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Ankle and Foot Tibia and fibula held together by interosseous membrane; also serves for muscle attachment. Tibia larger and only true weight bearing bone of the leg. Foot is divided into three parts: hindfoot (talus and calcaneus); midfoot (navicular and cuboid) and forefoot (three cuneiforms, five metatarsals and all phalanges. Each plays a specific role during gait. Hindfoot is first to contact ground and "tells" distal parts how to move to prepare for surfaces. Midfoot provides stability and mobility as movement moves from hindfoot to forefoot. Forefoot is last in contact with ground. Ankle and foot perform three main functions: Shock absorber during gait Adapting mechanism during gait Provides stable base of support to move body forward Motions PF, DF on sagittal Inversion and eversion on frontal plane Adduction and abduction on transverse plane Adduction and abduction occur in the forefoot and accompany inversion and eversion Supination is a combination of PF, inversion and adduction Pronation is a combination of DF, eversion and abduction Valgus = distal segment positioned away from midline Varus = distal segment positioned toward midline Superior tibiofibular joint between head of fibula and posterior lateral proximal tibia. Uniaxial plane joint with joint capsule reinforced by ligaments. Has minimal gliding movement. Interior tibiofibular joint is a syndesmosis (fibrous) between distal tibia and distal fibula. No joint capsule. Adds to strength of ankle joint based on its strength. Ankle joint Talocruraal or talotibial consists of distal tibia sitting on talus surrounded by medial/lateral malleolus. Subtalar or talocalcaneal = inferior surface of talus with superior surface of calcaneus. Gliding. Anterior talus and calcaneus articulate with posterior surfaces of navicular and cuboid to make the transverse tarsal joint (midtarsal). Little movement between navicular and cuboid. Pronation and supination (between hindfoot and forefoot) occur here. Functionally the subtalar and transverse tarsal joints cannot be separated so supination/pronation are actually combined motions. DF/PF = talocural joint Inversion/eversion = subtalar and transverse tarsal joints Ligaments Ankle has a joint capsule that is thin anteriorly and posteriorly reinforced by collateral ligaments on sides … actually groups of several ligaments Medially is triangular deltoid ligament that strengthens the medial side of the ankle, holds the calcaneus and navicular against the talus, and helps to maintain the medial longitudinal arch. Laterally is a group of three ligaments referred to as the lateral ligament. Weaker anteriorly, fairly strong posteriorly. Ankle is considered the most frequently injured joint in the body and the lateral ligament is most frequently injured ligament. Arches Foot must absorb great shock, adjust to terrain changes and propel body forward. Bones of foot arranged in arches to assist. Stand on a triangle with weight bearing borne from base of calcaneus to heads of first and fifth metatarsals. Between these points have two arches (medial and lateral longitudinal) at right angles to third (transverse). Medial longitudinal - medial border of foot. Talus is top of the arch and referred to as the keystone. This arch depresses during weight bearing and recoils when weight removed. Lateral longitudinal - normally rests on ground during weight bearing. Transverse arch - second cuneiform is keystone of this arch The three arches maintained by shape of bones and relationships, plantar ligaments and aponerosis and muscles. Ligaments and aponerosis most important features. Spring ligament (plantar calcaneonavicular) most important because it supports the medial side of the longitudinal arch Long plantar ligament is longest and more superficial and spring for primary support of the lateral longitudinal arch Short plantar ligament assists long plantar Longitudinal arch further supported by plantar aponeurosis that acts as a tie rod keeping the posterior segments from separating from the anterior. Arches also supported by muscles but total muscular support to the arches has been estimated to bear only about 15-20% of the total stress to the arches.