MSK Session 12 Flashcards
What is the function of the ankle joint in upright posture?
Bear all body weight as it transfers to foot
What is the clinical importance of the ankle joint?
Arterial pulses of limb can be examined here
Where do venous and lymph drainages undergo particular changes so that their low pressure systems can return fluid to the body?
Ankles
How do arteries, motor nerves and tendons enter the foot?
Turning forwards
How do veins, sensory nerves and lymphatics exit the foot?
Turning upwards
What prevents bow-stringing of the long tendons of leg muscles at the ankle?
Crural fascia
How does the foot support body weight?
Establishes broad base for bearing body weight
Robust
Absorbs shock
What two opposing functions does the foot have?
Supporting body weight and organ of locomotion
What features of the foot allow it to be an organ of locomotion?
Loose to permit movement but stable when moving
Permits movement on flat, sloping and uneven surfaces
Lightweight
Able to lift body weight during initiation of movement
What forms the ankle joint proper?
Articulation of tibia and fibula w/talus
How many articular surfaces are there in the ankle joint proper?
6
What are the articular surfaces of the ankle joint proper lined with?
Hyaline cartilage
What are key landmarks in distal superficial venous drainage of the lower limb?
Malleoli
Where do the tibia and fibula articulate with each other?
Most of their lengths
What is the proximal articulation of the tibia and fibula?
Tibio-fibular articulation
What type of joint is the proximal articulation of the tibia and fibula?
Plane type synovial
What is the intermediate articulation of the tibia and fibula?
Interosseous membrane
What is the distal articulation of the tibia and fibula?
Tibio-fibular syndesmosis
What type of joint is the distal articualtion of the tibia and fibula?
Fibrous
Which two ligaments tie the ends of the tibia and fibula together in the tibio-fibular syndesmosis?
Anterior and posterior tibio-fibular ligaments
Which ligament deepens the articulatory surfaces of the tibio-fibular syndesmosis?
Posterior tibio/fibular
What type of joint is the ankle joint proper?
Mortise and tenon
Ginglymus
Rolling hinge synovial
Why is the ankle joint described as a mortise and tenon joint?
Leg bones form recess (mortise)
Superiorly rounded talus fills recess (tenon)
What allows changes between extremes of plantarflexion and dorsiflexion at the ankle joint?
Superiorly rounded talus allows rolling in a plane
Which are the joint stabilising surfaces of the ankle joint?
Malleolus
Posterior distal tibio-fibular ligament
Transverse tibio-fibular ligament
Which are the weight bearing surfaces of the ankle joint?
Tibia
Talus
(Fibula takes ~17% so contributes to stability)
Which bones of the foot form the medial longitudinal arch?
Calcaneus Talus Navicular 3 cuneiforms 1-3 metatarsals
Which bones of the foot form the lateral longitudinal arch?
Calcaneus
Cuboid
4th + 5th metatarsals
Which bones of the foot form the transverse arch?
Tarsals and metatarsals
What strengthens the transverse arch of the foot?
Long tendon of leg muscles
Why must the segmented structure of the foot be arranged in an arch?
Can only weight bare if in an arch
How many arches are present in the foot at birth?
3
Why may the foot appear flat in children
Subcutaneous fat pad masks arches present
In which two direction are the arches of the foot arranged?
2 antero-posteriorly
1 transverse medio-lateral
What type of attachments does the talus have?
Purely ligamentous
Where is the long axis of the talus directed?
Forwards and medially
What is the significance of the direction of the long axis of the talus?
Tibia and fibular can roll over and direct weight in its deviated path
How is the dorsal aspect of the talus identified?
Superiorly convex medial and lateral edges
Central portion concave
How does the posterior articular surface (body) of the talus compare to the anterior articular surface (head)?
Narrower
What are the three parts of the talus bone?
Head, neck and body
What does the plantar surface of the talus form?
Talo-calcaneal (sub-talar) joints
What is visible on the inferior view of the talus?
Sulcus tali