Sem 2 - K - Anterior/lateral leg & dorsum of foot - Interosseous membrane, superior tibiofibular joint, extensor retinaculum

Question 1

How many compartments are there in the leg?

What surface of the tibia is only covered by skin and fascia and has no muscle layer for protection?

Answer 1

We have

• Anterior compartment
• Lateral compartment
• Superficial posterior compartment
• Deep posterior compartment

The anteromedial surface of the tibia is only covered by skin and fascia

Question 2

The fibrous structure spanning the length of the tibia and fibula is the interosseous membrane What direction do the fibres off the interosseus membrane travel and why is this orientation of the fibres important?

Answer 2

The majority of the interosseous membrane fibres travel in an inferolateral direction from the tibia to fibula

This is important to help resist the downward pull of the muscles attached to the fibula - only one muscle pulls the fibula upwards - biceps femoris

Question 3

What artery pierces the interosseous membrane between tibia and fibula? What nerve does this artery run with?

Answer 3

The anterior tibial artery is one of the terminal branches of the popliteal artery and passes through a small opening in the interosseous membrane to come anteriorly

The anterior tibial artery descends in the anterior leg with the deep peroneal nerve

Question 4

What are the two tibiofibular joints? State what type of joint each is

Answer 4

Superior (proximal) tibiofibular joint is a synovial plane joint

Inferior (distal) tibiofibular joint is a syndesmosis - a type of fibrous joint

Question 5

What are the articulating surfaces of the superior tibiofibular joint?

What movement does this synovial plane joint allow for?

Answer 5

The articulating surfaces are between the articular facet on the head of the fibula and the articular facet on the lateral condyle of the tibia

During dorsiflexion of the ankle, the talus tends to wedge between the tibia and fibula causing slight movement of the superior tibiofibular joint

Question 6

What ligaments help to stabilize the superior tibofibular joints?

Which muscle provides support to this joint?

These all help the joint capsule of this joint

Answer 6

The anterior and posterior ligaments of the head of fibula (attaching from head of fibula to lateral tibial condyle)

As well as the lateral collateral ligament (lateral epicondyle of femur to lateral head of tibia)

Biceps femoris provides additional support to the superior tibiofibular joint

Question 7

What movements are possible at the ankle joint and state the muscles that can carry out each movement?

Answer 7

Dorsiflexion - Tibialis anterior, extensor digitorum longus, extensor hallucis longus, fibularis tertius

Plantarflexion - Gastrocnemius, soleus, plantaris, tibialis posterior, flexor digitorum longus, flexor hallucis longus, peroneus longus, peroneus brevis

Question 8

How many muscles are in the anterior and lateral compartments of the leg?

What is the main function of the muscles?

Where do the tendons of the compartments pass at the ankle?

Answer 8

4 muscle in anterior compartment of leg

• Extension of ankle joint and digits are the main function
• Tendons pass anterior to the ankle joint

2 muscles in lateral compartment of the leg

• Eversion of the foot is the main function
• Tendons pass posterior to the lateral mallelous

Question 9

Anterior compartment go anterior to the ankle joint and therefore this movement is dorsiflexion (ankle extension) Eversion of the foot is where you twist the foot so that the sole is facing laterally (opposite would be inversion where you twist the foot so the sole moves medially)

Are inversion and eversion movements of the foot or ankle? What muscles bring about these movements?

Answer 9

Inversion and eversion are not movements of the ankle joint but are movements of the foot

• Invertors of the foot Tibialis anterior and tibialis posterior
• Evertors of the foot Fibularis (peroneus) longus, brevis and tertius

Question 10

We will now discuss the muscles in the lateral compartment of the leg

• What are the muscles in this compartment?
• What is the nerve supply to these muscles?
• What movements do these muscles allow for?

Answer 10

Peroneus longus and peroneus brevis both supplied by the superficial peroneal nerve (L5, S1, S2 roots) All muscles with Peroneus (fibularis) cause eversion of the foot Because the tendons of the peroneus longus and brevis pass posterior to the lateral malleolus and therefore posterior to the ankle joint, they will also allow for plantarflexion of the ankle joint

Question 11

What are the attachments of the peroneus longus?

Answer 11

Peroneus longus attaches from head and upper 2/3rds of lateral fibula to the base of the 1st metatarsal and medial cuneiform

Question 12

Describe the course of the tendon of the peorneus longus?

Answer 12

The tendon passes posterior to the lateral mealleolus and then passes on the inferior side of the peroneal trochlea of the calcaenous before passing inferior to the cuboid bone (forming a groove) to travel to the medial side of the foot - base of 1st metatarsal and medial cuneiform

Question 13

What are the attachments of the peroneus brevis? (include the pathway for its tendon)

Answer 13

Peroneus brevis attaches to the inferior 2/3rds of the lateral fibula and its tendon passes posterior to the medial malleolus and then superior to the peroneal trochlea of the calcaneous to insert onto the tuberosity on the lateral side of the base of the 5th metatarsal

Question 14

What are the two tendons of the lateral compartment of the leg separated by?

