Lower limb anatomy (Foot, ankle and rib/fib) Flashcards
tibia/fibula bones and muscles divided into three compartments:
Anterior
Lateral
Posterior
tibia
Larger and stronger than fibula
Weight-bearing
Triangular in cross-section, apex anterior
Numerous muscle attachments
Tibial condyles/plateau proximally
Distal tibia flattened (plafond) to articulate with talus
medial tubercle (malleolus)
fibula
Thinner and weaker than tibia
Non-weight-bearing
Important muscle attachment site, completely enclosed
Enlarged distal end (malleolus) longer than tibial malleolus
Tibia/fibula articulations
Form a bony ring
Proximal tibio-fibular joint (synovial)
Inter-osseous membrane:
fibrous connective tissue
Increases area for muscle attachment
Openings for nv vessels
Distal tibio-fibula joint
Fibrous joint (syndesmosis)
Thickening of membrane with anterior/posterior tibio-fibular ligaments
Integral to strength of ankle
Muscle compartments
Posterior:
Deep/superficial
Action:
Plantar-flex foot
Flex toes
Invert (medially rotate) foot
Achilles tendon
Lateral:
Peroneus longus/brevis
Evert (externally rotate) foot
Anterior compartment:
Four muscles
Action:
Dorsi-flex foot
Extend toes
Invert foot
Each enclosed by fascia and has own nv bundles; compartment syndrome
Foot
Equivalent to hand/wrist
Divided into:
Phalanges (14)
Metatarsals (5)
Tarsals (7)
Can also be divided as:
Forefoot
Midfoot
Hindfoot
Dorsal / plantar surfaces
Numerous and variable accessory ossicles
Phalanges/toes
Hallux and 2nd-5th toes
2 in hallux (great toe)
3 in other digits (proximal, middle, distal)
Each has BASE, shaft, head
Separated by interphalangeal joints
Metatarsals
Numbered 1-5
1st is shortest and strongest
2nd longest
Base, shaft, head/neck
Articulates distally at metatarso-phalangeal joints
Proximally at tarso-metatarsal (lisfranc) joints with adjacent metatarsals and tarsals
Sesamoid bones
Mid foot/distal tarsals
Navicular (boat)
Cuneiforms (wedge)
Medial
Intermediate
Lateral
Cuboid (cube)
hindfoot
Separated from mid foot (navicular/cuboid) by chopart joints
TaLUS (ankle) articulates with tibia/fibula
Calcaneum (HEEL)
Best visualised with ankle projections
calcaneum
short bone forms major weight-bearing portion of foot
Commonly fractured in falls from height
Multiple tuberosities / articular surfaces:
Calcaneal tuberosity and process
Anterior/posterior articular surface (sub-talar joint)
Sustentaculum tali (horizontal shelf of bone)
Anterior process
Peroneal (fibular) tubercle
talus
Formed of three parts:
head (distal)
Neck
Body
body articulates with tibia/fibula, almost entirely covered by hyaline cartilage (talar dome)
Inferior articular facets correspond with calcaneum facets to form sub-talar joint
Narrowing of neck forms tarsal sinus with calcaneal sulcus
Interesting features:
Majority covered in hyaline cartilage (60%)
No muscular/tendinous attachments
Prone to avascular necrosis in fractures due to arterial supply through neck
Fractures known as aviator’s
Ossification centres (Fore/midfoot
Phalanges:
Primary: diaphysis/shaft (9-15th week in utero)
Secondary: proximal epiphysis/base only (2-8years)
Fuse by 18 years
Metatarsal:
Primary: diaphysis/shaft (9-10th week in utero)
Secondary:
Base/proximal epiphysis hallux (3 years)
Heads/distal epiphysis 2-5th metatarsals (3-4 years)
Base 5th metatarsal apophysis
Fuse 17-20 years
Tarsals
Primary:
Calcaneum (3-4 month in utero)
Talus (6 month in utero)
Cuboid (9th week in utero)
Lateral cuneiform (1 year)
Medial cuneiform (2 years)
Intermediate cuneiform (3 years)
Ankle joint
Synovial saddle joint
Dorsi/plantar-flexion of the foot
Other movements through other joints
Referred to as the mortise joint
Formed by:
Tibial plafond superiorly
Lateral malleolus
Medial malleolus
Talar dome
Joint more stable with foot in dorsi-flexion (important in posistioning)
Ossification centres (ANKLE/HINDFOoT)
Distal Tibia:
Primary: diaphysis/shaft (7th week in utero)
Secondary Distal epiphysis/medial malleolus (1 year)
Fuses 15-17 years
Distal fibula:
Primary: diaphysis/shaft (8th week in utero)
Secondary Distal epiphysis/medial malleolus (1 year)
Fuses 17-19 years
Secondary:
Calcaneum:
posterior surface (6-8 years).
Fuses at puberty
Talus:
occasionally has posterior process
os trigonum if un-united by maturity
Normal variant
Ankle joint
Surrounded by synovial membrane and fibrous capsule
Ligamentous structures provide large amount of strength/stability
Generally named by structures they connect
Tibio-fibular syndesmosis
Medial (deltoid)
fan-shaped
4 parts
Lateral
3 parts
Bony ring theory; injuries often a combination of bony/soft tissue abnormalities
Think about forces involved
Inter-tarsal joints
Remaining movements produced by smaller joint in the midfoot:
Inversion / eversion
Supination/pronation
Predominantly of:
Sub-talar
Talocalcaneonavicular
Calcaneocuboid
Synovial, supported by extensive ligamentous complex
Other joints
Tarso-metatarsal (TMT)
Lisfranc joints / ligaments
Synovial plane joints
Sliding movement to allow pronation/supination
Greatest of 1st tmt joint
Metatarso-phalangeal (MTPJ)
Synovial ellipsoid
Flexion/extension
Some other movements
Supported by ligament complex
Interphalangeal joints
Hinge
Flexion/extension
Arches of the foot
Help to distribute great forces on the foot
Longitudinal arch
Calcaneum to metatarsal heads
Most pronounced medially
Supported by plantar fascia/aponeurosis
Transverse arch
Supported by soft tissue anatomy
Foot problems intrinsically linked to biomechanics of the anatomy; wide range of causes
musculature
Extensive and complex (especially plantar surface), major components include:
Intrinsic (arise in foot)
Extrinsic (arise in leg)
Extensors (dorsal)
Flexors (Plantar)
Neurovascular supply
Supplied either:
Dorsally alongside extensor tendons
Anterior tibial/dorsalis pedis artery
Fibular nerves
great saphenous vein
Through tarsal tunnel medially
Posterior to medial malleolus
Posterior tibial artery (can palpate pulse)
Tibial nerve
Small saphenous vein
