± 0.27 cm, significantly greater (p < 0.05) than the middle and the distal partitions. The results of this study suggest that both MG and LG have architectural partitions before the commencement of gait. Further longitudinal studies with larger sample sizes are needed to confirm the presence of these architectural partitions, as well as to investigate their growth across the developmental spectrum

RESUMEN

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