What bone does the tendons of the peorneus muscles form a groove in?

Answer 14

The two tendons are separated by the peroneal trochlea of the calcaneous - peroneus brevis runs superior, peroneus longus runs inferior

The two tendons form a groove on the lateral malleolus - lateral malleolar sulcus Peroneus longus also forms a groove on the inferior surface of the cuboid bone

Question 15

What are the muscles of the anterior compartment of the leg and what is the nerve supply?

Answer 15

Tibialis anterior Extensor digitorum longus Extensor hallucis longus Fibularis tertius

All supplied by deep peroneal nerve (L4,5)

Question 16

Lateral comparmtent - superficial fibular nerve (L5, S1,2) Anterior compartment - deep fibular nerve (L4,5) Largest anterior compartment muscle is the tibialis anterior What are the attachments of this muscle?

Answer 16

Attaches from the lateral condyle of tibia, superior 1/2 of lateral surface of tibia and interosseous membrane

Crosses ankle joint anterior before heading to medial aspect of foot Inserts at the medial and inferior surfaces of the medial cuneiform and the base of the 1st metatarsal

Question 17

State again the attachments of the tibialis anterior and what is its function?

Answer 17

Tibialis anterior

Attaches

• from the lateral condyle of the tibia, superior 1/2 of the lateral tibial surface and interosseus membrane and inserts into the medial and inferior surfaces of the medial cuneiform and the base of the 1st metatarsal

Function -

• dorsiflexes the ankle and inverts the foot

Question 18

What are the attachments of the extensor digitorum longus? Where does EDL lie in relation to tibialis anterior?

Answer 18

Extensor digitorum longus attaches from lateral condyle of tibia, superior 3/4 of medial surface of the fibula and interosseus membrane to the middle and distal phalanges of the lateral 4 digits EDL lies adjacent to the tibialis anterior on its lateral side

Question 19

State again the attachments of the extensor digitorum longus and its function

Answer 19

EDL attaches from the lateral condyle of tibia, superior 3/4 of medial surface of the fibula and interosseous membrane to insert onto the middle and distal phalanges of the lateral 4 digits

• Function - extension of the lateral 4 digits, dorsiflexes the ankle

Question 20

What muscle is the extensor hallucis longus found between? What are the attachments of the extensor hallucis longus?

Answer 20

The extensor hallucis longus is found betweenthe tibialis anterior and extensor digitorum longus

The EHL attaches from the middle anterior surface of the fibula and interosseous membrane and inserts into the dorsal aspect of the distal phalnyx of the big toe (hallux)

Question 21

State again the attachment of the extensor hallucis longus and its function?

Answer 21

Extensor hallucis longus attaches from the middle anterior surface of the fibular and interosseous membrane and inserts into the dorsal aspect of the distal phalnyx of the hallux

Function - Extension of the big toe and dorsiflexion of the ankle joint

Question 22

The peroneus tertius is a very small muscle What is its attachment? What muscle does it tend to blend with?

Answer 22

Peroneus tertius attaches from the inferior 1/3 of the anterior fibula and interosseous membrane and inserts onto the dorsum of the base of the 5th metatarsal The muscle belly can tend to blend with the extensor digitroum longus

Question 23

State again the attachments of the peroneus tertius and its function

Answer 23

Attaches from the inferior 1/3rd of the anterior fibula and interosseous membrane Inserts onto the dorsal aspect of the base of the 5th metatarsal Function - dorsiflexion of the ankle, assists in eversion of the foot

Question 24

RESTATE THE ATTACHMENTS OF THE MUSCLES OF THE ANTERIOR COMPARTMENT OF THE LEG

Answer 24

• TIBIALIS ANTERIOR - lateral condyle of tibia, superior 1/2 of lateral surface of tibia & interosseous membrane to insert onto medial & inferior surfaces of medial cuneiform and base of 1st metatarsal
• EXTENSOR DIGITORUM LONGUS - lateral tibial condyle and superior 3/4 of medial surface of fibula and interosseous membrane to insert onto the middle and distal phalanyx of lateral 4 digits
• EXTENSOR HALLUCIS LONGUS- middle anterior surface fibula & interosseous membrane to insert onto the dorsal aspect of distal phalnyx of hallux
• PERONEUS TERTIUS - inferior 1//3 anterior fibula and interosseous membrane to insert onto the dorsum of base of 5th metatarsal

Question 25

What happens when walking if there is injury to the common peroneal nerve or deep peroneal nerve?

