The Posterior Leg

Question 1

Define the term leg:

Answer 1

Region between the knee and the ankle
Surrounded by crural fascia
The muscles move the ankle and toes
Made up of 3 compartments - posterior, anterior and lateral

Question 2

Give a brief overview of the posterior compartment of the leg:

Answer 2

Made of 7 muscles
3 superficial - Soleus, Plantaris, Gastrocnemius
4 deep - Tibialis posterior, popliteus, Flexor Digitorum longus and Flexor Hallucis longus
Innervated by tibial nerve
Action is plantar flexion except popliteus

Question 3

Describe the gastrocnemius:

Answer 3

Part of superficial posterior leg
Originates at medial and lateral femoral condyles
Inserts at the Calcaneal tendon
Function - explosive plantar flexion actions jumping and sprinting, also flexes knee
Nerve innervation - tibial nerve
Lies superficially over the soleus

Question 4

Describe the soleus

Answer 4

Originates from the fibula and soleal line of tibia
Inserts in Calcaneal tendon
Function -
Standing (prevents body falling forward) by providing enough plantar flexion
Musculovenous pump - compresses veins in your calf pumping blood back to heart

Innervated by tibial nerve
Lies deep to gastrocnemius

Question 5

Describe the plantaris:

Answer 5

Originates at lateral supraepicondylar line of femur
Inserts at the Calcaneal tendon
Very weak plantarflexion/knee flexion so main function is proprioception
Proprioception = perception of one’s own body position & movement
Innervated by tibial nerve
Gastrocnemius lies superficially and soleus lies deep to planataris

Question 6

Describe the origin, insertion and function of the popliteus:

Answer 6

Originates at the lateral femoral condyle
Inserts at the posterior proximal tibia
2 functions - laterally rotate femur or medially rotate femur

Standing position;
Knee in close packed (locked) position
Position with max contact between bones, stability, force transmission & taut ligaments
To allow flexion, popliteus must unlock knee
laterally rotate femur 5° relative to the tibia

Walking;
Knee locks again at the end of the leg swing but this straight (locked) knee must bend before heel strike to absorb impact
Easier to move unplanted tibia so this time
popliteus medially rotates tibia 5° relative to the
femur

Question 7

What is deep vein thrombosis ?
Include symptoms, risk factors and treatment

Answer 7

Thrombi may travel and block pulmonary arteries causing a pulmonary embolism
Embolus - any material travelling in bloodstream that may block vessels
DVT symptoms - swollen, achy
PE symptoms - chest pain, collapse, death
Risk factors - stasis (slow blood flow), hyper coagulability, obesity
Treatment - anticoagulants, filters that catch clots

Question 8

What is the tarsal tunnel ?

Answer 8

The tarsal tunnel is located on the medial aspect of the ankle and runs between the medial malleolus and the calcaneus
TT is posterior to the medial malleolus and deep to the flexor retinaculum

Contents anterior to posterior - “Tom Dick + A Very Nervous Harry”
Tibialis posterior
Flexor digitorum longus
Posterior tibial artery
Posterior tibial vein
Tibial nerve
Flexor Hallucis longus

TT serves as a protective passageway for nerves, tendons passing through
The flexor retinaculum holds the tendons in place as they slide through the tunnel

Question 9

What are shin splints ?

Answer 9

Medial tibial stress syndrome
Repetitive-stress injury of shin area
Pain in anteromedial or posteromedial tibia
Periostitis & microfractures of cortical bone
Possibly associated with muscle fibre traction at sites of attachment points of soleus, flexor digitorum longus, tibialis anterior or deep fascia
Often due to biomechanical abnormalities or training errors (e.g. insufficient cooldown/warmup, increased activity)
Treat with RICE, modify training regimen, calf stretching, shock-absorbing shoes, orthotics

Question 10

What are the superficial structures of the posterior leg ?

Answer 10

Common fibular nerve branches into lateral sural cutaneous nerve
Tibial nerve branches into medial sural cutaneous nerve
Medial and lateral sural nerves merge in the middle of the posterior calf to form the sural nerve
Sural n. runs through crural fascia
Sural n & Small saphenous v travel together in the superficial fascia of the posterior leg
Saphenous vein important for venous return and sural nerve for sensory innervation

Question 11

Describe the muscles of the deep posterior leg:

Answer 11

Popliteus:
origin - Lateral femoral condyle
insertion - Posterior proximal tibia
Unlock & weakly flex knee

Flexor Hallucis Longus:
origin - Fibula, Interosseous membrane
insertion - Distal phalanx 1
action - flex hallux + plantar flex

Tibialis posterior;
Origin - fibula, interosseous membrane, tibia
Insertion - Navicular, Cuneiforms, Cuboid, 2-4 Metatarsals
Action - plantar flex, inversion

Flexor Digitorum longus:
Origin - tibia
Insertion - distal phalanges 2-5
Action - flex digits 2-5