Posterior Compartment Muscles

Question 0

How are the deep and superficial posterior muscles separated

Answer 0

The two layers are separated by a band a fascia

Question 1

Name the muscles of the superficial posterior compartment

Answer 1

Gastrocnemius
Plantaris
Soleus

Question 2

Name the muscles of the posterior deep compartment and innervation and arterial supply

Answer 2

Popliteus
Tibialus posterior 
Flexor digitorum longus
Flexor hallucis longus
Innervated by tibial nerve and posterior tibial artery.

Question 3

What is the function of the posterior mucsles?

What nerve are they innervated by?

Answer 3

They plantarflex and invert the foot.

They are innervated by the tibial nerve, a terminal branch of the sciatic nerve

Question 4

Where do all the superficial muscles insert into?
What roots do the calcaneal reflex test?
Name the 2 bursae associated with the calcaneal tendon?

Answer 4

All insert into the calcaneus via the calcaneal tendon.
The calcaneal reflex tests spinal roots s1 - s2.
Subcutaneous calcaneal bursa lies between the skin and the calcaneal tendon.
The deep bursa of the calcaneal tendon lies between the tendon and the calcaneus.

Question 5

Gastrocnemius name origin, insertion and action. Also name innervation and arterial supply.

Answer 5

Most superficial of all posterior muscles.
Origin: Has 2 heads, medial and lateral condyle sod femur.
Insertion: calcaneus via tendo Achilles
Action: powerful ankle plantarflexor (when knee is extended), flexes knee, inversion / supination if STJ

Innervated by tibial nerve and supplied by posterior tibial artery.

Question 6

Name the origin, insertion and action of Soleus

Answer 6

Soleus lies deep to gastrocnemius. It is large and flat, named Soleus due to its resemblance to a sole (flat fish)
Origin: from soleal line of tibia and upper fibula
Insertion: calcaneum via tendo Achilles
The muscle narrows in lower leg to join the calcaneal tendon.
Action: powerful ankle plantarflexor, supination of STJ

Question 7

Name origin, insertion and action of plantaris

Answer 7

Small muscle with long tendon- not very powerful
Origin: lateral condyle of femur
Insertion: calcaneum via tendo Achilles
Action: ankle plantarflexion, knee flexion, supination of STJ

Question 8

Which injury is usually sustained by forceful plantarflexion of the foot.
In which type of patient is this more likely to occur in?
How can this be tested?
What is the treatment?

Answer 8

Ruptured calcaneal tendon is usually sustained by forceful plantarflexion of the foot. Rupture refers to partial or complete tear of the tendon.
It is more likely to occur in people with a history of calcaneal tendinitis ( chronic inflammation)
The patient will be unable to plantarflex the foot against resistance and the foot will be permanently dorsiflexed. The Soleus and gastrocnemius can contract to form a lump in the calf region.
Treatment is usually non-surgical except in those with active lifestyles

Question 9

Name the muscles of the deep compartment including innervation and blood supply

Answer 9

4 muscles. 1 acts only on knee joint: popliteus whilst the other 3: tibialus posterior, flexor hallucis longus, flexor digitorum longus act on the ankle and foot.
Innervated by tibial nerve and blood supply is posterior tibial artery

Question 10

Popliteus name origin, insertion and action

Answer 10

Located superior you in leg. Lies behind the knee joint forming the base of the popliteal fossa.
Separated from knee joint by popliteus bursa.
Origin posterior tibia.
Attaches lateral condyle of femur.
Laterally rotates the femur, unlocking knee so that flexion can occur.

Question 11

Tibialus posterior name origin, insertion and action

Answer 11

Origin: tibia, fibula and interosseus membrane
Course: tendon passes medically behind medial malleolus
Insertion: tuberosity of navicular and all tarsal bones except talus
Action: inversion of STJ, assists ankle plantarflexion, supports MLA
Blood: posterior tibial
Nerve: tibial nerve (l4 & l5)

Question 12

When are posterior muscles active in gait cycle

Answer 12

During stance phase

Question 13

Flexor digitorum longus: name origin, insertion and action

Answer 13

Origin: medial side of posterior tibial
Course: passes behind medial malleolus deep to flexor retinaculum
Insertion: base of distal phalanx of lesser toes
Action: flexion of lesser IPJ’s, inversion of STJ and plantarflexion of ankle

Question 14

Flexor hallucis longus, name origin, insertion and action

Answer 14

Origin: lower 2/3 of fibula and interosseus membrane
Course: passes deep to flexor retinaculum, behind medial malleolus
Insertion: base of distal phalanx of hallux
Action: flexion of 1st IPJ, MTP, inversion of STJ and plantarflexion of ankle

Question 15

Name deep posterior muscle function during contact period of stance phase

Answer 15

To decelerate rapid probation of STJ that occurs after initial contact and decelerate internal rotation of the limb via eccentric contraction - mostly tib post

Question 16

Name deep posterior muscle function during midstance of contact phase

Answer 16

1. Fdl/ fhl stabilise the MTPs as momentum carries the body forward- to maintain the digits in the ground
2. Eccentrically contract to resist forward momentum of the body ( assists triceps surae)

Question 17

Name posterior deep muscle function during propulsive phase of contact period

Answer 17

Concentrically contract (shorten) during propulsion to plantarflex the ankle, re-supinate the STJ to act as a rigid lever and stabilise the digits

Question 18

What happens to muscles during concentric contraction

Answer 18

They shorten to allow for acceleration with lower force generated

Question 19

What happens to muscles during eccentric contraction

Answer 19

They lengthen to decelerate with high force generated