The Leg & Ankle Anatomy Flashcards
What are the two articulations of the tibia?
the proximal tibia articulates with the medial and lateral condyles of the femur to form the knee joint
the distal tibia articulates with the talus at the ankle joint
Why does the tibia look triangular in cross section?
it has a medial, lateral and posterior surface
How is the fibula positioned relative to the tibia?
the fibula is much thinner than the tibia and is positioned more laterally
What are the articulations of the fibula?
it does NOT contribute to the knee joint
it articulates distally with the talus at the ankle joint
the tibia and fibula articulate with each other at their proximal and distal ends
What is within the space between the tibia and the fibula
interosseous membrane
this is a thick dense fibrous sheet of connective tissue
Label the features of the tibia and fibula
In which locations may the tibia be fractured?
- proximally
- mid-shaft
- distally - as part of an injury to the ankle
the tibia is a strong bone and a significant force is required to cause a mid-shaft fracture in a healthy tibia
As the tibia’s medial surface is extensive and superficial, what 2 clinical procedures is it exploited for?
- as a donor site for bone grafts
- interosseous “IO” access
IO access is obtained in emergencies when the peripheral vasculature is shut down and the superficial veins cannot be cannulated
What are the roles of the interosseous membrane?
- it is a fibrous joint that unites the tibia and fibula
- it separates the muscles of the anterior and posterior compartments of the leg
- it acts as an attachment site for muscles
What passes through the foramina of the interosseous membrane?
above the free concave border of the upper margin is a foramen for the passage of the anterior tibial vessels to the front of the leg
in the lower part there is a foramen for the anterior peroneal vessels
label the diagram
What is the role of the lateral intermuscular septae?
They separate the small lateral compartment of the leg from the anterior and posterior compartments
What is compartment syndrome?
it occurs when there is a large amount of pressure within a muscle compartment (bleeding or swelling)
this restricts blood flow to the area and can potentially damage the nerves and muscles
What are the 2 types of compartment syndrome?
acute:
- happens suddenly, usually after a fracture or severe injury
- is a medical emergency and requires urgent treatment
- can lead to permanent muscle damage if not treated quickly
chronic:
- happens gradually, usually during and immediately after repetitive exercise (such as running or cycling)
- usually passes within minutes of stopping the activity
- is not a medical emergency and does not cause permanent damage
What are the typical symptoms of acute compartment syndrome?
- intense pain, especially when the muscle is stretched, which seems much worse than would normally be expected for the injury
- tenderness in the affected area
- tightness in the muscle
- a tingling or burning sensation
- in severe cases, numbness or weakness (these are signs of permanent damage)
What are the typical symptoms of chronic compartment syndrome?
- cramping pain during exercise, most often in the legs
- swelling or a visibly bulging muscle
- a tingling sensation
- the affected area turning pale and cold
- in severe cases, difficulty moving the affected body part
What articulation is involved in the ankle joint?
the ankle is a synovial hinge joint formed by the articulation between the distal tibia, distal fibula and talus
the distal tibia and 2 malleoli form a ‘socket’ called the ankle mortise, into which the talus fits
What is shown by the yellow line?
the ankle mortise
formed by the distal tibia and the 2 malleoli
Label the diagram of the ankle joint
Is the ankle more stable in flexion or extension?
Why?
dorsiflexion (extension)
the talus is wedged in between the two malleoli
What are the two movements possible at the ankle joint?
dorsiflexion:
this is the toes up towards the leg
plantarflexion:
this is toes pointing to the floor
these movements are allowed by the contraction of the muscles in the anterior and posterior compartments of the leg, respectively
What are the 4 muscles in the anterior compartment of the leg?
