MSK - Bones of the Foot Flashcards
What are the bones in the proximal section of the foot?
- Talus
- Calcaneus
What is the function of the talus?
Transmission of forces from the tibia to the calneus (heel bone)
What are the three articulations of the talus?
- Ankle joint = superiorly (talus, tibia and fibula)
- Subtalar joint = inferiorly (talus and calcaneus)
- Talonavicular joint = anteriorly (talus and calcaneus)
What is the function of the calcaneus?
Transmission of forces from the talus to the ground
What are the two articulations of the calcaneus?
- Subtalar joint = superiorly (calcaneus and talus)
- Calcaneocuboid joint = anteriorly (calcaneus and cuboid)
What is the bone in the intermediate row of tarsal bones?
The navicular
What are the three articulations of the navicular?
- Talus (posteriorly)
- Cuneiform (anteriorly)
- Cuboid (laterally)
What is the feature of the plantar surface of the navicular?
A tuberosity for the attachment of the tibialis posterior tendon
What are the four bones of the distal group of tarsal bones? (lateral to medial)
- Cuboid
- 3 Cuneiforms
What are the 2 articulations of the cuboid?
- Calcaneous (posteriorly)
- Two metatarsals (4 and 5) (anteriorly)
What is a feature of the inferior surface of the cuboid?
A groove for the fibularis longus muscle
What are the articulations of the three cuneiforms?
- Navicular (posteriorly)
- Metatarsals (anteriorly)
What does the shape of the cuneiform bones form?
A transverse arch
Which are the most commonly fractured bones of the foot?
- Talus
- Calcaneus
How are fractures to the neck of the talus caused?
- Excessive dorsiflexion of the foot
- Pushes the neck of the talus against the tibia
What can a fracture to the neck of the talus result?
Avascular necrosis of the bone as the blood supply may be disturbed
How are fractures to the body of the talus caused?
Usually from jumping from a height
Why is there little displacement of pieces when the talus is fractured?
The malleoli of the leg bones holds the fragments together
How are fractures to the calcaneus caused?
- Usually in ‘crush’ type injuries e.g. falling from a height onto the heel
- Drives talus into the calcaneus
- Comminuted fracture
How can calcaneal fractures cause further problems, even after treatment?
- Disruption of the sub-talar joint = becomes arthritic
- Pain during inversion/eversion
- Painful to walk on uneven ground
Where are the metatarsals located and how are they numbered?
- Midfoot, between the tarsals and phalanges
- Numbered 1-5, medial to lateral
Describe the structure of a metatarsal
- Has a distal head and a proximal base
- Joined by a shaft of bone
What is the proximal articulation of the metatarsals?
- Tarsometatarsal joint
- Between metatarsal bases and cuneiforms/cuboid
What is the lateral articulation of the metatarsals?
- Intermetatarsal joint(s)
- Between metatarsal and adjacent metatarsals
What is the distal articulation of the metatarsals?
- Metatarsophalangeal joint
- Between metatarsal head and proximal phalanx
What is the most common way of fracturing a metatarsal?
Direct blow to the foot e.g. dropping a heavy object
How are stress fractures of the metatarsals caused?
- Repeated stress to the bone
- Fracture is incomplete
Where is the most common location of stress fractures to the metatarsals? Who are they most likely to affect?
- Metatarsals 2, 3 and 4
- Athletes
How can excessive inversion of the foot fracture the metatarsals?
Fibularis brevis can avulse/tear off the base of metatarsal 5 if the foot is violently inverted
Describe the organisation of the phalanges in the foot
- Big toe only has a proximal and distal phalanges
- Rest of toes have a proximal, intermediate and distal phalanges
