· anatomically refers to talocalcaneal articulation
· surgeons often use ‘subtalar joint’ as functional term to include
· talocalcaneal part of anterior talocalcaneonavicular joint
· posterior talocalcaneal joint
· no muscular attachments
· made up of
· body
· neck and head
Body
Superior surface
· three articular surfaces for ankle mortise
· trochlea is articular upper surface for tibial plafond
· saddle-shaped
· convex from front to back and concave from side to side
· broad in front and narrow behind
· continued down each side for articulation with malleoli
· medial facet comma-shaped
· deep lamina of deltoid ligament attaches to smooth area behind medial articular surface
· lateral facet large and triangular
· lateral process at inferior apex
Posterior process
· projects behind trochlea
· divided into medial and lateral tubercles by vertical groove
· groove formed by tendon of FHL
· continuous with groove under sustentaculum tali
· lateral tubercle
· may form separate ossicle (in 50% - os trigonum)
· gives attachment to posterior talo-fibular ligament
· medial tubercle
· gives attachment to posterior fibres of superficial deltoid ligament
Inferior surface
· oblique concave articular facet
· for calcaneus (posterior facet)
Neck and head
Neck
· projects foward and medially
· grooved inferiorly to fit over calcaneal groove
· forms roof of sinus tarsi
· gives attachment to interosseous talocalcaneal ligament
· lateral neck
· gives attachment to cervical ligament
· gives attachment to anterior talo-fibular ligament
Head
· large articular surface facing forwards and downwards
· anterior articular surface
· for navicular
· inferior articular surface divided into three
· posterior part for sustentaculum tali (middle facet)
· anterior part for calcaneus (anterior facet)
· medial to these is articular surface for spring ligament
· made up of
· body
· sustentaculum tali
Body
Superior surface
· posterior third is rough surface behind tendo Achilles
· middle third is oval articular surface
· for talus (posterior facet)
· in front of posterior facet is oblique groove
· forms floor of sinus tarsi
· gives attachment to interosseous talocalcaneal ligament
· lateral facet gives attachment to cervical ligament
· gives attachment to bifurcate ligament
· gives origin to extensor digitorum brevis
· gives attachment to inferior extensor retinaculum
· anteromedially is articular surface
· for talus (anterior facet)
· may be continuous with articular surface of sustentaculum tali (middle facet)
Posterior surface
· smooth upper part
· for tendo Achilles
· convex lower part
· for plantar aponeurosis
Inferior surface
· posterior projection called tuberosity
· weight-bearing portion
· consists of two tubercles
· gives attachment to plantar aponeurosis
· large medial tubercle
· gives origin to abductor hallucis, flexor digitorum brevis and part of abductor digiti minimi
· smaller lateral tubercle
· gives origin to rest of abductor digiti minimi and lateral head of flexor accesorius
· surface is narrow anteriorly
· gives attachment to long plantar ligament
· tapers to anterior tubercle
· gives attachment to short plantar ligament
· anterior to tubercle is fossa
· corresponding fossa on posterior cuboid
· filled by short plantar ligament
Anterior surface
· for articulation with cuboid
Lateral surface
· peroneal trochlea
· oblique ridge
· peroneus brevis runs above
· peroneus longus runs below
· calcaneofibular ligament attaches to posterior part
Medial surface
· concave
· occupied by medial head of flexor accessorius
Sustentaculum tali
· medial prolongation of front half of upper surface
· carries medial facet superiorly
· grooved by tendon of FHL inferiorly
· medial border gives attachment to
· spring ligament anteriorly
· superior lamina of deltoid ligament posteriorly
· lies obliquely between anterior and middle, and posterior facets of subtalar joint
· formed by grooves in talus and calcaneus
· opens at lateral end like funnel
· canal occupied by limbs of interosseous talocalcaneal ligament
· are thickenings of adjacent joint capsules
· sinus closed by stem of inferior extensor retinaculum
· curved anteriorly like boat
Proximal surface
· concave articular surface
· for head of talus
Distal surface
· convex articular surface
