Ankle Joint Flashcards
What kind of joint is the ankle?
Synovial joint
What is the ankle formed by?
The bones of the leg and foot- the tibia, fibula and talus
Functionally, what type of joint is the ankle?
Hinge
What does the ankle joint permit?
Dorsiflexion and plantarflexion of the foot
How are the tibia and fibula bound together?
By strong tibiofibular ligaments
What is produced by the tibiofibular ligamental binding of the tibia and fibula?
It produces a bracket shaped socket
What is the bracket shaped socket of the tibia and fibula known as?
A mortise
What is the mortise covered in?
Hyaline cartilage
What fits into the mortise?
The body of the talus
What shape is the articulating part of the talus?
Wedge shaped. Wider anteriorly, and thinner posteriorly
What happens during dorsiflexion?
The anterior part of the bone is held in the mortise, and the joint is more stable
Where do the ligaments of the ankle originate from?
Each malleolus
What are the ligaments of the ankle?
Medial ligament
Lateral ligament
What does the medial ligament attach to?
The medial malleolus
What does the medial ligament consist of?
Four separate ligaments
What happens to the four medial ligaments?
They fan out from the malleolus, attaching to the talus, calcaneus and navicular bones
What is the primary action of the medial ligament?
To resist the over-eversion of the foot
What does the lateral ligament originate from?
The lateral malleolus
What does the lateral ligament do?
Resists over-inversion of the foot
What is the lateral ligament comprised of?
Three distinct and separate ligaments- anterior talofibular, posterior talofibular and calcaneofibular
Where does the anterior talofibular ligament span between?
The lateral malleolus and lateral aspect of the talus
What does the posterior talofibular ligament span between?
The lateral malleolus and posterior aspect of the talus
What does the calcaneofibular ligament span between?
The lateral malleolus
How can the ankle joint and associated ligaments be visualised?
As a ring in the coronal plane
What is the upper part of the ring of the ankle joint formed by?
The articular surfaces of the tibia and fibula
What is the lower part of the ring of the ankle joint formed by?
The subtalar joint (between the talus and calcaneus)
What are the sides of the ring of the ankle joint formed by?
The medial and lateral ligament
What is the result of the ankle joint being a ring?
A ring, when broken, usually breaks in two place. When dealing with an injury to an ankle joint, a clinician must bear this in mind
What type of joint is the ankle joint?
Hinge type
What is the result of the ankle joint being a hinge type joint?
Movement is only possible in one plane
What movements occur at the anlke?
Plantarflexion
Dorsiflexion
What is plantarflexion at the ankle produced by?
The muscles in the posterior compartment of the leg- gastrocnemius, soleus, plantaris and tibialis posterior
What is dorsiflexion produced by?
The muscles in the anterior compartment of the leg- tibialis anterior, extensor hallucis longus, and extensor digitorum longus
What does an ankle sprain refer to?
Partial or complete tears of the ligaments of the ankle joint
What do ankle sprains usually occur in?
A plantarflexed weightbearing foot, which is excessively inverted
Which ligament is more likely to be damaged in an ankle sprain?
The lateral ligament
Why is the lateral ligament more likely to be damaged in an ankle sprain?
It’s weaker
The lateral ligament resists inversion
Which lateral ligament is at the most risk of irreversible damage in an ankle sprain?
The anterior talofibular
What is a Pott’s fracture?
A term used to describe a bimalleolar (medial and lateral malleoli) or trimalleolar (medial and lateral malleoli, and distal tibia) fracture
What is a Pott’s fracture produced by?
Forced eversion of the foot
What stages does a Pott’s fracture occur in?
Forced eversion pulls on the medial ligaments, producing an avulsion fracture of the medial malleolus
The talus moves laterally, breaking off the lateral malleolus
The tibia is then forced anteriorly, shearing off the distal and posterior part against the talus
