Bones of the Lower Leg

the lower leg composed of 2 bones

• tibia

• fibula

• aka the crural bones

tibia facts (4)

• medial side of lower leg

• bigger and stronger of the 2 bones

• weight bearing

• shaft is narrowest @ the junction of its middle and inferior 1/3

tibia AMAB

vertical direction

tibia AFAB

slightly oblique downward

tibia also has a

poor blood supply

tibia: proximal landmarks (5)

• tibia plateau

• medial and lateral facets

• intercondylar eminence

  • med and lat intercondylar tubercles

  • intercondylar fossa

• medial and lateral condyles

  • gerdy’s tubercle

• tibial tuberosity

tibial plateau structure (2)

• flat surface across top

• consists of 2 smooth surfaces (FACETs) that articulate with the large condyles of the femur

lateral facet (3)

• nearly circular

• concave from side to side

• convex @ posterior side

medial facet

oval, slightly concave from side to side

intercondylar eminence (3)

• lil mountain ranges

• tubercles: attachment point for the meniscus

• aka spine of tibia

tibial tuberosity (2)

• attachment for quad ms

• site for osgood-schlatters

tibia: shaft 3 borders

• anterior

• medial

• lateral (interosseous)

tibia: shaft 3 surfaces

• medial

• lateral

• posterior

tibia: anterior border

• most prominent

• runs from tibial tuberosity → medial malleolus

tibia: medial border

• runs from medial condyle → medial malleolus

• serves as attachment for ligs and ms

tibia: lateral border

• the interosseous crest

• begins at the fibular articular facet

tibia: medial surface

• b/w the anterior & medial borders

• pes anserine located in prox aspect

tibia: lateral surface

• b/w the anterior & lateral borders

• covered by the tendons of the extensors

tibia: posterior surface

• b/w the medial & lateral borders

• in the prox posterior portion = soleal line

tibia: distal landmarks (5)

• anterior surface

• posterior surface

• lateral surface

• medial surface

• inferior articular surface

tibia distal: anterior surface

• smooth

• attachment site for capsule of ankle joint

tibia distal: posterior surface

2 shallow grooves

• for tibialis posterior ms

• for flexor halluces longus ms

tibia distal: lateral surface

articulates w fibula at fibular notch

tibia distal: medial surface

• medial malleolus

• articulates w talus

• attachment for deltoid lig

tibia distal: inferior articular surface

• articulates w talus

• concave

fibula facts (4)

• lateral side of lower leg

• long and thin

• bears ~ 1/5th of ur BW

• does NOT articulate w knee joint

fibula landmarks (3)

• head

• lateral malleolus

• shaft

fibula proximal: head (3)

• 2cm below knee

• apex (styloid process) → upward elevation for lig/ms attachment

• articular facet → articulates w lateral condyle

fibula: neck fact

common fibular nerve spirals around here

fibula shaft: 4 borders

• anterolateral

• anteromedial

• posterolateral

• posteromedial

fibula shaft: 4 surfaces

• anterior

• posterior

• lateral

• medial

fibula shaft: anterolateral border

attachment for anterior intermuscular septum

fibula shaft: anteromedial border

• the interosseous crest

• attachment for the interosseous membrane

fibula shaft: posterolateral border

attachment for posterior intermuscular septum

fibula shaft: posteromedial border

• attachment for the transverse intermuscular septum

• becomes continuous with anteromedial border

fibula shaft: anterior surface

b/w the anterolateral and anteromedial borders

fibula shaft: posterior surface

b/w the posterolateral and posteromedial borders

fibula shaft: medial surface

b/w the anteromedial and posteromedial borders

fibula shaft: lateral surface

b/w the anterolateral and posterolateral borders

fibula distal: lateral malleolus (3)

• more prominent and post than medial malleolus

• medial surface has an articular facet that articulates w talus

• has roughening for lig attachment

malleolar fossa

depression below the facet for ligament attachment (lateral malleolus distal fibula)

the malleoli create a

mortise

patella structure (3)

• sesamoid bone within the quads femoris tendon

• flat, triangular bone

• articulates w patellar surface of the femur

patella function

better angle of pull for quads for powerful mvms

patella landmarks (5)

• base

• apex

• med and lat borders

• anterior surface

• posterior surface

patella base and apex

base = superior border

apex = inferior, pointed, attachment of ligamentum patella

patella: med and lat borders (3)

• thin

• attachment for med and lat retinaculum

• attachment of fibers of vast lat and vast med ms

patella: anterior surface (2)

• has longitudinal lines

• separated from skin by prepatellar bursa

patella: posterior surface (3)

• 6 articular surfaces

• divided into 2 facets by a vertical ridge (med and lat facets)

• each facet is divided by 2 horizontal ridges

functions of the patella cont. (4)

• principal insertion site of quadriceps femoris

• transmits forces generated by the quads femoris to the patella tendon

• diminishes forces at full ext

• inc the extension lever arm