• Calcaneus
• Talus
• Navicular
• Cuboid
• Medial Cuneiform
• Intermediate Cuneiform
• Lateral Cuneiform

1. Articulations – Tibia & Fibula Superiorly; Calcaneus Inferiorly; Navicular Anteriorly
2. Landmarks – Body with Trochlea, Neck & Head; Posterior Process with Lateral & Medial Tubercles (creates groove for Flexor Hallucis Longus tendon)

1. Articulations – Talus Posteriorly; Cuneiforms Anteriorly; Cuboid laterally
2. Landmarks – Navicular Tuberosity

1. Articulations – Calcaneus Posteriorly; 3^rd Cuneiform and Navicular Medially; 4^th & 5^th Metatarsal Bones Anteriorly
2. Landmarks – Tuberosity of the Cuboid; Groove for Fibularis Longus Tendon

1. Articulations – Navicular Posteriorly; Base of Appropriate Metatarsal Bones Anteriorly; Lateral Cuneiform with Cuboid Laterally
2. Landmarks - None

• Articulations – Proximally with Cuneiform and Cuboid; Distally with Proximal  Phalanges
• Landmarks – Base, Body & Head; Tuberosity of 5^th Metatarsal

• Articulations – Proximal with Metatarsal Heads; Interphalangeal
• Landmarks – Base, Body & Head

• _____ – Extension of crural fascia to fibula. Separates the anterior compartment from the lateral compartment.

• Anterior Intermuscular Septum – Extension of crural fascia to fibula. Separates the anterior compartment from the lateral compartment.

• _____ – Extension of crural fascia to fibula. Separates the lateral compartment from the posterior compartment.

• Posterior Intermuscular Septum – Extension of crural fascia to fibula. Separates the lateral compartment from the posterior compartment.

• _____ – Passes across the calf from the fibula to the tibia, subdivides the posterior compartment into superficial and deep layers.

• Deep Transverse Fascia – Passes across the calf from the fibula to the tibia, subdivides the posterior compartment into superficial and deep layers.

• _____ – Between the shafts of the tibia and fibula.  Provides areas for muscle attachments.

• Interosseous Membrane – Between the shafts of the tibia and fibula.  Provides areas for muscle attachments.

Muscles of the posterior compartment of the leg are divided into a superficial and deep group by the _____

Superficial group of posterior compartment of the leg- composed of _____ and _____

Superficial group- composed of triceps surae (gastrocnemius and soleus) and plantaris

1. Origin- 
1. Medial Head: Immediately superior to medial condyle of femur (posterior aspect)
2. Head: lateral condyle of Femur (lateral aspect)
2. Insertion- Posterior surface of calcaneus via calcaneal tendon
3. Innervation- tibial nerve S1, S2
4. Function- plantarflexes ankle (most effectively when knee is extended), raises heel during walking, flexes leg at knee

1. Origin- Head and proximal posterior surface of fibula; soleal line of tibia
2. Insertion- Posterior surface of calcaneus via calcaneal tendon
3. Innervation- tibial nerve S1, S2
4. Function- plantarflexes ankle, steadies leg on foot in weightbearing

1. Origin- inferior end of lateral supracondylar line of femur
2. Insertion- posterior surface of calcaneus; tendon blends with medial aspect of calcaneal tendon
3. Innervation- tibial nerve S1, S2 
4. Function weakly assists gastrocnemius

Deep Group- composed of popliteus as well as  “Tom, Dick, and Harry”. .. “Tom” being _____ , “Dick” being _____ and “Harry” being _____.  This expression is useful in remembering the order (anterior to posterior) in which the tendons pass posterior to the medial malleolus, deep to the _____.

Deep Group- composed of popliteus as well as  “Tom, Dick, and Harry”. .. “Tom” being tibialis posterior, “Dick” being flexor digitorum longus and “Harry” being flexor hallucis longus.  This expression is useful in remembering the order (anterior to posterior) in which the tendons pass posterior to the medial malleolus, deep to the flexor retinaculum.

