Lecture - The Ankle Joint Flashcards
What shape is the socket formed by the tibia and fibula?
A bracket (mortise) shape
How are the tibia and fibula bound together at the ankle joint?
By strong tibiofibular ligaments
What are the two major groups of ligaments involved in the ankle joint?
Medial and lateral ligaments
Where does the medial ligament originate from?
Where do they end up?
The medial malleolus
Calcaneus, navicular and talus
What is the major function of the medial ligament of the ankle?
Resists over-eversion
Where does the lateral ligament originate?
Where does it end up?
Lateral malleolus
Talus and calcaneus
Explain why the ankle joint can be thought of as a “ring”
In the coronal plane, the ankle bones and ligaments can be visualised in a ring -
Upper part = tib/fib
Lower part = subtalar joint
Sides = medial and lateral ligaments
Why is the fact that the ankle forms a ring clinically relevant?
Unlikely to break in only one place
What sort of joint is the ankle joint?
hinge type synovial joint
How many planes of movement are possible at the ankle?
What movements are they?
Just one
Plantarflexion/dorsiflexion
Which muscles allow plantarflexion of the foot?
Gastrocnemius
Soleus
Plantaris
Posterior tibialis
Which muscles produce dorsiflexion of the foot?
Tibialis anterior
Extensor hallucis longus
Extensor digitorum longus
Does the ankle joint perform eversion and inversion of the foot?
No - subtalar joint
Which muscles allow eversion of the foot?
Fibularis longus and brevis
Which muscles allow inversion of the foot?
Tibialis anterior and posterior
When does an ankle sprain usually occur? Why?
When foot is over-inverted
Over-inversion prevented by the lateral ligament but this is weaker than the medial ligament
What is a Pott’s fracture?
Why does it usually occur?
Fracture of both malleoli and the distal tibia
Due to over-eversion of foot
Describe the sequence of events that result in a Pott’s fracture.
Forced eversion pulls the medial ligament, producing avulsion fracture of medial malleolus
Talus moves laterally - breaks off lateral malleolus
Tibia is forced anteriorly - shears off distal tibia against talus
Which bones articulate to form the ankle joint?
The tibia, fibula and talus
