Leg, Ankle and Foot (Week 5--Miller)

Question 1

Bones of the foot

Answer 1

Phalanges (14)

Metatarsus (5)

Tarsus (7–3 proximal and 4 distal)

Question 2

7 tarsal bones

Answer 2

3 proximal: calcaneus, talus, navicular

4 distal: 3 cuneiform, cuboid

Question 3

Joints of the foot

Answer 3

Interphalangeal (IP) joints

Metatarsophalangeal (MTP) joints

Tarsometatarsal (TM) joints

Intertarsal joints

Midtarsal joints

Question 4

Anterior compartment of the leg

Answer 4

Extensor (dorsiflexor) compartment

4 muscles: tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus tertius muscle tendon (very small!)

Deep peroneal nerve

Anterior tibial artery

Question 5

Lateral compartment of the leg

Answer 5

2 muscles: peroneus (fibularis) longus, peroneus (fibularis) brevis

Superficial peroneal nerve

NO ARTERY (just branches from fibular artery of posterior compartment and other arteries)

Question 6

Common peroneal nerve

Answer 6

Not in the lateral compartment

However, wraps around neck of fibula posteriorly and is easily lacerated

2 branches are deep and superficial peroneal nerves so injury to common peroneal nerve can lead to loss of dorsiflexion (anterior compartment of leg) and eversion (lateral compartment of leg)

(loss of dorsiflexion results in foot drop during walking)

Question 7

Superficial peroneal (fibular) nerve

Answer 7

Branch of common peroneal nerve

Lies deep to peroneus longus muscle and innervates both muscles of lateral compartment, thus controls eversion of the foot

After it innervates muscles of lateral compartment, becomes cutaneous (sensory) nerve

Question 8

Posterior compartment of the leg

Answer 8

Flexor compartment

Deep layer muscles: popliteus, flexor hallucis longus, tibialis posterior

Superficial layer muscles: gastrocnemius, soleus, plantaris

Tibial nerve

Posterior tibial artery and fibular artery (looks like it was heading to lateral compartment but didn’t quite make it there!)

Question 9

Superficial veins

Answer 9

Great and small saphenous veins

Are not subjected to forces from arteries and muscles forcing blood up the limb

Valves in perforating veins must prevent high pressure blood in deep veins from moving into superficial veins

When muscles within compartments relax, blood sucked from superficial into deep veins to be sent up to heart

Question 10

Deep veins

Answer 10

Veins within compartments

Subjected to intermittent pressure from adjacent arteries and muscular action which forces blood up the limb

Question 11

Sural nerve

Answer 11

Cutaneous (sensory) nerve

Made from tibial nerve after it is joined by branch from common fibular peroneal nerve (communicating sural)

Emerges from popliteal fossa in groove between heads of gastrocmenius

Accompanies small saphenous vein and supplies posterior leg

Question 12

Crural fascia

Answer 12

Continuation of fascia lata in the leg

Question 13

Posterior compartment of the leg superficial layer

Answer 13

Gastrocnemius

Soleus

Plantaris tendon

Question 14

Neurovascular structures between superficial and deep layers of posterior compartment of leg

Answer 14

Posterior tibial artery (branch of popliteal artery)

Fibular artery (branch of posterior tibial artery)

Tibial nerve (branch of sciatic nerve)

Question 15

Posterior compartment of the leg deep layer

Answer 15

Popliteus

Tibialis posterior

Flexor digitorum longus

Flexor hallucis longus

Question 16

Calcaneal tendon (achilles tendon)

Answer 16

Common tendon of superficial layer muscles (gastrocnemius, soleus, plantaris)

Inserts onto calcaneus bone

Question 17

Ankle (talocrural) joint

Answer 17

Synovial joint (hinge-type)

Between distal tibia/fibula and superior part of talus

Main movements are dorsiflexion and plantar flexion

Joint capsule is reinforced laterally by lateral ligament and medially by deltoid (medial) ligament

Question 18

3 ligaments of the lateral ligament

Answer 18

Anterior talofibular ligament

Posterior talofibular ligament

Calcaneofibular ligament

Note: lateral ligament resists inversion of the foot

Question 19

Lateral ankle sprain

Answer 19

Usually caused by excessive inversion of the foot with plantar flexion of the ankle

Anterior talofibular ligament and calcaneofibular ligament partially torn (leads to pain and local swelling)

In typical lateral ankle sprain, USUALLY anterior talofibular ligament is involved

Question 20

Deltoid (medial) ligament

Answer 20

Triangular in shape

Attaches superiorly to medial malleolus and inferiorly separates into 4 parts which attach to talus, calcaneus and navicular bones

Note: deltoid (medial) ligament resists eversion of the foot

Question 21

Medial ankle sprain

Answer 21

Less common than lateral ankle sprain

Caused by excessive eversion

Because deltoid (medial) ligament so strong, usually causes deltoid ligament to pull off the tip of the medial malleolus (ouch…!)

