Lower Limb: Muscles of the leg

Question 1

What are the 3 muscle compartments of the leg & the primary functions?

Answer 1

Anterior - dorsiflexion and extension of toes
Posterior - plantarflexion and flex toes
Lateral - evert the foot

Question 2

What muscles make up the anterior compartment of the leg?

Answer 2

From medial - lateral: Tibialis anterior, EHL, EDL & *Fibularis tertius

Question 3

What is the general common origin of the muscles of the anterior compartment of the leg?

Answer 3

The proximal, anterior aspect of the shafts of the tibia & fibula & adjacent IO membrane

Question 4

Insertion & function of tibialis anterior

Answer 4

Crosses in front of ankle joint to insert onto the medial aspect of the foot (medial cuneiform just before base of 1st metatarsal)

Dorsiflexion, inversion of foot* (instead of extension of toes) and supports medial arch of foot

Question 5

Insertion & function of EHL

Answer 5

Extensor hallicus longus inserts in to the base of the distal phalanx of the great toe
Dorsiflexion & extension of great toe

Question 6

Insertion & function of EDL

Answer 6

Splits into 4 tendons which each have 3 components
Lateral components insert into base of distal phalanx of toes (other than great toe)
Middle component inserts into middle phalanx of toes

Dorsiflexion and extension of toes

Question 7

Insertion & function of fibularis tertius

Answer 7

Small tendon which splits off from EDL
inserts into the base of the 5th metatarsal
Dorsiflexion and eversion*

Question 8

Which anterior compartment leg muscles allow movements other than dorsiflexion & extension of toes?

Answer 8

Tibialis anterior - inverts instead of extension of toes + supports medial arch

Fibularis tertius - everts foot instead of extending toes

Question 9

What is the extensor retinaculum and what passes beneath it?

Answer 9

Fibrous structure preventing bowstringing of extensor tendons
Located in front of the ankle joint

Passing beneath it from medial - lateral
‘Timothy has a nasty dirty toe’
Tibialias anterior, EHL, artery (anterior tibial), nerve (deep peroneal), EDL, Fibularis teritus

Question 10

What muscles are found in the lateral compartment of the leg?

Answer 10

Fibularis longus & brevis

Question 11

What is the course & function of fibularis longus?

Answer 11

Arises at proximal shaft of fibula and descends deep to brevis (once it arises more distally).
Tendon then runs with tendon of brevis laterally and behind lateral malleolus (held down by superior & inferior fibular retinacula)
Grooves calcaneus and cuboid bone and then turns to run under sole of foot to MEDIAL side of foot
Inserts into the base of 1st metatarsal

Eversion + Plantarflexion**

Question 12

What is the course & function of fibularis brevis?

Answer 12

Arises from lower aspect of shaft of fibula and is superficial to FL
Tendon runs with FL tendon laterally, passing behind lateral malleolus (held down by superior + inferior retinacula)
Grooves the calcaneus and cuboid bones and inserts LATERALLY at the base of the 5th metatarsal

Eversion

Question 13

What are the DEEP muscles of the posterior compartment of the legs?

Answer 13

From medial - lateral at origin:
FDL
Tibialis posterior
FHL

Question 14

What is the common origin of the deep muscles of the posterior compartment of the leg?

Answer 14

Arise from the shaft of the tibia or fibula and the adjacent IO membrane

FDL + TP from tibia
FHL from fibula

Question 15

What is the common course of FDL, TP and FHL at the foot?

Answer 15

All tendons pass between the medial malleolus and the calcaneus and pass onto the plantar surface of the foot

Question 16

What is the flexor retinaculum of the foot and what structures pass beneath it?

Answer 16

Holds the deep posterior muscles of the legs as the tendons pass between the medial malleolus and the calcaneus

Structures passing from medial malleolus to calcaneus:
‘Tom, dick and very naughty harry’
Tibialis posterior, FDL, artery (posterior tibial), vein (posterior tibial), nerve (tibial) and FHL

Question 17

What is the insertion & function of tibialis posterior?

Answer 17

Inserts into the medial cuneiform bone WITH TA
Plantar flexion
*Inverts foot when contracts with TA
Supports medial arch with TA

Question 18

What is the insertion & function of FHL?

Answer 18

Inserts on to base of distal phalanx of great toe (plantar aspect)
Flexes great toe

Question 19

What is the insertion & function of FDL?

Answer 19

Crosses over FHL as it passes onto the plantar surface of foot, splits into 4 tendons and inserts into the distal phalanx of lateral 4 toes
Flexes lateral 4 toes

Question 20

What are the SUPERFICIAL muscles of the posterior compartment of the leg?

Answer 20

From superficial to deep:
Gastrocnemius, plantaris, soleus, popliteus*

GPS P*

Question 21

Origin, insertion & function of popliteus

Answer 21

Lateral aspect of the lateral condyle (femur) & lateral meniscus and inserts into tibia above soleal line

Active contraction unlocks knee

Question 22

Origin, insertion & function of Gastrocnemius

Answer 22

2 bellies arising from each condyl of the femur and insert via common achilles tendon into the posterior aspect of calcaneus

Plantarflexion and flexion of knee

Question 23

Origin, insertion & function of Plantaris

Answer 23

Origin on femur (relationship to head of gastrocnemius) and inserts via achilles tendon into calcaneus
Regressive muscle
Plantar flexion + flexion of knee

Question 24

Origin, insertion & function of soleus

Answer 24

Long oblique origin with a fibrous arch that allows passage of structures
inserts via achilles tendon into calcaneus
Plantar flexion only

Question 25

What is the main function of the deep posterior leg muscles?

Answer 25

Plantar flexion (TA) and flexion of toes (FDL, FHL)

Question 26

What muscles are important for inversion of the foot?

Answer 26

Simultaneous contraction of TA and TP

Question 27

What is the main function of the superficial posterior leg muscles?

Answer 27

Plantar flexion (all) and flexion at knee (gastrocenemius and plantaris)