Lecture 13: Anterior and Posterior Leg

Question 1

What are the bones of the lower leg and what holds them together?

Answer 1

Tibia and fibula

Held together by interosseous membrane

Question 2

What important anatomical structures are included in the superficial fascia of the leg?

Answer 2

Saphenous veins = great saphenous v. and lesser saphenous v.

Question 3

Where do the saphenous veins arise from?

Answer 3

Dorsal venous plexus of the foot

Question 4

Describe the path of the great saphenous v. as it arises from the dorsal venous plexus of the foot

Answer 4

Ascends anteriorly to the medial malleolus, up the medial leg, becomes a tributary to the femoral v. in the femoral triangle

Question 5

Describe the path of the lesser saphenous v. as it arises from the dorsal venous plexus of the foot

Answer 5

Ascends posteriorly to the lateral malleolus and then continues on the back of the leg to become a tributary to the popliteal v.

Question 6

What 5 nerves provide cutaneous innervation to the lower leg?

Answer 6

Posterior femoral cutaneous n.
Saphenous n.
Superficial peroneal n.
Lateral sural cutaneous n.
Medial sural cutaneous n.

Question 7

What is the deep investing fascia of the leg?

Answer 7

Crural fascia

Question 8

Where does the crural fascia attach to the leg?

Answer 8

Anterior and medial borders of the tibia

2 intermuscular septa also extend from the crural fascia to the fibula (anterior + posterior)

Question 9

What divides the lower leg into 3 compartments?

Answer 9

Interosseous membrane + 2 intermuscular septa formed by crural fascia

Question 10

In general, what action is performed by the contents of the anterior compartment of the leg?

Answer 10

Anterior compartment contains the dorsiflexors of the ankle

Question 11

What innervates all muscles of the anterior compartment of the leg, and what is this a terminal branch of?

Answer 11

All muscles are innervated by the deep peroneal n., which is a terminal branch of the common peroneal n.

Question 12

What is the blood supply to the anterior compartment of the leg, and what is this a terminal branch of?

Answer 12

Anterior tibial a., which is a terminal branch of the popliteal a.

Question 13

What are the muscular contents of the anterior compartment of the leg?

Answer 13

Tibialis anterior m.
Extensor digitorum longus m.
Peroneus tertius m.
Extensor hallucis longus m.

Question 14

Origin of tibialis anterior

Answer 14

Upper 2/3 of lateral shaft of tibia + interosseus membrane

Question 15

Insertion of tibialis anterior

Answer 15

Medial side of medial (1st) cuneiform + base of 1st metatarsal

Question 16

Action of tibialis anterior

Answer 16

Dorsiflexion and inversion of foot

Question 17

Origin of extensor digitorum longus

Answer 17

Anterior surface of fibula + interosseus membrane

Question 18

Insertion of extensor digitorum longus

Answer 18

Middle and distal phalanges of toes 2-5 (by way of dorsal expansions)

Question 19

Action of extensor digitorum longus

Answer 19

Extension of toes, dorsiflexion and eversion of foot

Question 20

Origin of peroneus tertius

Answer 20

Distal fibula + interosseus membrane

Question 21

Insertion of peroneus tertius

Answer 21

Base of 5th metatarsal

Question 22

Action of peroneus tertius

Answer 22

Dorsiflexion and eversion of foot

Question 23

Origin of extensor hallucis longus

Answer 23

Middle of 1/2 of anterior fibula + interosseus membrane

Question 24

Insertion of extensor hallucis longus

Answer 24

Base of distal phalanx of big toe

Question 25

Action of extensor hallucis longus

Answer 25

Extension of big toe, dorsiflexion of foot

Question 26

Origin/insertion/action: Tibialis anterior m.

Answer 26

Origin: upper 2/3 of lateral shaft of tibia + interosseus membrane Insertion: medial side of medial (1st) cuneiform + base of 1st metatarsal Action: dorsiflexion and inversion of foot

Question 27

Origin/insertion/action: Extensor digitorum longus m.

Answer 27

Origin: anterior surface of fibula + interosseus membrane Insertion: middle and distal phalanges of toes 2-5 (by way of dorsal expansion) Action: extension of toes, dorsiflexion and eversion of foot

Question 28

Origin/insertion/action: Peroneus tertius m.

Answer 28

Origin: distal fibula + interosseus membrane Insertion: base of 5th metatarsal Action: dorsiflexion and eversion of foot

Question 29

Origin/insertion/action: Extensor hallucis longus m.

Answer 29

Origin: middle of 1/2 of anterior fibula + interosseus membrane Insertion: base of distal phalanx of big toe Action: extension of big toe, dorsiflexion of foot

Question 30

What compartment of the leg contains 2 muscles that serve to evert the foot?

Answer 30

Lateral compartment

Question 31

What supplies innervation to the lateral compartment of the leg and what is this a terminal branch of?

Answer 31

Superficial peroneal n., which is a terminal branch of the common peroneal n.

Question 32

What is the blood supply to the lateral compartment of the leg, and what does this branch off of?