1. Origin- lateral aspect of lateral condyle of femur; lateral meniscus
2. Insertion- posterior surface of tibia, superior to soleal line
3. Innervation- tibial nerve L4, L5, S1
4. Function- weakly flexes knee; “unlocks knee” (external rotation of femur on fixed tibia)

1. Origin- interosseous membrane, posterior tibia inferior to soleal line (lateral to flexor digitorum longus), posterior fibula
2. Insertion- tuberosity of navicular, cuneiforms, cuboid, bases of metatarsals 2-4
3. Innervation- tibial nerve L4, L5
4. Function- plantarflexes ankle, inverts foot, helps maintain medial longitudinal arch height during stance phase of gait (eccentric action)

1. Origin- posterior tibia inferior to soleal line (medial to tibialis posterior)
2. Insertion- bases of distal phalanges 2-5
3. Innervation- tibial nerve S2, S3
4. Function- flexes digits 2-5, plantarflexes ankle, supports longitudinal arches (passive tension)

1. Origin- inferior 2/3 of posterior fibula, interosseous membrane
2. Insertion- base of distal phalanx of great toe
3. Innervation- tibial nerve S2, S3
4. Function- flexes great toe, plantarflexes ankle, supports medial longitudinal arch (passive tension)

Neurovascular Relationships of Posterior Compartment- the _____ nerve and _____ vessels are located between the deep and superficial groups of muscles, deep to the _____

Neurovascular Relationships of Posterior Compartment- the tibial nerve and posterior tibial vessels are located between the deep and superficial groups of muscles, deep to the transverse intermuscular septum

3 Parts of the foot: 

• Hindfoot- talus, calcaneus
• Midfoot- navicular, cuboid, cuneiforms
• Forefoot- metatarsals, phalanges

• Dorsal Surface – thin; continuous with the inferior extensor retinaculum proximally and the plantar fascia posteriorly and laterally; flexor retinaculum is medial specialization and superior and inferior fibular retinacula are lateral specializations.
• Plantar Surface – thick; centralized region is the plantar aponeurosis (clinically known as “plantar fascia”) which gives off vertical septa that divides the sole of the foot into medial, central and lateral compartments.

• abductor hallucis
• flexor digitorum brevis
• abductor digiti minimi

• quadratus plantae
• lumbricals

• flexor hallucis brevis
• adductor hallucis
• flexor digiti minimi brevis

• plantar interossei (3)
• dorsal interossei (4)

1. Origin- medial tubercle of calcaneal tuberosity, flexor retinaculum, plantar aponeurosis
2. Insertion- medial side of proximal phalanx of great toe
3. Innervation- medial plantar nerve S2, S3
4. Function- abducts and flexes great toe at MP joint

1. Origin- medial tubercle of calcaneal tuberosity, plantar aponeurosis, intermuscular septa
2. Insertion- both sides of middle phalanges 2-5
3. Innervation- medial plantar nerve S2, S3
4. Function- flexes lateral four digits

1. Origin- medial and lateral tubercles of calcaneal tuberosity, plantar aponeurosis, intermuscular septa
2. Insertion- lateral side of base of proximal phalanx of 5^th digit
3. Innervation- lateral plantar nerve S2, S3
4. Function- abducts and flexes 5^th digit

1. Origin- medial surface and lateral margin of plantar calcaneus
2. Insertion- posterolateral aspect of FDL tendon
3. Innervation- lateral plantar nerve S2, S3
4. Function- assists FDL in flexes lateral 4 digits (straightens pull of FDL tendon)

1. Origin- tendons of FDL
2. Insertion- medial aspect of expansion over lateral four digits
3. Innervation
1. medial one- medial plantar nerve; S2, S3
2. lateral three- lateral plantar nerve; S2, S3
4. Function- flexes digits at MP joint, extends digits at IP joint

1. Origin- plantar surface of cuboid and lateral cuneiforms
2. Insertion- both sides of base of proximal phalanx of great toe (sesamoids in tendons)
3. Innervation- medial plantar nerve S2, S3
4. Function- flexes great toe at MP joint

1. Origin
1. Oblique head- bases of metatarsals 2-4
2. Transverse head- plantar ligaments of MP joints
2. Insertion- lateral side of base of proximal phalanx of great toe
3. Innervation- lateral plantar nerve S2, S3
4. Function- adducts 1^st digit, helps maintain transverse longitudinal arch

1. Origin- base of 5^th metatarsal
2. Insertion- base of proximal phalanx of 5^th digit
3. Innervation- lateral plantar nerve S2, S3
4. Function-  flexes 5^th digit at MP joint

1. Origin- bases and medial sides of metatarsals 3-5
2. Insertion- medial sides of bases of phalanges 3-5
3. Innervation- lateral plantar nerve S2, S3
4. Function- adducts digits 3-5 (toward 2^nd digit) and flexes digits 3-5 at MP joints

1. Origin- adjacent sides of metatarsals 1-5
2. Insertion- 
1. 1^st- medial side of proximal phalanx of second digit
2. 2-4^th- lateral sides of proximal phalanges 2-4
3. Innervation- lateral plantar nerve S2, S3
4. Function- abduct digits 2-4 (digit 2 abducts both medially and laterally) and flexes digits 2-4 at MP joints

• medial and lateral plantar nerves
• medial and lateral  plantar arteries

Muscles of the anterior compartment of the leg- tendons of these muscles are held in place by thickenings  of the crural fascia at the ankle, the extensor retinacula (superior and inferior).

