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I t p a y s t o b e A B M P C e r t i f i e d : w w w. a b m p . c o m / g o / c e r t i f i e d c e n t r a l 105 I t p a y s t o b e A B M P C e r t i f i e d : w w w. a b m p . c o m / g o / c e r t i f i e d c e n t r a l 105 The subtalar joint is an ellipsoid joint between the talus and calcaneus. It is also called the "lower ankle joint" because it moves with the talocrural joint during inversion and eversion, and allows movement of the ankle in all three planes. JOINTS OF THE MIDFOOT The midfoot is built for stability and spring. Its tarsal bones have relatively flat articular surfaces that fit closely together to form a series of transverse and longitudinal arches. The transverse tarsal joint divides the rearfoot from the midfoot. It is actually two joints that move together: the talonavicular and calcaneocuboid. Also called the midtarsal joint, this S-shaped articulation is mechanically linked to, and moves with, the subtalar joint. A number of intertarsal (IT) joints occupy the spaces between the five tarsal bones: the cuboid, the three cuneiforms, and the navicular. These gliding joints have minimal motion, particularly across the transverse arch of the midfoot; this arch is locked into place by the wedged position of middle cuneiform between the other cuneiforms, which prevents it from collapsing. The tarsometatarsal (TMT) joints connect the distal row of tarsals to the long metatarsal bones, forming five functional units called "rays" that transfer weight into the toes. The many joints in the midfoot work like a bony spring, letting the arches slightly flatten under load, then spring back, providing elastic energy for walking. JOINTS OF THE FOREFOOT The five metatarsophalangeal (MTP) joints are ellipsoid joints connecting the metatarsal bones to the proximal phalanges. The MTPs can flex and extend, providing leverage for push-off in gait; they can also abduct and adduct, allowing the toes to spread or pull together. Fourteen interphalangeal (IP) joints provide hinge articulations that allow flexion and extension of the toes. Flexibility can be restored to fallen arches with range of motion exercises for the rearfoot and midfoot, both active and passive. Next Issue: Spring in the Arches Exploring Technique Passive Rear foot and Midfoot Motion 1. Rearfoot: Hold the sides of the calcaneous with one hand and the midfoot with the other hand, then lightly traction the subtalar joint. Maintain light traction while passively inverting and everting the ankle (Image 4). Avoid twisting the forefoot to limit motion to the subtalar and midtarsal joints. 2. Midfoot: Move the tarsometatarsal (TMT) joints by grasping the tarsals with one hand and the metatarsal shafts with the other hand. Slowly press with firm pressure and lift the tarsal bones while simultaneously pressing down on the metatarsals, then reverse the action (Image 5). In healthy, flexible feet, there will be a slight gliding motion between the tarsals. In rigid feet, TMT movement is difficult to facilitate and requires advanced skills. Mary Ann Foster is the author of Therapeutic Kinesiology: Musculoskeletal Systems, Palpation, and Body Mechanics (Pearson Publishing, 2013). She can be contacted at mafoster@ somatic-patterning.com. 3 Major bones and joints of the ankle and foot. Metatarsophalangeal (MTP) joints Tarsometatarsal (TMT) joints Navicular bone Cuneiforms Talus Calcaneus Transverse tarsal (Midtarsal) joint Cuboid 4 5