tarsometatarsal joints

Osteology

cuneiform bones

· all three are wedge-shaped

· medial has sharp edge up

· middle and lateral have broad base up

· articulate

· anteriorly with 1st, 2nd and 3rd metatarsal bases

· posteriorly with navicular

· with each other and cuboid

· medial cuneiform articulates with 1st MT by separate synovial cavity

· other 4 MTs articulate with middle and lateral cuneiforms and cuboid by common joint space

· extends back into joint between cuneiforms and navicular

· joints between cuneiforms and with cuboid all toward dorsal surface

· plantar surface occupied by attachments of plantar interosseous ligaments

· middle cuneiform shorter than other 2

· 2nd MT base mortised between medial and lateral cuneiforms

Medial cuneiform

Medial surface

· has small facet for insertion of tibialis anterior

· primary insertion for TA

Inferior surface

· tubercle at anterior angle for attachment of peroneus longus

metatarsals

1st MT

Proximal end

· kidney-shaped facet for medial cuneiform

· lateral facet for 2nd MT base

· inferior smooth fossa for peroneus longus

· primary insertion of PL

· medial smooth fossa for tibialis anterior

Distal end

· distal articular surface

· extends onto plantar surface

· 2 plantar grooves for sesamoids

2nd to 4th MTs

· 2nd base in mortise (short middle cuneiform)

· heads united by transverse ligaments

5th MT

· base prominent laterally

· tuberosity for insertion of PB

· dorsal surface receives PT

phalanges

Hallux

· EHB inserts into base of proximal phalanx

· EHL inserts into base of distal phalanx

· FHB inserts into base of proximal phalanx via sesamoids

· FHL inserts into base of distal phalanx

Lesser toes

· as in hand

Arthrology

· 1st TMT jt has own capsule and synovial membrane

· some vertical movement possible

· 2nd TMT jt rigid

Arches

medial longitudinal arch

Components

· consists of

· calcaneus

· talus

· navicular

· 3 cuneiforms

· medial 3 MTs

· pillars are

· tuberosity of calcaneus

· heads of medial 3 MTs

Maintenance

Bony

· no bony factors

· head of talus supported on sustentaculum tali is negligible

Ligaments

· static support

· important not sufficient alone

Plantar aponeurosis

· most important

· draws pillars together

· shortened by extension of toes

Spring ligament

· supports head of talus

Interosseous ligaments

· esp. talocalcaneal

Muscles

· dynamic support

· during takeoff and landing

FHL

· very important

· acts as bowstring

· from sustentaculum tali

· to medial 3 digits

· pulls pillars together

Short muscles

· AbH and medial FDB

· some role

Sling of TA and PL

· both inserted into medial cuneiform and base of 1st MT

· but exert opposite effects

· TA slightly elevates arch

· PL depresses arch

Invertors

· TA and TP

· raise medial border of foot from ground

Lateral longitudinal arch

· much flatter than medial

Components

· consists of

· calcaneus

· cuboid

· lateral 2 MTs

Maintenance

Bone

· no bony factor

Ligaments

· of some importance

· plantar aponeurosis

· short plantar ligament

· long plantar ligament

Muscles

· most important

· peroneus longus pulls up on arch

· FDL to 4th and 5th toes

· lateral FDB and AbDM