Answer 32

Fibular circumflex aa. = branches of peroneal a.

Question 33

What are the muscular contents of the lateral compartment of the leg?

Answer 33

Peroneus longus m. | Peroneus brevis m.

Question 34

Origin of peroneus longus

Answer 34

Lateral shaft of head of fibula

Question 35

Insertion of peroneus longus

Answer 35

Medial (1st) cuneiform + base of 5th metatarsal

Question 36

Action of peroneus longus m.

Answer 36

Plantar flexion and eversion of foot, supports arch of foot

Question 37

Origin of peroneus brevis

Answer 37

Lateral shaft of fibula

Question 38

Insertion of peroneus brevis

Answer 38

Base of 5th metatarsal

Question 39

Action of peroneus brevis

Answer 39

Plantar flexion of foot

Question 40

Origin/insertion/action: Peroneus longus m.

Answer 40

Origin: lateral shaft of head of fibula Insertion: medial (1st) cuneiform + base of 5th metatarsal Action: plantar flexion and eversion of foot; supports arch of foot

Question 41

Origin/insertion/action: Peroneus brevis m.

Answer 41

Origin: lateral shaft of fibula Insertion: base of 5th metatarsal Action: plantar flexion of foot

Question 42

What provides innervation to the posterior compartment of the leg?

Answer 42

Tibial n.

Question 43

What muscles are present in the posterior compartment of the leg?

Answer 43

``` Gastrocnemius (lateral + medial heads) Soleus Plantaris Popliteus Flexor hallucis longus Flexor digitorum longus Tibialis posterior ```

Question 44

Origin of gastrocnemius

Answer 44

Just superior to lateral+medial epicondyles of femur

Question 45

Insertion of gastrocnemius

Answer 45

Middle of posterior surface of calcaneus

Question 46

Action of gastrocnemius

Answer 46

Flexion of leg, plantar flexion of foot

Question 47

Origin of soleus

Answer 47

Upper posterior surface of fibula

Question 48

Insertion of soleus

Answer 48

Middle of posterior surface of calcaneus (same as gastroc)

Question 49

Action of soleus

Answer 49

Plantar flexion of foot

Question 50

Origin of plantaris

Answer 50

Lower lateral supracondylar line + popliteal surface of femur

Question 51

Insertion of plantaris

Answer 51

Calcaneus tendon

Question 52

Action of plantaris

Answer 52

Insignificant/unknown

Question 53

Origin of popliteus

Answer 53

Tendon just inferior to lateral epicondyle of femur

Question 54

Insertion of popliteus

Answer 54

Posterior tibia above popliteal line

Question 55

Action of popliteus

Answer 55

Flexion of leg, rotation of tibia medially

Question 56

Origin of flexor hallucis longus

Answer 56

Lower 2/3 of posterior fibula + interosseus membrane

Question 57

Insertion of flexor hallucis longus

Answer 57

Base of distal phalanx of big toe

Question 58

Action of flexor hallucis longus

Answer 58

Flexion of distal phalanx of big toe

Question 59

Origin of flexor digitorum longus

Answer 59

Posterior surface of tibia below popliteal line

Question 60

Insertion of flexor digitorum longus

Answer 60

Plantar surface of base of distal phalanges of toes 2-5

Question 61

Action of flexor digitorum longus

Answer 61

Flexion of distal phalanges of toes 2-5

Question 62

Origin of tibialis posterior

Answer 62

Interosseous membrane and posterior shaft of tibia+fibula

Question 63

Insertion of tibialis posterior

Answer 63

Tuberosity of navicular, cuboid, 3 cuneiforms, + bases of 2-4th metatarsals

Question 64

Action of tibialis posterior

Answer 64

Inversion of foot; assists in plantar flexion

Question 65

Origin/insertion/action: Gastrocnemius m.

Answer 65

Origin: superior to epicondyles of femur Insertion: calcaneus Action: leg flexion, foot plantar flexion

Question 66

Origin/insertion/action: Soleus m.

Answer 66

Origin: upper posterior fibula Insertion: calcaneus Action: plantar flexion of foot

Question 67

Origin/insertion/action: Plantaris m.

Answer 67

Origin: lateral supracondylar line + popliteal surface of femur Insertion: calcaneus tendon Action: insignificant

Question 68

Origin/insertion/action: Popliteus m.

Answer 68

Origin: tendon just inferior to lateral epicondyle of femur Insertion: posterior tibia above popliteal line Action: flexion of leg, rotation of tibia medially

Question 69

Origin/insertion/action: Flexor hallucis longus m.

Answer 69

Origin: posterior tibia below popliteal line Insertion: plantar surface of base of distal phalanges of toes 2-5 Action: flexion of distal phalanges of toes 2-5

Question 70

Origin/insertion/action: Tibialis posterior m.

Answer 70

Origin: interosseous membrane and posterior shaft of tibia+fibula Insertion: tuberosity of navicular, cuboid, 3 cuneiforms, and bases of 2-4 metatarsals Action: inversion of foot, assists in plantar flexion