- tibialis anterior
- extensor digitorum longus
- extensor hallucis longus
- peroneus (fibularis) tertius
Label the muscles of the anterior compartment
What movements are the anterior compartment muscles primarily involved in?
they act to dorsiflex and invert the foot at the ankle joint
What is the origin and insertion of tibialis anterior?
origin:
lateral surface of the tibia
insertion:
medial cuneiform and base of metatarsal I
What is the action and innervation of tibialis anterior?
action:
dorsiflexion and inversion of the foot
innervation:
deep fibular nerve
What action do extensor hallucis longus and extensor digitorum longus have on the toes?
they are extrinsic extensors of the toes
they originate in the leg but their tendons insert onto bones within the foot
the tendons cross the ankle joint as well as the toes
What is the origin and insertion of extensor digitorum longus?
origin:
tibia, anterior fibula and interosseous membrane
insertion:
middle and distal phalanges of digits 2-5
What is the action of extensor digitorum longus?
it extends the lateral 4 toes (2-5)
it is involved in dorsiflexion
What is the origin and insertion of extensor hallucis longus?
origin:
anterior fibula and interosseous membrane
insertion:
distal phalanx of the big toe
What is the action of extensor hallucis longus?
extends the great toe
dorsiflexion of the foot
What is the common innervation of extensor digitorum longus and extensor hallucis longus?
deep fibular nerve
What is the role of peroneus (fibularis) tertius?
What is significant about this muscle?
it assists in dorsiflexion of the ankle and eversion of the foot
it is not present in all individuals
What is meant by ‘shin splints’?
pain along the edge of the tibia due to inflammation of tissue in the area
complications may include stress fractures
From which vessel does the anterior tibial artery arise?
How does it gain access to the anterior compartment?
it originates at the distal end of popliteus muscle from the popliteal artery
it arises within the popliteal fossa and passes through the interosseous membrane to enter the anterior compartment
Which artery is shown?
What artery does the anterior tibial artery give rise to?
it travels over the anterior aspect of the ankle joint and into the foot as the dorsalis pedis artery
this is palpable on the dorsum of the foot
How are the muscles in the posterior group divided?
What is their innervation?
they are divided into a superficial and deep group by the transverse intermuscular septum
ALL muscles in the posterior leg are innervated by the tibial nerve
What are the 3 superficial muscles in the posterior leg?
- gastrocnemius
- soleus
- plantaris
What is the relationship between gastrocnemius and soleus?
gastrocnemius is more superficial than soleus
their tendons converge to form the calcaneal (Achilles) tendon
this inserts onto the calcaneum (heel bone)
What do the two large muscle bellies of gastrocnemius form?
the inferomedial and inferolateral boundaries of the popliteal fossa
label the muscles of the superficial compartment of the posterior leg
What are the origins and actions of gastrocnemius?
origins:
superior to articular surfaces of lateral and medial condyles of the femur
action:
plantarflexion of foot and flexion of knee
What are the origin and actions of soleus?
origin:
soleal line
action:
plantarflexion
What is the usual mechanism of Achilles tendon rupture?
it occurs when the tendon is stretched beyond its capacity
Forceful jumping or pivoting, or sudden accelerations of running, can overstretch the tendon and cause a tear
an injury to the tendon can also result in falling and tripping
What symptoms or signs would you expect if someone had ruptured their Achilles tendon?
sudden onset of sharp pain in heel
walking, standing on tiptoe, running or climbing stairs may become difficult
swelling in the calf and limp
bruising on the lower leg
How is the ankle jerk reflex tested in a peripheral neurological examination?
- hold the ankle in dorsiflexion
- tap the Achilles tendon with a tendon hammer
- tap the tendon superior to its insertion point on the calcaneum
What is seen in a normal ankle jerk reflex?
Which peripheral nerve and which spinal nerves/cord segments are being tested?
the foot jerks towards its plantar surface
this reflex tests if the S1 and S2 nerve roots are intact
failure of the foot to jerk can indicate sciatic nerve pathology
What are the 4 deep muscles of the posterior leg?