Answer 25

When walking the dorsflexors are meant to extend the ankle joint to lift the foot away from the ground, if there is injury to the nerve supply to these muscles the foot will drag along the ground

Question 26

There is a retinaculum associated with the ankle joint (both an extensor and flexor retinaculum) What are the two extensor retinaculum?

Answer 26

We have the superior and inferior extensor retinaculum

Question 27

Where does the superior extensor retinaculum attach from?

Answer 27

Superior extensor retinaculum attaches from anterior border of tibia to lower end of fibula

Question 28

Where does the inferior extensor retinaculum attach from?

Answer 28

Inferior extensor retinaculum is Y shaped with a common origin from the calacaneous laterally * The upper limb attaches to the medial malleolus * The lower limb passes round the medial border of the foot and blends with dense fascia over the abductor hallucis (medial part of plantar fascia)

Question 29

What are the two intrinsic muscle of the dorsum of the foot and what is their common origin? What is their nerve supply?

Answer 29

Extensor digitorum brevis and Extensor hallucis brevis * These muscles originate from the superior surface of the calcaneous and the inferior extensor retinaculum * Both supplied by the deep peroneal nerve (L5,S1)

Question 30

* Anterior compartment of leg muscle - deep fibular nerve (L4,5) * Lateral compartment of leg muscles- superficial fibular nerve (L5, S1,2) * Dorsum of foot muscles - deep fibular nerve (L5, S1) What is the attachment of the extensor digitroum brevis, its function and nerve supply?

Answer 30

Extensor digitorum brevis arises from the superior surface of the calcaneous and inferior extensor retinaculum and inserts onto the long extensor tendons of toes 2-4 * Function - extension of digits 2-4 * Nerve supply - deep peroneal nerve (L5,S1)

Question 31

What is the attachment of the extensor hallucis brevis, its function and nerve supply?

Answer 31

Extensor hallucis brevis arises from the superior surface of calcaneous and inferior extensor retinaculum inserts onto the base of the proximal phalnyx of the big toe * Function - it extends the big toe * Nerve supply - deep peroneal nerve (L5, S1)

Question 32

Where does the common peroneal nerve branch?

Answer 32

The common peroneal nevre branches between the nec of the fibula and the peroneus longus (attaches at head and upper 2/3rds of lateral fibula) to form the superficial and deep peroneal nerve

Question 33

describe the route of the superificial fibular nerve?

Answer 33

The superficial fibular nerve runs in the lateral compartment of the leg supply the peroneus longus and brevis (L5, S1, S2) before continuing as a cutaneous nerve innervating distal anterior leg and most of the dorsum of the foot

Question 34

Describe the route of the deep peroneal nerve after its formation?

Answer 34

The deep peroneal nerve pierces/passes through the EDL and travels with the anterior tibial artery initially between EDL and tibialis anterior but more distally between EHL and tibialis anterior The deep peorneal nerve crosses the ankle joint to innervate the EHB and EDB and provides cutaneous innervation to the 1st web space

Question 35

* What supplies most of the cutaneous innervation to the lateral and anterior leg? * What supplies most of the cutaneous innervation to the dorsum of the foot? * What supplies cutaneous innervation to the 1st web space?

Answer 35

* Most of cutaneous innervation to lateral leg is the sural nerve (medial and lateral cutaenous branches) * Most of cutaneous innervation to anterior leg is the saphenous nerve * Most of cutaneous innervation to dorsum of the foot - superficial peroneal nerve * Cutaneous innervation to 1st web space - deep peroneal nerve

Question 36

What forms the sural nerve?

Answer 36

Fibres from the common fibular nerve form the lateral sural cutaneous nerve Fibres from the tibial nerve from the medial cutaenous sural nerve These branches merge at some point to form the sural nerve - hence why textbooks say it formed by bracnhes from tibial and common fibular nevre

Question 37

Describe the arterial supply to the leg?

Answer 37

* Popliteal artery divides to form anterior and posterior tibial artery * Posterior tibial artery supplies the posterior leg and gives a fibular artery branch which remains in posterior leg and gives perforating branches to the lateral compartment * Anterior tibial artery travels through the interosseous membrane and descends on this with the deep peroneal nerve

Question 38

What is the continuation of the anterior tibial artery at the ankle joint known as? What are the three branches from this continuation?

Answer 38

Anterior tibial artery continues as the dorsalis pedis artery once passed the ankle joint Gives three branches * \* Lateral tarsal artery * \* Arcuate artery * \* Deep plantar artery

Question 39

What does the arcuate artery anastamose with? What branches does it give?

Answer 39

The arcuate artery runs across the metatarsal giving metatarsal and digital arteries to anastamose with the lateral tarsal artery

Question 40

What does the deep plantar artery branch of the dorsalis pedis artery anastamose with?

Answer 40

Deep plantar artery passes to the sole of the foot to anastamose with the lateral plantar artery to form the deep plantar arch between layers 3 and 4 of the sole of the foot