• tibialis anterior
• extensor digitorum longus
• extensor hallucis longus
• fibularis tertius

1. Origin- lateral condyle of tibia, superolateral surface of tibia, interosseous membrane 
2. Insertion- medial cuneiform, base of 1^st metatarsal
3. Innervation- deep fibular nerve; L4, L5
4. Function- dorsiflexion of ankle, inversion of foot

1. Origin- lateral condyle of tibia, medial fibula, interosseous membrane 
2. Insertion- middle and distal phalanges 2-5
3. Innervation- deep fibular nerve L5, S1
4. Function- extension of  toes 2-5, dorsiflexion of ankle

1. Origin- middle part of anterior fibula, interosseous membrane
2. Insertion- base of distal phalanx of great toe
3. Innervation- deep fibular nerve L5, S1
4. Function- extension of great toe, dorsiflexion of ankle

1. Origin- inferior 1/3^rd of anterior fibula, interosseous membrane
2. Insertion- dorsal aspect of base of 5^th metatarsal
3. Innervation- deep fibular nerve L5, S1
4. Function- dorsiflexion of ankle, eversion of foot; may be a physiologic “strain gauge” to help prevent inversion ankle sprains (???)

• anterior tibial artery
• deep fibular nerve

• Anterior Tibial Artery: is a branch of the popliteal artery.  It begins inferior to popliteus and passes anteriorly through a gap in the superior part of the interosseus membrane and descends between tibialis anterior and extensor digitorum longus.  At the ankle joint, as it emerges below inferior extensor retinaculum, it becomes dorsalis pedis artery.  

• Deep Fibular Nerve: is one of the terminal branches of the common fibular nerve.  It enters the anterior compartment between fibularis longus and the neck of the fibula and then travels with the anterior tibial artery.  

• anterior tibialis strain 
• medial tibial stress syndrome- inflammation/microtrauma of the medial tibia and/or overlying periosteum

• fibularis longus
• fibularis brevis

1. Origin- head and superior 2/3 of lateral fibula
2. Insertion- base of 1^st metatarsal; medial cuneiform
3. Innervation- superficial fibular nerve; L5, S1, S2
4. Function- eversion of foot, plantarflexion of ankle

1. Origin- inferior 2/3 of lateral fibula
2. Insertion- base of 5^th metatarsal tuberosity
3. Innervation- superficial fibular nerve; L5, S1, S2
4. Function- eversion of foot, plantarflexion of ankle

• Vasculature is primarily derived from perforating branches of the fibular artery.  The proximal portion of the lateral compartment also receives blood from a perforating branch of the anterior tibial artery.  Unlike the other two compartments of the leg, the lateral compartment does not have an artery running through it.

• Superficial Fibular Nerve: is one of the terminal branches of the common fibular nerve.  The common fibular nerve approaches the lateral compartment by crossing the lateral head of gastrocnemius and wrapping around the neck of the fibula before dividing.  The superficial fibular nerve descends through the lateral compartment between fibularis longus and brevis before becoming cutaneous anteriorly on the distal half of the leg.  It supplies skin anterolaterally on the distal half of the leg and a substantial portion of the dorsum of the foot.

• extensor digitorum brevis
• extensor hallucis brevis

1. Origin- calcaneus, interosseous talocalcaneal ligament, inferior extensor retinaculum
2. Insertion- extensor digitorum longus tendons to digits 2-4
3. Innervation- deep fibular nerve L5, S1
4. Function- aids EDL in extension of digits 2-4

1. Origin- calcaneus, interosseous talocalcaneal ligament, inferior extensor retinaculum
2. Insertion- base of proximal phalanx of great toe
3. Innervation- deep fibular nerve L5, S1
4. Function- aids EHL in extension of great toe at MP joint

The deep fibular nerve divides along the dorsum of the foot into a _____ branch which innervates muscles on the dorsum of the foot and a _____ branch which is cutaneous to the dorsal base of 1^st and 2^nd digits.

