[Anatomy] Leg And Foot

Front 1

crural fascia

Back 1

▪ (deep fascia of the leg) is continuous with fascia lata of the thigh
▪ gives rise to anterior, posterior and transverse intermuscular septa
▪ The interosseous membrane and anterior and posterior intermuscular septa form 3 compartments: anterior, lateral, and posterior
▪ The transverse intermuscular septum separates muscles of the posterior compartment into a superficial and deep group

Front 2

compartment syndrome

Back 2

Swelling within a compartment can compromise blood flow and/or innervation to tissues within that space

Front 3

retinacula

Back 3

crural fascia thickens distally to form the flexor, extensor, and fibular retinacula, which hold tendons in place as they course into the foot

Front 4

tendon sheaths

Back 4

As tendons pass under a retinaculum, they are protected by synovial tendon sheaths (facilitate sliding by reducing friction; can become infected/inflamed, causing pain)

Front 5

posterior compartment of leg (actions, innervation)

Back 5

flex knee joint
plantarflex ankle joint (towards ground)
invert foot (sole faces medially)
flex toes (towards ground)
innervation: tibial nerve

Front 6

superficial group of leg

Back 6

innervation: tibial nerve
insertion: calcaneal tuberosity via calcaneal (Achilles) tendon

gastrocnemius, soleus, plantaris

Front 7

deep group of leg

Back 7

innervation: tibial nerve
popliteus, flexor digotorum longus, flexor hallicus longus, tibialist posterior

Front 8

tibial nerve

Back 8

o Medial branch of the sciatic nerve
o Travels between the superficial and deep muscle groups of the posterior compartment
o Innervates the muscles of the posterior compartment of the leg
o Innervates skin on posterolateral aspect of leg and lateral foot (via sural nerve)
o Eventually courses posterior to medial malleolus to enter the foot, where it divides into medial and lateral plantar nerves

Front 9

gastrocnemius

Back 9

part of superficial group

(medial and lateral head)
Origin: distal femur (proximal to the femoral condyles)
Actions: flex knee joint and plantarflex ankle joint

Front 10

calcaneal tendon reflex

Back 10

tests the S1 spinal level

Front 11

triceps surae

Back 11

part of superficial group; Gastrocnemius + soleus

Front 12

soleus

Back 12

part of superficial group

Origin: fibular head and shaft, tibial shaft
Action: plantarflex ankle joint

Front 13

plantaris

Back 13

part of superficial group

(small muscle belly with a long, thin tendon)
Origin: distal femur
Actions: weakly flex knee joint and plantarflex ankle joint
Note: absent in 5-10% of people

Front 14

popliteus

Back 14

part of deep group
Origin: distal femur
Insertion: proximal tibia
Action: unlocks the knee from extended position (when knee is extended in standing position, popliteus rotates the femur laterally 5 degrees on the tibia, unlocking the knee so that flexion can occur)

Front 15

flexor digitorum longus

Back 15

part of deep group
Origin: tibial shaft
Insertion: tendon travels posterior to medial malleolus of tibia, divides into four tendons to insert on distal phalanges of digits 2-5
Actions: flex digits 2-5; plantarflex ankle joint

Front 16

flexor hallucis longus

Back 16

part of deep group
Origin: fibular shaft & interosseous membrane
Insertion: tendon travels posterior to medial malleolus of tibia and inserts on distal phalanx of hallux
Actions: flex hallux; weakly plantarflex ankle joint

Front 17

tibialis posterior

Back 17

part of deep group
Origin: interosseous membrane, fibular & tibial shafts
Insertion: tendon travels posterior to medial malleolus of tibia and inserts primarily on the navicular tuberosity
Actions: plantarflex ankle joint; invert foot

Front 18

flexor retinaculum

Back 18

Tendons of flexor digitorum longus, flexor hallucis longus, and tibialis posterior are held in place at the ankle by the flexor retinaculum

Front 19

Tom, Dick aNd Harry

Back 19

helps summarize the relative position (anterior, middle, & posterior) of the tendons of tibialis posterior, flexor digitorum longus, tibial artery, tibial nerve, and flexor hallucis longus as they travel posterior to the medial malleolus

Front 20

plantar foot - skin

Back 20

skin on the sole of the foot is very thick (especially at weight-bearing parts of the foot like the heel, lateral margin, and base of the hallux)

Front 21

plantar foot - superficial fascia

Back 21

has fibrous septa dividing the tissue into fat-filled areas for shock absorption (especially prominent calcaneal fat pad); the fibrous septa also anchor the skin to the deep fascia (improves grip)

Front 22

plantar fascia

Back 22

o Deep fascia of the sole
o The thickened central portion is called the plantar aponeurosis Functions: protection, maintaining arches/integrity of foot

Front 23

plantar fasciitis (where is the pain?)

