Distal Neurovasculature - Ankle & Foot Flashcards
What is the venous drainage of the lower limbs?
Superficial:
Dorsal venous arch of foot drains into saphenous veins that form the superficial venous drainage route and include:
1. Small/short: pass posterior to lateral malleolus (w/ the sural n.)
2. Great/long: pass anterior to medial malleolus (w/ the saphenous n.)
Deep:
Superficial veins located superficial of the deep fascia and drain into deep veins that pass from posterior leg as the posterior tibial then popliteal towards femoral triangle to become the femoral vein
What can the great/long saphenous vein be used for?
- Spare part for grafting procedures (CABG)
- Accessed via venous cut-down in emergencies to insert a cannula when peripheral cannulation is difficult e.g. trauma, burns or hypovolaemic shock
What is the route of the great/long saphenous vein?
- Anterior to medial malleolus
- Along posterior region of medial tibial border alongside saphenous n.
- Passes 4 finger breadth (7-10cm) posterior to the patella
- Passes through saphenous opening in a zone 1-4cm lateral and 0-3cm inferior to the pubic tubercle
- Goes deep into the femoral triangle to join the femoral vein
What is the route of the small/short saphenous vein?
- Passes from lateral foot posterior to lateral malleolus
- Ascends midline posterior leg alongside sural cutaneous n.
- Travels deep into popliteal fossa via crural fascia joining the popliteal vein
What is a varicose vein? What symptoms will the patient have? What conditions can predispose to formation of varicose veins?
Swollen and enlarged veins that usually occur on the legs and feet being blue/dark purple, lumpy, bulging or twisted in appearance. The patient may experience aching, heavy and uncomfortable legs, burning/throbbing legs, muscle cramps in leg (esp. at night), swollen feet/ankles and dry/itchy/thin skin over the area. They often run in families and in overweight/obese individuals. They are more common in females and in pregnancy.
What might be the consequence of damage to the sural nerve?
Paraesthesia or sensory loss in the calf region
What is between the gastrocnemius and soleus muscles?
Part of the deep venous drainage system: extensive venous plexus (where DVT occurs)
Why is knowledge of the deep venous system important?
Immobilised patients are at high risk of deep vein thrombosis which is why patients must mobilise soon after surgery - be suspicious if pain is reported in lower limb and make sure to look and examine limb as it will be red, swollen and hot
What might increase a persons risk of deep vein thrombosis (DVT)?
Stasis > 60 years old Overweight/obesity Smoking Dehydration Hypercoagulability
What are the 4 borders of the popliteal fossa?
Top L: Biceps femoris
Top R: Semimembranosus and semitendinosus
Bottom: Lateral and medial head of gastrocnemius
What does the tibial nerve supply?
Posterior leg and dorsal foot
What is the nerves of the lower limb?
- Superficial and lateral in popliteal fossa is the sciatic branching into common fibular and tibial n.
- Common fibular n. passes around fibula neck superficially
- Splits off into superficial fibular and deep fibular n.
- Superficial fibular n. innervates lateral leg compartment muscles and skin over most of the dorsal foot
- Deep fibular n. innervates the anterior leg compartment muscles, muscles of dorsal foot and skin between digits 1 and 2
- Tibial n. runs in anterior compartment in company of anterior tibial artery
What will occur if the lower limb nerves are damaged?
Common fibular: inability to dorsiflex causing foot-drop and high-knee, toe-heel (tap-tap) or circumduction gait
Deep fibular: foot-drop if proximally damaged
Superficial fibular: inability to prevent foot inversion
What is the thighs arterial supply?
- Femoral artery subcutaneous within femoral triangle (vulnerable in stab injury/surgery) then under sartorius through adductor hiatus into popliteal fossa
- Profunda femoris/deep femoral branch passes close to femoral neck alongside femoral shaft and passes through adductor magnus
- Popliteal artery passes through popliteal fossa close to supracondylar part of femur (vulnerable in femoral # and bleeds)
What is the leg arterial supply?
