Structure and Function of Ankle and Foot

how much weight does the fibula carry

10% of body weight

distal end of the tibia is slightly what?

externally rotates (20-30 degrees)

proximal tibiofibular joint

synovial, planar

Articulating facets on tibia/fibula are largely flat,

distal tibiofibular joint

fibrous and syndesmosis

concave tibia

convex fibula

Both proximal and distal joints allow for what?

Allow fibula to slide superior/inferior with some rotation; fibula moves superior with ankle dorsiflexion

resting position for tibiofibular joints

plantarflexion

closed pack position for tibiofibular joints

dorsiflexion

rearfoot

connections of the talus to tibia/fibula or the talus to the calcaneus

DF and PF occurs mainly in what joint and plane?

talocrual joint sagittal plane

eversion and inversion occurs mainly in what joint and plane?

mainly subtalar and transverse tarsal joint

frontal plane

adduction and abduction occur in what jointand what plane?

mainly subtalar and transverse tarsal joint

Transverse plane

inferior tibia-fibula surfaces

medial, lateral and trochlear facet

Which way is the trochlea wider in the talus and why?

anteriorly wider, this is why there is more space during plantar flexion for the talus to move (decreasing stability) think high-heels--> no stability

Increases stability in dorsiflexion

deltoid ligament resists

talar eversion

abduction of the foot

anterior/posterior talus displacement (very rare to see this ligament injured)

lateral collateral ligament resists

talar inversion

anterior/posterior talus displacement

ATFL

resists plantarflexion with inversion

anterior talar displacement, foot add

(most commonly injured ligament)

CFL

resists inversion with DF

PTFL

stabilizes talus in crura, resists posterior talar displacement, foot abduction

talocrual axis of motion

oblique

Medial: anterior and superior

Lateral: posterior and inferior

(use malleoli for reference)

what does the talocrual axis of motion (oblique) allow for in addition to flexion/extension

DF/EV

PF/INV

Normal ROM for talocrual joint

20 degrees DF

50 degrees PF

ROM for gait on a level surface

10 degrees DF

15-20 degrees PF

open chain dorsiflexion

anterior roll and posterior glide

open chain plantarflexion

posterior roll and anterior glide

closed chain dorsiflexion

anterior roll and glide

closed chain plantarflexion

posterior roll and glide

anterior compartment of leg

tibialis anterior, extensor digitorum longus, extensor hallucis longus, fibularis tertius

lateral compartment of leg

fibularis longus and fibularis brevis

posterior compartment of leg

gastrocnemius, soleus, plantaris, tibialis posterior, flexor digitorum longus, flexor hallucis longus, popliteus

subtalar joint function

converts rotation forces of the tibia to the foot

shock absorbtion

accomodate rear foot to the ground

subtalar joint ligament support

cervical ligament

lateral collateral and deltoid ligaments of the talocrual joint

interossseous ligament

sinus tarsi

opening in the middle of the subtalar joint, common location of pain and swelling

subtalar joint axis

diagonal, motion around one, ablique axis that occurs through all three planes

subtalar joint supination open chain

calcaneus moving on talus

inversion, adduction and plantarflexion

most visible is inversion

supination is the closed packed position

subtalar joint pronation open chain

calcaneus moving on talus

eversion, abduction, dorsiflexion

most visible is eversion

pronation is the loose packed position

subtalar joint supination closed chain

talus, calcaneus and tibia move

calcaneus inverts

subtalar joint pronation closed chain

talus calcaneus and tibia move

calcaneus everts

does pronation lock or unlock

unlocks the foot making it an absorber of shock and allows accommodation of the foot to the ground (loose packed position)

does supination lock or unlock?

looks the foot is making a rigid lever for propulsion of the body forward (close packed position)

rest position of the foot

midway between supination and pronation