Back 23

Inflammation of the plantar aponeurosis presents as pain on the plantar surface of the heel and medial aspect of foot; it can induce ossification in the posterior attachment of the aponeurosis, forming a calcaneal spur; a bursa may develop at the spur and this may also become inflamed

Front 24

medial plantar nerve

Back 24

Tibial n. divides into medial and lateral plantar nerves as it enters sole
• Motor: Innervates abductor hallucis, flexor hallucis brevis, 1st (medial) lumbrical, and flexor digitorum brevis
• Sensory: Innervates medial aspect of sole & tips and plantar aspects of medial 3 ½ digits

Front 25

lateral plantar nerve

Back 25

Tibial n. divides into medial and lateral plantar nerves as it enters sole
• Motor: Innervates abductor digiti minimi, flexor digiti minimi, quadratus plantae, adductor hallucis, 2nd-4th lumbricals, all interossei
• Sensory: Innervates lateral aspect of sole & tips and plantar aspects of lateral 1 ½ digits

Front 26

layer 1 of plantar foot

Back 26

contains abductor hallucis, abductor digiti minimi, flexor digitorum brevis

Front 27

abductor hallucis

Back 27

part of layer 1
Actions: abduct and flex hallux (MTP joint)
Innervation: medial plantar n.

Front 28

abductor digiti minimi

Back 28

part of layer 1
Actions: abduct and flex digit 5 (MTP joint)
Innervation: lateral plantar n.

Front 29

flexor digitorum brevis

Back 29

layer 1
Insertion: 4 tendons; divide to insert on middle phalanges of digits 2-5
Action: flex digits 2-5 (MTP & PIP joints)
Innervation: medial plantar n.

Front 30

layer 2 of plantar foot

Back 30

tendon of flexor hallucis longus, tendon of flexor digitorum longus, quadratus plantae, lumbricals

Front 31

tendon of flexor hallucis longus

Back 31

Runs deep to FDL tendon and along the medial side of the plantar foot. Sends tendinous slip(s) to the tendon of FDL. Travels between the two sesamoids of the hallux, to insert on the distal phalanx. Flexes the MTP & IP joint of the hallux.

Front 32

tendon of flexor digitorum longus

Back 32

Crosses superficial to FHL tendon and splits into 4 tendons (to digits 2-5). Each tendon passes through the divided tendon of flexor digitorum brevis to insert on the distal phalanx. Flexes the MTP, PIP & DIP joints of digits 2-5.

Front 33

quadratus plantae

Back 33

layer 2
Insertion: tendon of flexor digitorum longus
Action: assist flexor digitorum longus in flexing digits 2-5
Innervation: lateral plantar n.

Front 34

lumbricals

Back 34

layer 2
Origin: tendons of flexor digitorum longus
Insertion: extensor expansions of digits 2-5 (see note below)
Actions: flex MTP joints; extend PIP & DIP joints of digits 2-5
Innervation: Medial (1st) lumbrical (medial plantar n.); Lateral 3 lumbricals (lateral plantar n.)

Front 35

extensor expansions

Back 35

The tendons of extensor digitorum longus and extensor hallucis longus form broad extensor expansions over the dorsal surface of the phalanges

Front 36

layer 3 of plantar foot

Back 36

flexor hallucis brevis
adductor hallucis (transverse & oblique heads)
flexor digiti minimi brevis

Front 37

flexor hallucis brevis

Back 37

Insertion: two tendons insert on proximal phalanx of hallux
Action: flex hallux (MTP joint)
Innervation: medial plantar n.

*Each tendon (medial & lateral) has a sesamoid embedded in it. These sesamoids provide added leverage, help hold the tendon of FHL in place, & protect the tendon of FHL from fraying/pressure during toe-off

Front 38

adductor hallucis (transverse & oblique heads)

Back 38

layer 3
Action: adduct hallux (MTP joint)
Innervation: lateral plantar n.

Front 39

flexor digiti minimi brevis

Back 39

layer 3
Action: flex digit 5 (MTP joint)
Innervation: lateral plantar n.