- Popliteal artery splits into anterior tibial and posterior tibial artery
- Anterior tibial artery passes deep in anterior leg compartment anterior to interosseous membrane running alongside deep fibular n.
- Anterior tibial artery passes onto dorsal foot as dorsalis pedis artery between EDL and EHL tendon and becomes the arcuate artery
- Posterior tibial artery passes under soleal arch deep in posterior leg compartment (and also gives off a fibular artery branch supplying lateral leg)
- Posterior tibial artery passes posterior to medial malleolus in tarsal tunnel into deep plantar arch on sole of foot
What are the consequences/examination finds associated with a blockage of the femoral artery in the anterior thigh?
Limb will be cold and the patient will experience pain which gets worst upon activity and goes away with rest (intermittent claudication) so they will be able to do less activity than before
What is the tarsal tunnel?
A flexor retinaculum covered canal between the calcaneus bone and medial malleolus that contains (from anterior to posterior):
- Tibialis posterior
- Flexor digitorum
- Posterior tibial artery
- Vein
- Tibial n.
- FHL
What can happen to tendons if they wear excessively on the bone they pass around? What symptoms will the patient have? What could consequently happen to the arches of the feet?
The tendons can rupture under excessive wear and tear causing pain and collapsed and flattened arches of the feet
What is the ankle joint?
Synovial hinge joint between talus, tibia and fibula that permits dorsiflexion and plantarflexion (least stable) - supported by strong collateral ligaments
What is the function of the 4 medial collateral (deltoid) ligaments?
Prevent excess foot eversion but damaged by excess foot eversion (named tibio-x e.g. tibio-calcaneal)
What is the function of the 2 lateral collateral ligaments?
Prevent excess foot inversion and damaged be excess inversion (named x-fibular e.g. calcaneo-fibular and talofibular)
What is the most commonly damaged ligament in the ankle? How is it damaged?
Anterior talofibular (lateral collateral) ligament via excess inversion and plantarflexion - malleoli and 5th metatarsal tuberosity are subject to avulsion fractures from in/eversion or rotation stress too
What test can be used to examine the anterior talofibular ligament for tears or sprains?
Anterior drawer test: pull foot forward stabilising leg above ankle and if the ligament is damaged, the foot will be able to be pulled much further forward and this will cause pain (pain on palpation too)
What must you do if you find a malleolar fracture?
Check the proximal leg as external rotation of the foot can also fracture the fibula (Maisonneuve fracture)
What are the Ottawa ankle rules that demonstrate an indication for imaging?
Lateral:
- Pain/tenderness in lateral malleolus zone
- Bone tenderness on posterior edge of top of lateral malleolus
- Bone tenderness on posterior edge of tip of medial malleolus
- Inability to weight bear for 4 steps immediately and in ED
Medial:
- Pain in mid foot zone
- Bone tenderness at base of 5th metatarsal
- Bone tenderness at navicular bone
- Inability to weight bear for 4 steps immediately and in ED
What joints of the foot are responsible for inversion and eversion movements?
- Subtalar (talarcalcaneal)
Transverse tarsal joint line:
- Talonavicular (synovial ball + socket joint)
- Calcaneocuboid
_____ is the axis of abduction:adduction.
2nd toe
What must you do if a patient has obtained a calcaneus fracture?
You must check there body all the way up to the brain as a huge amount of force is needed to break this bone i.e. jumping off a building and landing on heel - often patients obtain thoracolumbar vertebral wedge fractures (T12-L1) and C1 atlas Jefferson ring fractures (can detriment brain blood supply if vertebral arteries going through the holes are damaged as they form the basilar artery)
Define valgus and varus.
Valgus: distal part of bone of a joint is directed away from midline
Varus: distal part of bone of a joint is directed towards midline
What anterior leg tendons can be seen superficially on the dorsal foot?
All innervated by deep fibular nerve:
- Extensor digitorum and hallucis brevis
- Extensor digitorum and hallucis longus (dorsalis pedis artery sits lateral)
- Tibialis anterior
What are foot compartments? What are there clinical relevance?