The deep fibular nerve divides along the dorsum of the foot into a lateral branch which innervates muscles on the dorsum of the foot and a medial branch which is cutaneous to the dorsal base of 1^st and 2^nd digits.

Proximal Tibiofibular Joint

• Plane type of synovial joint
• Head of fibula and lateral condyle of tibia
• Articular capsule and anterior & posterior ligaments of the head of the fibula
• Slight movement during dorsiflexion & plantarflexion of the foot

• Fibrous joint (syndesmosis)
• Inferior tibia and fibula
• Interosseous membrane and anterior & posterior inferior tibiofibular ligaments
• No movement; integrity of this articulation is essential for stability of the ankle joint

• Anterior Talofibular Ligament
• Posterior Talofibular Ligament
• Calcaneofibular Ligament

• Tibionavicular Ligament
• Anterior Tibiotalar Ligament
• Posterior Tibiotalar Ligament
• Tibiocalcaneal Ligament

• passive resistance of the triceps surae and by the medial and lateral ligaments.

• medial and lateral ligaments.

• Articulation between the talus and calcaneus.
• Ligaments
• Medial and lateral ligaments of ankle- assist in retaining the talus on the calcaneus
• Talocalcaneal Interosseous Ligament

• Movements
• Inversion- Performed by tibialis anterior and posterior; resisted by lateral ankle ligaments
• Eversion- performed by fibularis longus, brevis and tertius; resisted by deltoid ligament

• Higher and more important than the lateral longitudinal arch
• composed of the calcaneus, talus, navicular, 3 cuneiforms, and 3 metatarsals
• The talar head is the keystone of the medial longitudinal arch
• Supported by the tibialis anterior and posterior

• Flatter than the medial longitudinal arch, rests on ground during standing
• Composed of the calcaneus, cuboid, and lateral 2 metatarsals

• Runs from side to side
• Composed of the cuboid, cuneiforms, and bases of the metatarsals
• The medial and lateral parts of the longitudinal arch serve as pillars for the transverse arch
• Supported by the “stirrup” effect of fibularis longus and tibialis posterior tendons

• Ankle Sprains – Nearly always an inversion injury
• Lateral Ligament – Damaged by excessive or rapid inversion.  Most commonly the anterior talofibular ligament is sprained.  May be accompanied by a fracture of the fibula.
• Medial Ligament – Damaged by excessive or rapid eversion.  

• _____ (“_____”) – Foot deformity characterized by lateral deviation of the great toe.

• Hallux Valgus (“bunion”) – Foot deformity characterized by lateral deviation of the great toe.

• _____ (“_____”) – often congenital, but may result from “fallen arches” (usually the medial parts of the longitudinal arches) or rupture of the tibialis posterior tendon

• Pes Planus (“flatfeet”) – often congenital, but may result from “fallen arches” (usually the medial parts of the longitudinal arches) or rupture of the tibialis posterior tendon

L1- inguinal region

L2- proximal anterior thigh

L3- medial knee

L4- medial ankle

L5- dorsum of foot

S1- lateral foot/ankle

S2- posterior calf

Cutaneous Distribution of Peripheral Nerves in the Lower Extremity

Thigh and Gluteal Regions

1. Subcostal Nerve- 

2. Iliohypogastric Nerve-

3. Ilioinguinal Nerve- 

4. Genitofemoral Nerve-

5. Lateral Femoral Cutaneous Nerve- 

6. Anterior Femoral Cutaneous Nerves (from femoral n.)- 

7. Obturator Nerve-

8. Posterior Femoral Cutaneous Nerve-

9. Cluneal Nerves (from dorsal primary rami except inferior cluneal nerves from posterior femoral cutaneous nerve)- 

Cutaneous Distribution of Peripheral Nerves in the Lower Extremity

Leg Region

1. Saphenous Nerve (from femoral) – Medial leg & foot.

2. Sural Nerve (from both tibial and common fibular) – Posterior & lateral leg; lateral foot.

3. Common Fibular Nerve – Lateral part of posterior leg and the knee joint.

4. Superficial Fibular Nerve – Distal 1/3^rd of anterior leg and dorsum of foot.

5. Deep Fibular Nerve – 1^st interdigital cleft. 

6. Medial Plantar Nerve (from tibial) – Medial side of sole of foot and sides of 1^st 3 digits.

7. Lateral Plantar Nerve (from tibial) – Sole lateral to a line splitting 4^th digit.