Front 40

layer 4 of plantar foot (deep)

Back 40

interossei
(all innervated by lateral plantar n.)
3 Plantar Interossei
Action: adduct (“PAD”) MTP joints of digits 3-5

4 Dorsal Interossei
Action: abduct (“DAB”) MTP joints of digits 2-4

Front 41

arteries of posterior leg and plantar foot

Back 41

Femoral artery passes through adductor hiatus and becomes the popliteal artery, which branches into multiple arteries

Front 42

branches of popliteal artery

Back 42

genicular branches
anterior tibial artery
posterior tibial artery (medial and lateral plantar arteries)

Front 43

genicular branches

Back 43

(genu = knee), branches of popliteal artery; form anastomoses around knee joint

Front 44

anterior tibial artery

Back 44

• branch of popliteal artery; supplies anterior compartment / anterolateral leg
• Passes through gap in superior part of the interosseous membrane
• descends along the membrane with the deep fibular nerve
• terminates at ankle, where it becomes dorsalis pedis

Front 45

posterior tibial artery

Back 45

• Travels with tibial nerve, between superficial & deep muscle groups
• Supplies posterior leg
• Gives off fibular artery, which supplies posterolateral leg
• Around the ankle, the posterior tibial artery gives off medial malleolar and calcaneal branches
travels posterior to medial malleolus, between tendons of FDL and FHL, deep to flexor retinaculum
• Divides into medial and lateral plantar arteries in the sole

Front 46

medial plantar artery

Back 46

branches from posterior tibial artery at the sole; anastomoses with lateral plantar artery

+ Travels with medial plantar nerve
+ Gives rise to superficial plantar arch (superficial to flexor digitorum brevis)
+ Gives rise to plantar digital arteries to hallux and medial side of digit 2 (anastomose with branches from the lateral plantar artery)
+ Supplies superficial tissues of sole and muscles associated with the hallux

Front 47

lateral plantar artery

Back 47

branches from posterior tibial artery at the sole; anastomoses with medial artery

+ Travels with lateral plantar nerve
+ Supplies most of the plantar foot
+ Gives rise to deep plantar arch (between 3rd & 4th plantar layers)
+ Deep plantar arch gives rise to plantar metatarsal arteries
+ Plantar metatarsal arteries give rise to plantar digital arteries to the medial and lateral aspects of the digits (anastomose with branches from medial plantar artery)

Front 48

veins of posterior leg and plantar foot

Back 48

Deep veins accompany the arteries and share the same names ; popliteal is main vein

Front 49

popliteal vein

Back 49

- formed by junction of anterior and posterior tibial veins, which drain the deep tissues of the leg
- Popliteal vein also receives the small saphenous vein (draining superficial tissues)
- Popliteal vein ends at adductor hiatus, where it becomes the femoral vein

Front 50

nerves of anterior and lateral leg

Back 50

common fibular (peroneal) nerve (superficial and deep)

Front 51

common fibular (peroneal) nerve

Back 51

o Lateral branch of the sciatic nerve
o Winds around the neck of the fibula (it is susceptible to injury here)
o Contributes branch to the sural nerve, which innervates the skin of the posterolateral leg and lateral border of the foot (the tibial nerve also contributes to the sural nerve)
o Two terminal branches
• Superficial and deep fibular (peroneal) nerves

Front 52

superficial fibular (peroneal ) nerve

Back 52

• Innervates the muscles of the lateral compartment of the leg
• Innervates the skin of anterolateral leg and most of the dorsal foot

Front 53

deep fibular (peroneal) nerve

Back 53

• Innervates the muscles of the anterior compartment of the leg and the dorsal foot
• Innervates the skin of the dorsal foot between the hallux and second digit

Front 54

foot drop

Back 54

If the common fibular nerve is severed where it wraps around the neck of the fibula, all of the muscles in the anterior and lateral compartments of the leg and the dorsal foot will be paralyzed. The patient will present with foot drop, which is caused by the loss of dorsiflexion and toe extension.

