Functional Anatomy - Knee Flashcards
tibiofemoral kinematics
Convex vs Concave rules
convex (m): femur
- roll and slide in opposite directions
concave (f): tibia
- roll and slide in same direction
Screw-home mechanism
Describe the locking mechanism at the knee joint and explain its functional significance
- Rotation of the tibia and femur of the last 20º of knee extension
- Bc medial femoral condyle is larger
- Femur rotate medially when weight bearing
- Tibia rotate lateral when non-weight bearing
- Causing knee locking (greatest congruency) to allow to stand passively
Screw-home mechanism
What is the movement between the tibia and femur during terminal knee extension?
- Femur rotate medially when weight bearing
- Tibia rotate lateral when non-weight bearing
Screw-home mechanism
What is the reason for femoral medial condyle rotating medially ?
- bc femoral M condyle bigger than L
- then allow for rotation
- due to Increase congruency
non-weightbearing
With a fixed femur, in which direction does the tibia move?
Screw-home mechanism
- Laterally
weightbearing
With a fixed tibia, in which direction does the femur move?
Screw-home mechanism
- Medially
Screw-home mechanism
What happens to the ACL and PCL?
- crosses to “lock” the knee
- ACL and PCl are taut
Screw-home mechanism
How do we “unlock the knee”?
- Popliteus
- Laterally rotate femur to unlock the knee
Screw-home mechanism
Why do we lock the knee?
- Passive stability
Synovial joints
Roll then slide
2 bones stay together
max ROM
Screw Home mechanism
What
Why
Results in
what:
- rot bw tib and femur during terminal knee ext (last 20º)
- “spin”
why:
- bc med fem cond = larger
results in..
- knee-locking
spin, roll, slide
Knee flexion
tibia: (f) concave
eg. standing w knee @ 90º
- rolls post
- slide post
femur: (m) convex
eg. downwards phase of a squat
- rolls post
- slides ant
spin, roll, slide
Knee extension
tibia: (f) concave
eg. standing w knee at 90º and extending knee out
- rolls ant
- slide ant
femur: (m) convex
eg. coming up from a squat
- rolls ant
- slides post
Patellofemoral kinematics
Full knee extension
- patella X in contact w pat surf of femur
- 0º flexion
- DCR stability
Patellofemoral kinematics
Knee flexion
- as º of flexion INCR’s
contact area of:
a) patella: moves proximally
b) femur: moves posteriorly
Tibiofemoral stability
Static (passive / non-contractile)
Dynamic (active / contractile)
Static:
- meniscus
- ligaments
Dynamic:
- quad fem (vastus med, lat, intermed, rec fem)
- pes anserinus
- ITB (has musc that attach into it)
Tibiofemoral stability
Static - meniscus
structure and function
structure:
- fibrocart discs bw condyles
function:
- absorb shock
- distrib WB forces
- INCR congurency bw condyles
- assist w lubric -> distr syn fluid w in knee joint cavity
TIbiofemoral stability
Static - meniscus
attachments
Lateral:
- PCL
Medial:
- MCL
Tibiofemoral stability
Static - ligaments
- ant tib disp
- post tib disp
- add stab
- abd stab
- int tib rot stab
- ext tib rot stab
1. ant tib disp:
P: ACL
S: MCL, ITB
2. post tib disp:
P: PCL
S: MCL, LCL, oblique pop lig
3. add stab:
P: MCL
S: ACL, PCL, post oblique lig
4. abd stab:
P:
S: LCL, acruate pop lig
5. int tib rot stab:
P: MCL, oblique pop lig, post oblique lig
S: ACL, PCL
6. ext tib rot stab:
P: LCL, acruate pop lig
S: ACL, PCL
tibiofemoral stability
Dynamic - quadraceps femoris
action and function
action:
- knee ext
- last 15ºDCR mech adv
function:
- stabilise patella
tibiofemorall stabilty
Dynamic - Quad fem:
vastus medialis
Vastus medialis - functions
VML:
- knee extensor
VMO:
- stablises patella medially
- prev lat dislocation of pat from VL
- realigns pull -> INCR effic of quads
- prev lat tracking dur patella ext
