MSK 10 - Anatomy of the Leg, Foot + Ankle Joint

Question 1

What forms the ankle joint?
What type of joint is the ankle?
What are the outgrowths of the tibia and fibula called?

Answer 1

• The ankle is specifically the articulation between the tibia, fibula and talus of the foot.
• A mortise + tenon joint - tibia + fibula have inferior outgrowths that form the mortise for the talus (tenon) to fit in.
• Lateral malleolus (fibula) + medial malleolus (tibia)

Question 2

Describe the bony anatomy of the foot from the talus upwards.

Answer 2

• Talus articulates articulates w/a number of bones, in particular the calcaneus (via sub-talar joint)
• Navicular communicates with the 3 cuneiforms + cuboid
• 3 x cuneiforms (medial, intermediate + lateral) articulate with the metatarsals. Lateral cuneiform articulates with cuboid bone.
• Metatarsals articulate with the phalanges (proximal –> middle –> distal).

Question 3

What are the major movements of the foot + ankle?

Which joints provide these movements?

Answer 3

1) Plantar/dorsiflexion - via ankle joint (plantar dominant)
2) Inversion/eversion - via subtalar joint (eversion dominant)

• Can show this by doing the movements yourself

Question 4

Which muscle groups produce the 4 main movements of the foot + ankle?

Answer 4

1) Plantarflexion = those running posterior to the malleoli (posterior + lateral compartments of leg)
2) Dorsiflexion = those running anterior to the malleoli (anterior compartment)
3) Inversion = those running along medial aspect of the foot (posterior compartment of leg)
4) Eversion = those running along lateral aspect of foot (lateral compartment of leg).

Question 5

What nerve supplies the posterior leg compartment?
What movements do the posterior leg compartment provide?
What are the key muscles of the posterior leg compartment?

Answer 5

• Posterior leg supplied by tibial nerve
• Produces plantarflexion + inversion
• Gastrocnemius + Soleus = plantarflexion
• Tibialis posterior, Flexor Hallucis Longus + Flexor digitorum longus = inversion

Question 6

What nerve supplies the anterior leg compartment?
What movement does the anterior leg compartment supply?
Which muscles are involved in this movement?

Answer 6

• Anterior leg supplied by the deep fibula nerve
• Primarily involved in dorsiflexion
• Tibialis anterior/Extensor digitorum longis/Fibularis tertius.

Question 7

What nerve supplies the lateral leg compartment?
Which movements does the lateral leg supply?
What are the 2 muscles in this compartment?

Answer 7

• Superficial fibular nerve
• Eversion + plantarflexion
• Fibularis longus + Fibularis brevis

Question 8

What 4 features provide stability to the ankle joint?

Answer 8

1) Bones
2) Joint capsule
3) Ligaments
4) Muscles

Question 9

How does the talus bone provide stability to the ankle joint during dorsiflexion?

Answer 9

• The talus is tapered (narrowing at posterior aspect), giving stability during dorsiflexion.
• This is why most injuries occur during plantarflexion

Question 10

What is the role of ligaments around the ankle joint?

Answer 10

• The ankle is a hinge joint, meaning movement occurs in one plane only.
• All hinge joints possess collateral ligaments for stability, which keep movement within a single plane.
• The ankle ligaments prevent hyperplantar and hyperdorsiflexion as well as hyper-inversion/eversion. (Remember that ligaments tend to limit movements).

Question 11

Which ligaments “glue” the tibia + fibula together?
What are the 3 ligaments in the deltoid ligament complex on the posteromedial aspect of the ankle joint + what is their role?

Answer 11

• The anterior + posterior tibiofibular ligaments.

1) Tibiocalcaneal (tibia to calcaneus)
2) Tibionavicular (tibia to navicula)
3) Anterior tibiotalar (tibia to talus)
- These 3 ligaments limit eversion.

Question 12

What ligaments on the lateral aspect of the ankle joint limit inversion?

Answer 12

• Anterior + posterior talofibular ligaments

- Calcaenofibular ligaments

Question 13

How do the tendons of the muscles provide stability to the ankle joint?

Answer 13

• The tibialis anterior + posterior tendons (medial) + fibularis longus tendon (lateral) provide in inbuilt “stirrup” in the foot, which helps maintain the arch and provide stability.

Question 14

Which 5 structures run through the tarsal tunnel in the ankle joint? (Use Tom, Dick + A Nervous Harry pneumonic)
Which tendon underneath the tunnel holds these structures in place?

Answer 14

1) Tendon of flexor tibialis posterior (Tom)
2) Tendon of flexor digitorum longus (Dick)
3) Posterior tibial artery (A)
4) Tibial nerve (Nervous)
5) Tendon of flexor hallucis longus (Harry)

• The flexor retinaculum

Question 15

Which ligament is most likely to be ruptured in forced inversion?

Answer 15

• The anterior talofibular ligament