The plantar foot is separated into 4 compartments and foot injury (e.g. by stepping on something) can infect a single compartment causing compartment syndrome which is extremely painful due to tight plantar fascia on sole of foot
What are eponychium? What is their clinical relevance?
Proximal and lateral folds that flank nails that can become infected (paronychia) which can be treated by topical antibiotics (dont normally need systemic ones) but also used for a wing block anaesthetic to anaesthetise the nail bed allowing the nail to be peeled off
What surrounds tendons at points of wear, friction and direction change? What is the relevance of this?
Synovial sheaths - can be routes for infection spread (tenosynovitis)
What is the sensory innervation of the foot?
Plantar:
- Medial plantar mostly
- Lateral plantar
- Saphenous
- Sural
- Tibial
Dorsal:
- Superficial fibular mostly
- Deep fibular
- Sural
- Saphenous
What happens if the sensory innervation to the foot is lost for example, in peripheral neuropathy?
Small injuries will build up as the patient cannot feel them which can cause extensive damage and ulceration over time
What nerves can be locally anaesthetised so radical procedures can be performed on the foot?
- Saphenous
- Deep and superficial fibular
- Tibial (via plantar)
- Sural
What is the function of foot arches?
- Absorb shock
- Distribute weight
- Stores forces for energy release during walking
What are the different arches of the foot?
- Medial: calcaneus to 1st/2nd metatarsal
- Lateral (lower than medial): calcaneus to 5th metatarsal
- Transverse: runs below the 5 digits from toe 1 to 5
What forms the arches of the foot?
Bones
Soft tissues
What problems might a patient experience if they have flat feet?
Pes planus (primary or secondary): pain on inside of arch, heel or ankle, generalized foot fatigue, shin pain, aching of knee/hip/lower back, inability to keep up with physical exercise and over time, rolling in of the foot/ankle and tilting outwards of heel and excessive inner heel wear pattern may be seen on shoes
What soft tissue structures support the foot arches?
- Long and short plantar ligaments tying front and back ends of arches together
- Intrinsic foot muscles tie front and back ends of arches together as well
- Tendons supporting arch from above when contracted: tibialis anterior, tibialis posterior, FDL and FHL
What are the intrinsic muscles of the foot? What is their innervation?
Arranged in 4 layers but be aware of:
- Interossei (between bones)
- Abductor hallucis brevis (pull big toe medially away from other toes)
- Abductor digiti minimi (pull little toe laterally away from other toes)
Innervated by medial and lateral plantar nerves (S1-2) from tibial n.
- FDL
- FHL
What are the functions of the intrinsic muscles of the foot?
- Support foot arches
- Act as dynamic ligaments that store and release energy during walking, locomotion and gait
- Support digits and big toe at push-off esp. AbHB and AdHB stopping it moving side-side + FHL
What will happen if the intrinsic muscles of the foot become weakened or damaged?
Arch collapse (secondary pes planus) so patient will become unstable on walking and digits will splay out unnaturally when foot hits the floor
What are the arterial and nerve supply of the foot?
- Posterior tibial artery enters planar foot branching into medial and lateral plantar arteries forming a plantar arch
- Anterior tibial artery forms dorsalis pedis artery which branches deep as well so blood supply to foot is rich and anastomic
- Nerves also called medial and lateral plantar and travel with arteries
- Digital arteries/nerves pass along sides of digits on plantar and dorsal foot
What is Morton’s neuroma?
A growth on a digital nerve passing between digits 3 and 4 that is very painful upon walking and palpation - often requires surgery to remove growth and alleviate symptoms
What is plantar fasciitis?
A wearing of the plantar aponeuroses that binds tightly to the skin on sole of foot and calcaneus due to repeated/excess tension meaning some fibres become torn/damaged or they are pulled of the medial calcaneal tubercle so patients will experience pain exacerbated by passive digit dorsiflexion or pressure over medial calcaneal tubercle and they will also feel pain when they stand, walk or run
