The Leg, Ankle, and Foot

Question 1

What vessel passes through the interosseous membrane between the tibia and fibula?

Answer 1

Anterior tibial artery

Question 2

What land mark is found on the posterior aspect of the tibia?

Answer 2

The soleal line and oblique impression on the back off the bone near its upper end

Question 3

What two joints unite the tibia and fibula?

Answer 3

The proximal tibiofibular joint- a synovial joint between the fibula head and the lateral tibial condyle

The distal tibiofibular joint- a strong firbous joint

Question 4

What additional structures exist to hold the tibia and fibula together?

Answer 4

Anterior and posterior tibiofibular ligaments. The posterior tibiofibular ligament is particularly strong and projects over the back of the ankle joint

Question 5

Describe the medial and lateral projections of the tibia and fibula

Answer 5

The tibia projects medially downwards at the side of the ankle joint as the medial malleolus

The fibula projects downwards on the lateral side as the lateral malleolus

The lateral malleolus is at lower level than the medial malleolus and is slightly posterior to it

Question 6

What is the “mortise” into which the upper ankle bone fits?

Answer 6

The malleoli, the inferior surface of the tibia and the posterior tibiofibular ligament

Question 7

What are the bones of the ankle joint?

Answer 7

The talus sits at the summit. It is mounted on the upper surface of the heel bone or calcaneus. The talar surface fits into the ankle mortise forming the ankle joint. The articulation between the calcaneus and talus is the subtalar joint. Along the lateral edge of the foot, the calcaneus articulates with the cuboid through the calcaneocuboid joint. Tge medial edge of the foot is raised of the ground and this section is made up of four bones- the navicular (which articulates with the talus via the talonavicular joint) and the three cuneiforms (medial, intermediate and lateral)

Question 8

How is the longitudinal arch of the foot maintained?

Answer 8

The shape of the bones
Action of the small muscles
Strong ligaments and tendons e.g. the long and short plantar ligaments which span the arch. During running, the arch is compressed by about 1cm towards the ground, stretching the plantar ligaments which store energy like elastic as they are stretched and then recoil as the foot leaves the ground returning over 70% of their stored energy

Question 9

What are the four important synovial joints in the ankle region?

Answer 9

1. The ankle joint: between the talus and the mortise
2. The subtalar joint: between the talus and the calcaneus
3. The talonavicular joint: between the talus and the navicular
4. The calcaneocuboid joint between the calcanus and the cuboid

Question 10

What is the upper articular surface of the talus called?

Answer 10

The trochlea

Question 11

Describe the movements that take place at the subtalar joint

Answer 11

Abduction and eversion (movement of big toe away from the midline, causing the lateral edge of the foot to raise)

Adduction and inversion (movement of big toe towards the midline, causing the medial edge of the foot to raise)

Question 12

What type of joint is the talonavicular joint? What are the articular surfaces of this joint?

Answer 12

It is a ball and socket synovial joint

The “ball” is the head of the talus. The “socket” is formed from the sustentaculum tali and the navicular.

Question 13

What ligament lies between the sustentaculum tali and the navicular?

Answer 13

The spring ligament

Question 14

Describe the medial ligament of the ankle joint

Answer 14

The medial ligament is triangular in shape and is therefore sometimes called the deltoid ligament. Its apex is attached to the medial malleolus while its base attaches to the talus and also to the calcaneus via the sustentaculum tali. It therefore spans and strengthens the ankle joint and the subtalar joint. Anterior fibres of the deltoid ligament attach to the spring ligament and navicular, thus the socket of the talonavicular joint is also supported

Question 15

Describe the lateral ligament of the ankle joint

Answer 15

The lateral ligament is formed of three radiating fibrous bands. The anterior and posterior bands span the gap between the lateral malleolus and the anterior and posterior aspects of the lateral talar surface respectively, strengthening the lateral side of the ankle joint. The middle band passes downward to the calcaneus. It therefore spans both the ankle and subtalar joints and stabilises both these articulations

Question 16

What is the clinical significance of the lateral ligament of the ankle joint?

Answer 16

It is often sprained with injuries of the ankle

Question 17

What is the origin and insertion of the long plantar ligament? What joint does this ligament support?

Answer 17

Arises from the inferior surface of the calcaneus and extends under the surface of the cuboid and then inserts at the base of the metatarsals laterally. It supports the calcaneocuboid joint

Question 18

What nerve supplies the muscles on the front of the leg?

Answer 18

The common peroneal branch of the sciatic nerve

Question 19

What nerve supplies the muscles on the back of the leg?

Answer 19

The tibial branch of the sciatic nerve

Question 20

What centrally positioned muscles in the front of the leg are responsible for extension of the toes?

Answer 20

Extensor digitorum longus and extensor hallucis longus

Question 21

What structures hold down the tendons of the extensor digitorum longus and extensor hallucis longus as they pass over the front of the ankle?

Answer 21

The extensor retinacula. The superior extensor retinacular extends between the tibia and fibula. The inferior extensor retinacula is Y-shaped. The stem of the Y is attached to the lateral side of the calcaneus, The upper limb attaches to the medial malleolus. The lower limb sweeps round the medial border of the foot to blend with the deep fascia in the sole

Question 22

What is the origin of the extensor digitorum longus?

Answer 22

Fibular- upper 3/4 of the anterior surface and the intermusclar septum

Question 23

What is the insertion of the extensor digitorum longus?

Answer 23

As it approaches the ankle it gives rise to a tendon that passes deep to the extensor retinacula covered with a synovial sheath. The tendon divides into four slips which pass to the four lateral toes. Over the proximal phalanges these tendons form extensor expansions. A central slip thereafter gains insetion into the base of the middle phlanx and two collateral slips insert into the base of the distal phalanx.

Question 24

What is the supply of extensor digitorum longus?

Answer 24

The deep peroneal nerve

Question 25

What is the action of the extensor digitorum longus?

Answer 25

Extension of the interphalangeal and metatarsophalangeal joints of the four lateral toes

Question 26

What is the origin of extensor hallucis longus?

Answer 26

Mid-fibular shaft and interosseus membrane

Question 27

What is the insertion of extensor hallucis longus?

Answer 27

Base of the distal phalanx of the big toe

Question 28

What is the supply of extensor hallucis longus?

Answer 28

Deep peroneal nerve

Question 29

What additional muscle assists in extension of the toes?

Answer 29

Extensor digitorum brevis/hallucis brevis

Question 30

What is the origin of the extensor digitorum brevis/hallucis brevis?

Answer 30

Upper surface of the calcaneus

Question 31

What is the insertion of the extensor digitorum brevis/hallucis brevis?

Answer 31

Divides into four tendons. The most medial of these is the extensor hallucis brevis tendon which inserts into the proximal phalanx of the big toe. The lateral 3 tendons insert into the extensor expansion of the 2nd 3rd and 4th toes