7 - Anterior and Lateral Leg Flashcards
What forms the anterior, lateral and posterior compartments of the leg?
Tibia, fibula, interosseous membrane, anterior and posterior intermuscular septa
What is the common action of the anterior compartment?
Dorsiflexion/extension
What bounds the anterior compartment?
Anteriorly: skin and deep fascia
Medially: LATERAL tibia
Posteriorly: interosseous membrane
Laterally: anterior intermuscular septa
Why is this compartment more vulnerable to compartment syndrome?
- it is bound on 3 sides by fairly rigid structures (tibia, fibula and interosseous membrane (tough and fibrous like fascia)
- unlike in the thigh there isn;t a lot of empty space and is tight
What are the muscles, nerve supply and blood supply to the anterior compartment of the leg?
- Tibialis Anterior
- Extensor Digitorium Longus (more anterior to hallucis)
- Extensor Hallucis Longus
- Peroneus Tertius
> Deep Peroneal Nerve
Anterior Tibial Artery
Where does the hip joint have the greatest range of movement?
The hip joint has the greatest range of movement in flexion and abduction, as the joint capsule is the most loose on the anterior and lateral aspects.
What connects the fibula and tibia?
Interosseous Membrane
What muscle lies between the femoral artery and profunda femoris?
Adductor Longus
Where do the muscles of the anterior compartment act?
- On the foot at the ankle joint proper to dorsiflex
- Some act on the subtalar to invert/evert
Where do the anterior tibial artery and deep peroneal nerve run?
Along the interosseous membrane, deep to Extensor Hallucis Longus and Tibialis Anterior
Tibialis Anterior?
O: Superior half of lateral tibia
I: Medial cuneiform and base of the 1st metatarsal
> Inversion and dorsiflexion
Nerve supply to the anterior compartment?
Deep Peroneal
Extensor Digitorum Longus
O: Lateral condyle of tibia, superior medial tibia and interosseous membrane (deep to tib ant)
I: Middle and distal phalanges of lateral 4 toes
> Extend toes and dorsiflex ankle
Extensor Hallucis Longus
O: Middle anterior fibula and interosseous membrane (deep to EDL)
I: Base of the distal phalanx of the great toe
> Extend great toe and dorsiflexes ankle
Peroneus Tertius
O: INFERIOR anterior fibula and interosseous membrane
I: Base of the 5th metatarsal
> Eversion and dorsiflexion
How is dorsiflexion balanced when walking?
Tibialis anterior inverts foot (medial cuneiform and 1st MT)
Peroneus Tertius everts foot (5th MT)
What are the muscles in the lateral compartment of the leg, what is the nerve supply and vascular supply?
Peroneus Longus
Peroneus Brevis
> Superficial Peroneal Nerve
> Peroneal Artery
Peroneus Longus
O: Superior lateral fibula
I: Base of the 1st MT and medial cuneiform
> goes posterior to the lateral malleolus, UNDER the foot and inserts to 1st MT and medial cuneiform
STRONG eversion, weak plantarflexion
Peroneus Brevis
O: Inferior lateral fibula (deep to peroneus brevis)
I: Base of the 5th MT
> also goes around the lateral malleolus
Eversion and weak plantarflexion
What muscles insert at the 5th MT?
Peroneus Tertius and Peroneus Brevis
What muscles insert at the base of the 1st MT and medial cuneiform?
Tibialis Anterior and Peroneus Longus
What is the retinaculum and what is its purpose?
- is thick bands of fascia
- the retinaculum holds down the tendons tight at the ankle joint and prevents bowstringing to maintain the line of pull
What are the retinaculum at the ankle?
Superior and inferior EXTENSOR Retinaculum (anteriorly)
Superior and inferior peroneal retinaculum (laterally)
Describe the superior extensor retinaculum
- band of deep fascia from the tibia to the fibula, superior to the malleoli
- binds down tendons of the ant comp to prevent bowstringing during dorsifexion
Describe the inferior extensor retinaculum
- Y shaped band of thickened deep fascia
- laterally attached from the calcaneous to the medial malleolus and the plantar aponeurosis
- at lateral insertion to the calcaneous the fibres link up to the inferior peroneal retinaculum
Superior and inferior peroneal retinaculum
Superior: Lateral malleolus > calcaneous
Inferior: Calcaneous > Inferior extensor retinaculum
Describe the path of the Sciatic Nerve
Sciatic Nerve (L4-S3)
> Splits in 2 at the back of the thigh to become the Common Peroneal Nerve and the Tibial Nerve
> Tibial N continues posterior while Common Peroneal splits in popliteal fossa goes lateral (superficial)/anterior (deep)
> Branch off of Tibial N and Common Peroneal form Sural Nerve which is cutaneous (S1)
What spinal nerves contribute to the Lumbosacral Plexus?
L2-S2/3
Nerves of the Sciatic Nerve?