Question 22

Nerves of the leg (big picture)

Answer 22

Sciatic nerve branches into common peroneal and tibial divisions near popliteal fossa

Tibial nerve crosses knee posterior and enters posterior compartment of leg (tibial then turns into medial and lateral plantar nerves)

Common peroneal nerve wraps around lateral side of leg near neck of fibula then divides into superficial peroneal (fibular) nerve and deep peroneal (fibular) nerve; also gives off lateral cutaneous nerve

Superficial peroneal nerve dives deep to peroneus (fibularis) longus and becomes nerve of the lateral compartment

Deep peroneal nerve enters and becomes nerve of anterior compartment

Question 23

Arteries of the leg (big picture)

Answer 23

External iliac artery turns into femoral which gives off deep femoral artery, then goes through adductor hiatus to become popliteal artery

Popliteal artery divides into anterior and posterior tibial artery at lower border of popliteus muscle

Anterior tibial artery pierces interosseus membrane to enter and become artery of anterior compartment, then crosses the ankle and is called dorsalis pedis artery, which then turns into arcuate artery

Posterior tibial artery continues inferiorly in posterior compartment and gives rise to fibular artery then continues to becomes medial and lateral plantar arteries

Posterior tibial artery terminates distal to flexor retinaculum by dividing into medial and lateral plantar arteries that supply muscles on the sole of the foot

Question 24

Structures related posteriorly to medial malleolus

Answer 24

“Tom, Dick, ANd Harry”

Tibialis posterior tendon

Flexor Digitorum longus tendon

Posterior tibial Artery

Tibial Nerve

Flexor Hallucis longus tendon

Question 25

Flexor retinaculum

Answer 25

Roof of tarsal tunnel (on medial malleolus)

Question 26

Structures related posteriorly to lateral malleolus

Answer 26

Peroneus (fibularis) longus tendon

Peroneus (fibularis) brevis tendon

Question 27

All the retinaculums of the foot

Answer 27

Superior extensor retinaculum (anterior compartment tendons)

Inferior extensor retinaculum (anterior compartment tendons)

Fibular retinaculum (lateral compartment tendons)

Flexor retinaculum (posterior compartment tendons)

Question 28

Dorsum of the foot

Answer 28

Dorsal venous arch gives rise to great saphenous vein medially and small saphenous vein laterally

Superior and inferior extensor retinaculae bind down the extensor hallucis longus and extensor digitorum longus tendons

Dorsalis pedis artery gives rise to arcuate artery which arcs across base of metatarsal bones and gives rise to 2nd-4th dorsal metatarsal arteries (1st dorsal metatarsal artery arises directly from dorsalis pedis artery and gives rise to deep plantar artery which joins arterial arch on plantar surface of foot) and those give rise to dorsal digital arteries

2 intrinsic foot muscles: extensor hallucis brevis and extensor digitorum brevis

Question 29

Swelling of which two foot muscles can be mistaken for ankle problem?

Answer 29

Extensor digitorum brevis and extensor hallucis brevis

(on dorsum of foot)

Question 30

Plantar foot

Answer 30

Longitudinal arch and transverse arch

Plantar aponeurosis

Long plantar ligament, spring ligament, peroneus longus tendon, posterior tibialis tendon

Thenar, hypothenar, central and deep compartments

Lateral and medial plantar nerves

Lateral and medial plantar arteries

Question 31

Plantar foot arches

Answer 31

Longitudinal arch: lateral and medial arches

Transverse arch

Arches act as shock absorbers for supporting weight of body and propelling it during movement

Question 32

Plantar foot arch abnormalities

Answer 32

Pes planus (flat foot): longitudinal arch depressed or collapsed; congenital or acquired

Pes cavus (claw foot): medial longitudinal arch unduly high; most cases caused by muscle imbalance (results from poliomyelitis)

Question 33

Which ligaments/tendons help support which arches?

Answer 33

Peroneus longus tendon helps maintain transverse arch

Long plantar ligament and spring ligament help maintain longitudinal arch

Question 34

4 factors that maintenance of arches of the foot depend on

Answer 34

1) Shape of interlocking bones
2) Strength of ligaments
3) Plantar aponeurosis
4) Action of muscles through bracing action of their tendons

Question 35

Plantar aponeurosis

Answer 35

Helps support arches of foot and protects deeper structures

Plantar digital nerves (cutaneous branches of lateral and medial plantar nerves) run deep to superficial transverse metatarsal ligament which is continuous with plantar aponeurosis

Question 36

Central compartment of plantar foot superficial layer

Answer 36

Flexor digitorum brevis

Question 37

Muscles of the foot innervation

Answer 37

Medial plantar nerve

Lateral plantar nerve

Both are branches of the tibial nerve, both course with their respective arteries

In central compartment

Send deep branches which course between central and deep compartment

Question 38

Blood supply to plantar foot

Answer 38

Posterior tibial artery branches into medial and lateral plantar arteries

(Don’t have to know: which pass into space between central and deep compartments to form plantar arch (which anastomoses with deep plantar branch of dorsalis pedis artery))

Question 39

Where do cutaneous nerves of lower limb come from?

Answer 39

Branches of:

Femoral nerve

Obturator nerve

Tibial nerve

Common peroneal nerve

Direct branches of lumbar plexus or sacral plexus

Question 40

Cutaneous innervation of the thigh

Answer 40

Anterior thigh is innervated by branches of the femoral nerve (L2-4)

**Posterior** thigh is innervated by **posterior femoral cutaneous nerve**

Lateral thigh is innervated by lateral femoral cutaneous nerve (L2-3)

Medial thigh is innervated by obturator nerve (L2-4)