Front 55

anterior compartment of leg

Back 55

• Actions: dorsiflex ankle joint and extend toes
• Innervation: deep fibular nerve
• Tendons pass deep to the superior and inferior extensor retinacula


tibialis anterior
extensor hallucis longus
extensor digitorum longus
fibularis (peroneus) tertius

Front 56

tibialis anterior

Back 56

Origin: lateral tibial condyle, tibial shaft & interosseous membrane
Insertion: medial cuneiform & base of first metatarsal
Action: dorsiflex ankle joint and invert foot

Front 57

extensor hallucis longus

Back 57

anterior compartment of leg; inn by deep fibular nerve
Origin: fibular shaft & interosseous membrane
Insertion: distal phalanx of the hallux
Action: extend hallux (MTP & IP joints); weakly dorsiflex ankle joint

Front 58

extensor digitorum longus

Back 58

anterior compartment
Origin: lateral tibial condyle, fibular shaft & interosseous membrane
Insertion: distal phalanges of digits 2-5
Action: extend digits 2-5 (MTP, PIP, & DIP joints); dorsiflex ankle joint

Note: the extensor digitorum longus and extensor hallucis longus tendons form extensor expansions on the dorsal surface of the phalanges

Front 59

anterior tibialis strain (shin splints)

Back 59

result from repeated microtrauma of the tibialis anterior muscle, and small tears in the periosteum overlying the tibia; usually due to overexertion of muscles in the anterior compartment (especially tibialis anterior)

Front 60

arteries around ankle

Back 60

Around the ankle, the posterior tibial artery gives off medial malleolar and calcaneal branches while the fibular a. gives off lateral malleolar and calcaneal branches (form anastomoses around ankle joint)

Front 61

fibularis (peronieus ) tertius

Back 61

part of anterior compartment
May be absent (~8%) or fused with extensor digitorum longus
Origin: distal fibular shaft & interosseous membrane
Insertion: base of fifth metatarsal
Action: dorsiflex ankle joint; evert foot

Front 62

dorsal foot

Back 62

two muscles on the dorsal aspect of the foot (located deep to the extensor digitorum longus tendons and superficial to the dorsal interossei)

Innervation: deep fibular nerve


extensor digitorum brevis
extensor hallucis brevis

Front 63

extensor digitorum brevis

Back 63

part of dorsal foot
Insertion: extensor expansions of digits 2-4
Action: extend digits 2-4 (MTP, PIP, & DIP joints)

Front 64

extensor hallucis brevis

Back 64

Varies in its degree of separation from extensor digitorum brevis
Insertion: extensor expansion of the hallux
Action: extend hallux (MTP & IP joints)

Front 65

lateral compartment of leg

Back 65

• Actions: evert foot and weakly plantarflex ankle joint
• Innervation: superficial fibular nerve
• Tendons pass deep to the superior and inferior fibular retinacula

fibularis (peroneus) longus
fibularis (peroneus) brevis

Front 66

fibularis (peroneus) longus

Back 66

Origin: head & proximal fibular shaft
Insertion: base of first metatarsal & medial cuneiform
Action: evert foot; weakly plantarflex ankle joint
Note: its tendon passes posterior to the lateral malleolus, enters a groove on the plantar aspect of the cuboid, and crosses the sole of the foot obliquely to reach its insertion

Front 67

fibularis (peroneus) brevis

Back 67

Origin: distal fibular shaft
Insertion: tuberosity of the fifth metatarsal
Action: evert foot; weakly plantarflex ankle joint
Note: its tendon passes posterior to the lateral malleolus

Front 68

arteries of lateral compartment

Back 68

o Supplied primarily by branches of the fibular artery (a branch of the posterior tibial a.)

Front 69

arteries of anterior compartment

Back 69

o Anterior tibial artery (branch of the popliteal a.) passes through gap in superior border of interosseous membrane, descends along the membrane with the deep fibular nerve
o Terminates at the ankle, where it becomes the dorsalis pedis artery

Front 70

arteries of dorsal foot

Back 70

o The dorsalis pedis artery (or dorsal artery of the foot) is the major source of blood to the toes (it does anastomose with the deep plantar arch)
o Major branches
• Arcuate artery
• Dorsal metatarsal arteries
• Dorsal digital arteries
o The dorsalis pedis pulse can be palpated on the dorsal aspect of the foot, just lateral to the tendon of extensor hallucis longus

Front 71

veins of anterolateral leg and dorsal foot

Back 71

o Deep veins accompany the arteries and share their names (however, there is no dorsalis pedis vein)
o Superficial drainage of the dorsal foot is via the dorsal venous arch
• Receives tributaries from the dorsal digital and metatarsal veins
• Anastomoses with the plantar venous arch in the sole of the foot
• Drains into great saphenous vein medially, and small saphenous vein laterally