Anterior leg

Question 1

Anterior compartment of the leg

Answer 1

4 muscles:
-Tibilais anterior

• Extensor hallicus longus
• Extensor digitorum longus

Fibularis tertius

The anterior (extensor) compartment lies between the deep fascia and the interosseous membrane between the tibia and fibula. The muscles in this compartment are ankle extensors or dorsiflexors.

All these muscles are supplied by the deep branch of the common fibular nerve. The toe extensors and ankle dorsiflexors help the foot to clear the ground in walking. There are two extensor retinacula which span the bones to prevent bowstringing of the tendons

Question 2

Tibialis anterior

Answer 2

Arises from the upper part of the lateral tibial surface and the interosseous membrane, and inserts into the medial cuneiform and the first metatarsal

Produces both dorsiflexion and inversion (inversion at subtalar joint)

Question 3

Extensor hallicus longus

Answer 3

Arises from the medial part of the anterior surface of the fibula and the interosseous membrane, and inserts into the base of the distal phalanx of the great toe

Its actions are extension of the hallux (great toe) and weak dorsiflexion at the ankle

Question 4

Extensor digitorum longus

Answer 4

arises from the upper two-thirds of the anterior surface of the fibula and the interosseous membrane, and inserts by four tendons into the bases of the middle and distal phalanges of the four lesser toes, as in the fingers.

Its actions are extension of the toes and weak dorsiflexion at the ankle

Question 5

Fibularis tertius

Answer 5

Arises in continuity with extensor digitorum longus but inserts into the dorsal surface of the base of the fifth metatarsal.

Dorsiflexes the ankle and everts the foot

Question 6

What is eversion?

Answer 6

The sole of the foot faces outwards, and the lateral border moves outwards and upwards

occurs at the subtalar joint

Question 7

Lateral compartment of the leg

Answer 7

The lateral (evertor) compartment of the leg is bounded by the anterior and posterior intermuscular septa.

The muscles in this compartment produce eversion of the foot at the subtalar joint. However, as their tendons run behind the lateral malleolus and hence posterior to the axis of the ankle joint, they are also weak ankle flexors or plantarflexors

Question 8

Muscles in lateral compartment of leg

Answer 8

Fibularis longus

Fibularis brevis

Question 9

Fibularis longus

Answer 9

Arises from the upper part of the lateral aspect of the fibular shaft. Its tendon passes behind the lateral malleolus, grooves the cuboid to cross the sole obliquely, and inserts into the medial cuneiform and the base of the first metatarsal.

It is the antagonist to tibialis anterior. It also supports the lateral longitudinal and transverse arches of the foot

Question 10

Fibularis brevis

Answer 10

Arises from the lower part of the lateral aspect of the fibular shaft distal to the origin of fibularis longus. Its tendon also runs behind the lateral malleolus, but lies closer to the bone than that of longus. It inserts into the tuberosity at the base of the fifth metatarsal