S5: the lower limb (3) Flashcards
Describe the bones of the foot
Three groups: tarsal bones, metatarsals, phalanges (toes have three phalanges except big toe which has two)
Three regions: hindfoot (talus & calcaneus), midfoot (navicular, cuboid, cuneiforms) & forefoot (metatarsals, phalanges)
Describe the structure of the ankle joint
Synovial joint between the tibia, fibula, and talus
Hinge joint = permitting dorsiflexion and plantarflexion of the foot
Movements: dorsiflexion and plantarflexion ONLY
Describe the bony surfaces that constitute the ankle joint
Tibia and fibula form a bracket-shaped socket known as the mortise
Trochlea of the talus is wedge-shaped – broad anteriorly and narrow posteriorly
Dorsiflexion: anterior part of trochlea is held in the mortise & joint is more stable
Plantarflexion: posterior part of trochlea is held in mortise & joint is less stable
Describe the ligaments associated with the ankle joint and their role in maintaining stability
Lateral ligament has three parts & these resist inversion of the foot
-anterior talofibular ligament: between lateral malleolus and neck of talus
-posterior talofibular ligament: between malleolar fossa and lateral tubercle of talus
-calcaneofibular ligament: between tip of lateral malleolus & lateral surface of the calcaneus
Medial (deltoid) ligament is stronger & resists excessive eversion of the foot
Describe the joints of the foot and their respective movements
Inversion & eversion occurs at the subtalar, calcaneocuboid and the talocalcaneonavicular joints
Function significance of inversion & eversion is to allow walking on uneven surfaces
Subtalar is the major joint where these movements occur
List the movements of the ankle and subtalar joints and which muscles contribute to these actions
Plantarflexion = posterior compartment of the leg: gastrocnemius, soleus, plantaris & tibialis posterior Dorsiflexion = anterior compartment of the leg: tibialis anterior, extensor hallucis longus, extensor digitorum longus & peroneus tertius Eversion = lateral compartment of the leg: peroneus longus & peroneus brevis; also, peroneus tertius from anterior compartment Inversion = tibialis anterior & tibialis posterior
Name the origins, insertions, blood supply and innervation of the anterior compartment of the leg
All originate (except TA & EDL) at medial surface of the fibular shaft Blood supply: anterior tibial artery Innervation: deep peroneal nerve Action: dorsiflexion of the foot Tibialis anterior = origin: lateral surface of tibia, insertion: medial cuneiform & base of 1st metatarsal, action: also inversion of foot Extensor digitorum longus = origin: lateral condyle of tibia & interosseous membrane, insertion: middle/distal phalanges of the 2nd to 5th toes, action: also extension of lateral four toes Extensor hallucis longus = insertion: distal phalanx of the great toe, action: also extension of big toe Peroneus tertius = insertion: base of the 5th metatarsal; action: also eversion of foot
Name the origins, insertions and innervation of the lateral compartment of the leg
Innervation: superficial peroneal nerve
Action: eversion of the foot
Peroneus longus = origin: upper lateral surface of the fibula & lateral tibial condyle, insertion: plantar surface of the medial cuneiform & base of the 1st metatarsal, action: plantarflexes foot
Peroneus brevis = origin: inferolateral surface of the fibular shaft, insertion: tubercle on the base of the 5th metatarsal
Name the origins, insertions and innervation of the (superficial) posterior compartment of the leg
Insertion: form calcaneal tendon -> inserts on calcaneal tuberosity
Innervation: tibial nerve
Action: plantarflexes foot
Gastrocnemius = origin: lateral head at lateral femoral condyle & medial head at medial femoral condyle, action: assists in knee flexion
Plantaris = origin: lateral supracondylar line of the femur, action: weak plantarflexor & knee flexor
Soleus = origin: soleal line of the tibia
Name the origins, insertions and innervation of the (deep) posterior compartment of the leg
Innervation: tibial nerve
Popliteus = origin: interosseus membrane & posterior surfaces between the tibia/fibula, insertion: tibia proximal to soleal line, action: ‘unlocking’ the knee so that flexion can occur
Tibialis posterior = origin: lateral condyle of the femur & horn of the lateral meniscus, insertion: plantar surface of the navicular & medial cuneiform bones, action: plantarflexes and inverts the foot
Flexor digitorum longus = origin: medial surface of tibia, insertion: base of the distal phalanx of each of the lateral 4 digits, action: flexes the lateral 4 toes
Flexor hallucis longus = origin: posterior surface of fibula, insertion: plantar surface of the base of the distal phalanx of the big toe, action: flexes big toe
Describe the anatomy and role of the medial longitudinal arch of the foot
Formed by the calcaneus, talus, navicular, three cuneiforms & medial three metatarsals
Plantar aponeurosis, spring ligament, tibialis anterior and peroneus longus tendons play major roles in maintaining the integrity of this arch
Absent in flat feet (medial arch has collapsed so that medial border of the foot almost touches the ground)
Define gait
Gait is the mechanism by which the body is transported using co-ordinated movements of the major lower limb joints
Describe the phases of the gait cycle
Stance phase = initial contact, loading response, mid-stance, terminal stance, pre-swing
Swing phase = initial swing, mid-swing, terminal swing
Define step, stride and cadence
Step = the distance from initial contact with one leg to initial contact with the opposite leg Stride = the distance from initial contact with one leg to the next initial contact with the same leg Cadence = number of steps per minute
Describe the differences between walking and running
Walking = double support when both feet are in contact with the ground, more stance phase (60%) than swing phase (40%) Running = doubles float when both feet are in the air, the length of stance and swing phases opposite to walking