- tibialis posterior
- flexor digitorum longus
- flexor hallucis longus
- popliteus
What is the function of popliteus?
it functions in unlocking the extended knee
label the deep muscles of the posterior leg
What is the origin, insertion and action of tibialis posterior?
origin:
posterior tibia and fibula, interosseous membrane
insertion:
navicular and medial cuneiform bone
action:
- inversion of the foot
- plantarflexion of the ankle
What is the insertion, origin and action of flexor digitorum longus?
origin:
posterior tibia and fibula
insertion:
plantar surface, base of distal phalanges of digits 2-5
action:
flexion of digits 2-5
What is the origin, insertion and action of flexor hallucis longus?
origin:
posterior fibula and interosseous membrane
insertion:
plantar surface, base of distal phalanx of the big toe
action:
- flexes all the joints in the big toe
- plantarflexion of the ankle
How can the arrangement of the tendons of TP, FDL and FHL be remembered?
they all pass posterior to the medial malleolus
from the medial (closest to medial malleolus) to lateral:
Tom - TP is the most medial tendon, immediately behind the medial malleolus
Dick - FDL is lateral to the tendon of TP
Harry - FHL is lateral to the tendon of FDL
Which artery and nerve pass posterior to the medial malleolus?
How can this be remembered?
tibial nerve and posterior tibial artery
remember as Tom, Dick and nervous Harry
as the artery and nerve pass between the tendons of FDL and FHL
Where is the posterior tibial pulse palpable?
behind the medial malleolus
label the tendons of the ankle joint
Which paired deep veins accompany the arteries in the ankle joint?
Which larger vein to they drain into?
- anterior and posterior tibial veins
- fibular vein
They drain into the popliteal vein
What are the 2 muscles in the lateral compartment of the leg?
Where do their tendons pass?
- fibularis longus
- fibularis brevis
their tendons pass posterior to the lateral malleolus
label the muscles of the lateral compartment
Where is the common fibular nerve most vulnerable to injury?
as it enters the lateral compartment of the leg it winds around the neck of the fibula
it is most vulnerable to injury here
Where do the tendons of fibularis longus and fibularis brevis insert?
What is their innervation?
fibularis longus:
first metatarsal, medial cuneiform
fibularis brevis:
fifth metatarsal
innervation:
peroneal nerve (superficial fibular nerve)
What are the actions of fibularis brevis and fibularis longus?
plantarflexion of the ankle and eversion of the foot
Which vessels provide blood supply to the lateral compartment?
fibular (peroneal) artery
How might the fibula neck and common fibular nerve be injured?
What problem does this result in?
injured by fracture of the fibula or using a tight plaster cast
this results in foot drop - dorsiflexion of the foot is compromised and the foot drags during walking (plantarflexion)
What are the 2 movements present at the ankle joint and which compartments of the leg are repsonsible?
dorsiflexion:
- bringing the dorsum of the foot and toes upwards towards the leg
- performed by extensors in anterior compartment
plantarflexion:
- when the toes point to the floor
- performed by muscles in the posterior compartment
Which nerves innervate the dorsiflexors and plantarflexors?
the dorsiflexors in the anterior compartment are innervated by the deep fibular nerve
the plantarflexors in the posterior compartment are innervated by the tibial nerve
At which joint does inversion and eversion occur at?
the subtalar joint, NOT the ankle
What is the role of the ligaments of the ankle joint?
What happens if they become injured?
they are critical for stability
if they are injured, this may result in instability of the ankle joint
What causes a sprain of the lateral ligaments of the ankle?
What happens if the lateral ligaments are torn?
it is caused by forced inversion of the foot
e.g. falling over a kerb or step, walking or running on uneven ground or toppling over in heels
if the lateral ligaments are torn there will be pain, swelling and bruising along the lateral aspect of the foot and ankle
What may some severe inversion injuries lead to?
ligament injuries heal slowly and can destabilise the joint
inversion injuries may result in fracture of the lateral malleolus (distal fibula)
Which blood vessels supply the ankle joint?
the malleolar branches of the anterior tibial, posterior tibial and fibular arteries
if an ankle joint is dislocated, which 2 pulse points would be assessed?
if it was difficult to palpate the pulses, how could it be assessed if the foot was being adequately perfused?
dorsalis pedis and posterior tibialis pulses
if these are absent, it shows that the distal circulation has been compromised
ankle brachial index can also be used using a doppler and a blood pressure cuff