L4 - S3
What spinal levels do each of the nerves from the sciatic nerve contain?
Same as the sciatic nerve - L4-S2
> Tibial, CPN, SPN, DPN
Dermatome of the sural nerve?
S1
Muscles innervated by DPN?
TA
EDL
EHL
PT
Muscles innervated by SPN?
PL
PB
Where does the deep peroneal nerve become cutaneous?
!st webspace
after supplying muscles in the dorsum of the foot
Where does the superficial peroneal nerve become cutaneous?
Anterior/lateral leg and most of the dorsum of the foot
Where does the CPN run?
- Wraps around head of the fibula and becomes very superficial (prone to damage)
- SPN stays superficial in lateral compartment and becomes very superficial 2/3 way down fibula and then splits and runs across the dorsum of the foot (very adherent to skin)
Describe the cutaneous supply to the foot
Lateral = SURAL nerve
Most of dorsum = superficial peroneal nerve
1st webspace = deep peroneal nerve
Medial = Saphenous Nerve (medial malleolus no sensation? May be femoral n damage)
Spinal nerve contributions to the Superior and Inferior Gluteal Nerves?
Superior = L4 - S1 Inferior = L5 - S2
Describe the arrangement of structures at the ankle from medial to lateral
The Hospitals Are Very Nasty Diseased Places
Tibialis anterior
ext Hallucis longus
Anterior tibial artery
anterior tibial Vein
deep peroneal Nerve
ext Digitorum longus
Peroneus tertiusDescribe the cutaneous supply of the lower limb
Femoral: anterior medial thigh
Obturator: medial thigh
Saphenous: Anterior medial leg and foot
Deep Peroneal: 1st webspace
Superficial Peroneal: dorsum foot and lateral anterior leg
Sural: Very lateral foot and lateral/posterior leg
Lateral cutaneous of the leg and thigh and posterior cutaneous
How does the tibial nerve terminate?
Medial and lateral plantar nerves
Where do the medial and lateral plantar nerves arise from?
Terminal Tibial nerve
Where does the popliteal artery trifurcate?
As it exits the popliteal fossa into the anterior tibial artery, posterior tibial artery and peroneal artery
Describe the pathway of the anterior tibial artery
- needs to get from the posterior to anterior
- passes anteriorly through a hole in the interosseous membrane and sits on membrane
- at the ankle joint it passes down the middle between EHL and deep peroneal nerve + EDL and becomes dorsalis pedis after passing under EHL
- dorsalis pedis gives off the Deep Plantar Artery, Lateral Tarsal Artery and Arcuate Artery
What branches does dorsalis pedis give off?
- Deep Plantar Artery
- Lateral Tarsal Artery
- Arcuate Artery
Where does the posterior tibial artery run?
- Deep to soleus
- in posterior compartment and runs with tibial nerve and posterior tibial vein
- eventually runs posterior to the medial malleolus
- at this point divides into the medial and lateral plantar arteries (supply sole of the foot)
Where does the peroneal artery run?
Runs laterally towards the fibula but still within the DEEP posterior compartment
Supplies both the lateral and posterior compartment
Why is the Dorsalis Pedis Artery so important?
- runs in line with the 2nd toe
- inobtrusive way to take pulse
- not invasive
- a good pulse here means there is a good supply to other body parts as extremities are supplied
- is 1st to disappear in vascular diseases and low BP
What nerve is likely to be injured in Foot Drop?
- in foot drop the passive position of the foot is plantarflexed and inverted
- the anterior/dorsiflexion compartment is affected
- common peroneal or deep peroneal nerves are injured
- results in high steppage gait and slapping gait as can’t pick up foot
Describe compartment syndrome in the lower leg
- is limb threatening and potentially life threatening
- most common in leg/forearm following trauma
- occurs when the pressure in a compartment exceeds arterial so there is no arterial supply to the compartment putting muscles and eventually nerves at risk of ischemia and necrosis
- when a bone breaks and IF the skin and fascia are still in tact this fills and increases pressure in the compartment
- there is no space for the pressure to dissipate to
What is the order of things affected in compartment syndrome?
- Veins - compress and so venous return decreases (not much of a problem but means more fluid building up)
- Arteries - everything supplied dies and everything DOWNSTREAM
- in 4-6 hours the muscle is dead and will not work again
- eventually nerves
How do you treat compartment syndrome?
- if there is compartment syndrome in any single compartment then ALL the compartments will be opened
- antero-lateral fascia incision
- postero-medially in fascia (avoid vessels - great saph etc)
- often see scars down each side of leg
- open from knee down to ankle for 2 weeks until pressure drops
- use a skin graph to close. Can take months to years to go down
What are the 5 clinical findings of compartment syndrome?
Pain - DEVELOPS (1st sign. Very painful) Pallor - pale as loss of blood supply Pulselessness - vessels compressed Paresthesia - numb (nerves later) Paralysis - nerve stops functioning