· three triangular facets
· for cuneiform bones
Medial tuberosity
· gives attachment to tibialis posterior
· smooth area inferiorly
· for spring ligament
· wedge-shaped
· narrow laterally
Proximal surface
· two articular facets
· for fourth and fifth metatarsals
Distal surface
· articular surface
· for calcaneus
Medial surface
· articular surface
· for lateral cuneiform
· may articulate posteriorly with navicular
Inferolateral border
· deep groove
· for tendon of peroneus longus
· bridged by long plantar ligament
· posterior hollow
· for short plantar ligament
· properly called plantar calcaneocuboid ligament
· fills in adjacent hollows
· in front of anterior tubercle of calcaneum
· behind posterior ridge of cuboid
· attaches to both adjacent bony ridges
· covered by long plantar ligament
· covers plantar surface of calcaneus
· extends from posterior tuberosity to anterior tubercle
· attaches to cuboid
· deeper fibres attached to posterior ridge of cuboid
· superficial fibres attached to anterior ridge of cuboid
· thus bridges groove of cuboid
· forms fibrous roof over peroneus longus tendon
· covered by flexor accessorius
· seen between two heads of muscle
· arises from upper surface of calcaneus in lateral sinus tarsi
· two limbs
· medial limb
· attached to navicular
· articulates with head of talus
· forms part of talocalcaneonavicular joint
· lateral limb
· may be absent
· attached to cuboid
· is merely accessory ligament of calcaneocuboid joint
· properly called plantar calcaneonavicular ligament
· joins sustentaculum tali to inferior surface of navicular
· upper surface articulates with head of talus in talocalcaneonavicular joint
· attaches to adjacent surfaces of talus and calcaneus at lateral end of sinus tarsi
· is anatomical subtalar joint
· between
· posterior articular surfaces of calcaneus
· body of talus
· ball and socket joint
· ball formed by head of talus
· socket formed by
· navicular
· anterior body of calcaneum
· upper surface of sustentaculum tali
· spring ligament medially
· calcaneonavicular limb of bifurcate ligament laterally
· whole joint has single synovial cavity
· talocalcaneal part of joint forms anterior and middle facets of functional subtalar joint
· between calcaneus and cuboid
· three facets
· anterior and middle facets are talocalcaneal part of talocalcaneonavicular joint
· posterior facet is true subtalar (posterior talocalcaneal) joint
Anterior facet
· between inferior talar head and anterior part of body of calcaneum
Middle facet
· between inferior talar head and sustentaculum tali
Posterior facet
· between inferior body of talus and posterior part of body of calcaneum
· formed by
· talonavicular joint (part of talocalcaneonavicular joint)
· calcaneocuboid joint
· inversion and eversion occur at subtalar joint
· raising medial border of foot
· equivalent to supination
· accompanied by adduction of forefoot
· produced by tibialis anterior and posterior
· tibialis anterior produces dorsiflexion
· tibialis posterior produces plantarflexion
· together cancel out and produce inversion
· rasing lateral border of foot
· equivalent to pronation
· accompanied by abduction of forefoot
· produced by peroneal muscles
· peroneus longus and brevis are plantarflexors
· peroneus tertius is dorsiflexor
· together cancel out and produce eversion
· all muscles producing rotation attached anterior to midtarsal joint
· thus movement firstly occurs at midtarsal joint
· midtarsal joints wind up
· not much movement possible at them
· then transmit movement to subtalar joint via ligaments
· calcaneus and cuboid joined by long and short plantar ligaments
· thus rotatory force transmitted to calcaneus
· calcaneus rotates under talus
· talus wedged between malleoli and cannot invert and evert
· talus and calcaneus articulate at two separate joints
· axis of rotation occurs through centre of curvature of these joints
· axis passes
· from lateral tubercle of calcaneus
· upwards, forwards and slightly medially
· through neck of talus
· because axis is oblique
· inversion produces forefoot adduction
· eversion produces forefoot abduction
· foot stays pointing in desired direction
· inversion and eversion occur at subtalar joint
· adduction and abduction movements masked by reciprocal rotation at knee or hip