Final answer:
The close packed position of the subtalar joint, the articulation between the talus and calcaneus bones, is when the foot is in maximal inversion, providing stability and supporting ligaments are taut. This position enables inversion and eversion movements of the foot, which are essential for adapting to uneven terrain and shock absorption during walking.
Step-by-step explanation:
The close packed position of the subtalar joint, which is also called the subtalar joint, refers to the maximally congruent and stable positioning where the joint capsules and supporting ligaments are taut. This position typically occurs when the foot is in maximal inversion. The subtalar joint, an articulation between the talus and calcaneus bones of the foot, allows for gliding movements that contribute to inversion and eversion of the foot. Inversions and eversions are movements that tilt the sole of the foot towards (inversion) or away from (eversion) the midline of the body. This function is critical as it contributes to the ability to walk on uneven ground and helps in the absorption of shock during locomotion.
Ligaments that unite the medial or lateral malleolus with the talus and calcaneus bones serve to support the subtalar joint and resist excess eversion or inversion. Additionally, movement at the subtalar and intertarsal joints all contribute to the production of these pivotal foot movements. Gliding motions at the subtalar joint are facilitated by the plane joints between the tarsal bones, which include the joints between the talus and navicular bones and the calcaneus and cuboid bones. These joints work together to produce the complex motions of foot inversion and eversion.