Download TSM100 - Leg 1 and Ankle Joint

TSM100: ANTERIOR AND LATERAL LEG AND ANKLE JOINT
09/12/08
LEARNING OUTCOMES
Describe the superior and inferior tibiofibular joints
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The bony structure of the leg comprises the tibia medially and the fibula laterally
o The tibia is the weight-bearing bone of the leg and articulates at the knee and ankle
o The fibula is smaller, articulates mainly with the tibia and forms a part of the ankle
o A strong interosseous membrane holds the two leg bones together along most of their length
There are two tibiofibular joints, one at each end of the leg:
o Superior – fibular head and lateral tibial condyle; common fibular nerve passes inferiorly
o Inferior – syndesmosis of interosseous ligament; extremely strong; strengthens ankle joint
Describe the functional and clinical anatomy of the ankle joint
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The ankle joint is the point of articulation between the distal tibia, fibula and the talus tarsal bone
o The distal leg bones each feature malleoli – projections which form an arch at the ankle
o Hinge type synovial joint about the trochlear surface of the talus
There are seven tarsal bones that make up the proximal foot:
o Proximal row (lateral to medial)
 Calcaneus – largest tarsal bone; forms heel of foot; sustentaculum tali medially
 Talus – most superior tarsal bone; articulates with the tibia and fibula
o Distal row (lateral to medial)
 Cuboid – joins with the calcaneus posteriorly
 Cuneiforms – three spanning to the medial border of the foot
 Navicular – between the cuneiforms anteriorly and talus posteriorly
The five metatarsals articulate posteriorly with the distal tarsal bones:
o Medial three metatarsals (1 to 3) are joined to the three cuneiforms
o Lateral two metatarsals (4 and 5) are both joined to the cuboid
There are two sets of ligaments that support the ankle joint:
o Medial – ‘deltoid’; larger and stronger of the two; four components:
 Tibionavicular
 Tibiocalcaneal
 Tibiotalar (anterior and posterior)
o Lateral – three components:
 Talofibular (anterior and posterior)
 Calcaneofibular
Demonstrate the range of normal movements of the ankle joint
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The ankle joint allows up to 30˚ dorsiflexion (‘extension’) and up to 50˚ plantarflexion
The muscles of the leg are contained within three compartments:
o Anterior – ankle dorsiflexors and toe extensors
o Lateral – minor compartment; foot evertors (other two compartments involve invertors)
o Posterior – ankle plantarflexors and toe flexors
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There are three main muscles in the anterior compartment:
o Tibialis anterior – most anterior; from lateral tibia crossing medially to medial cuneiform
o Extensor hallucis longus – deep to tibialis anterior; inserts on dorsal distal phalanx of 1st digit
o Extensor digitorum longus – most lateral; inserts on dorsal distal phalanges of 2nd to 4th digits
o All the above are supplied by the anterior tibial artery and deep peroneal nerve
There are two muscles in the lateral compartment:
o Fibularis longus – more superficial; from proximal fibular head to inferior medial cuneiform
o FIbularis brevis – deeper; from mid-fibula to lateral tubercle of 5th metatarsal
o All of the above are supplied by the fibular artery and superficial peroneal nerve