tibiofemoral stability
ITB
structure and function
structure:
- thickening of feep fascia of thigh
- consistently taut
function:
- stablise pat laterally
- assist ACL -> prev ant tib slide
during flexion -> behind knee axis
during extension -> infront knee axis
tibiofemoral stability
pes anserinus
structure and function
function:
- knee flexion
- int rotation
- stabilise ag. valgus stress
1. sartorius
2. gracilis
3. semitendinosus
“say grace before tea”
Tibiofibular joints
3 types
- prox tibiofib joint
- mid tibiofib joint
- dist tibiofib joint (syndesmosis)
tibiofibular joints
prox VS dist and med
proximal:
- synovial, plane
- move fibula during planatrflex and dorsiflex
distal and medial:
- fibrous syndesmosis
- maintain inregr of malleolus mortise
tibofibular joint
- prox TF joint
class, A/S, movement
class:
- syn, multi, plane
A/S:
- head of fibula
- fibula articular facet of tibia
movement:
- small gliding
tibiofemoral joints
medial and distal TF joints (syndesmosis)
class, s, movement
MEDIAL
class:
- fibrosus, syndesmosis
s:
- interosus membrane
movement:
- slight movem bc of long fibres
DISTAL:
class:
- fibr, syndesmosis
A/S:
- fibular notch of tibia
- dist fibula
tibiofibular joints
Ligaments:
A-PTFL
P-PTFL
IOL
TL
Anterior Proximal Tibiofibular Ligament (A-PTFL):
- proximal tibia to the fibula.
Posterior Proximal Tibiofibular Ligament (P-PTFL):
- proximal tibia to the fibula.
Interosseous Ligament (IOL): - - contin of inter mebr (bw tib + fib) INCR’s stab
(inf) Transverse Ligament (TL):
- distal tibia and fibula at the distal end.
Ankle (talocrural) joint
Talocrural joint
Classification, movements, articular surfaces, joint caspule
class:
- syn, uniaxial, hinge
movements:
- plantar (50º), dosri (30º)
articular surfaces:
- tibia -> trochlea surface
- tib + fibula -> malleolar surfaces of tib + fib
- talus -> trochelar surface = WB
joint capsule:
- weak/think ant + post so dosriflex/plantarflex can occur
Ankle (talocrural) joint
Ligaments - medial
M collateral ligs, calcaneofibula, i/o talocalc, plantar calcnav
medial collateral lig🔺
1. tibionavic lig - DCR abd
2. A tibiotalar lig - DCR plantar
3. P tibiotalar lig - DCR dors-
4. calcaneofibular - DCR inversoin, dorsi
5. interosseous talocancalcaneal - INCR joint stab
6. plantar calcaneonavicular - support M longitudinal foot arch
Talocrural Joints
- subtalar
- transverse (mid) tarsal joint:
talocalcaneonavicular
calcaneocuboid - tarsometatarsal joints (TMT)
- metatarsophalangeal joints (MTP)
- interphalangeal joints (IP)
movements, function, classification
class:
- synovial, plane, multiaxial
movements:
- inversion: sole inwards (iPADS)
- eversion: sole outwards
function:
- adjust to uneven surfaces
- efficency in gait
Subtalar joint
Subtalar joint - articular surfaces
syn, multi, plane
- post articular facet of inf surf of talus (f)
- post articualr facet of sup surf of calc (m)
Transverse tarsal joint
Talocalcaneonavicular joint - articular surfaces
synovial, multiax, B/S
- artic facet on head/neck talus
- ant + mid facets on sup surf of calc
- post artic facet of navic
- plantar calcnav lig
Transverse tarsal joint
LaTeral and plantar ligaments
A/P talofib, calcfib, calccuboid short + long
- A talofibular - DCR plantar
- P talofibular - DCR dorsi
- calcaneofibula - DCR dorsi + add
- short calcaneocuboid lig - foot longitud arch
- long calcaneocuboid lig - foot longitud arch
calcaneocubital joint
calcaneocubital joint - articular surfaces
syn, multi ax, plane
articular facet of ant calc
articular facet of post cub
tarsometatarsal joints
tarsometatarsal joints
class, movem, articular surf
class:
- syn, plane, multi
movements:
- flex/ext
- 1st joint = slight abd / rot (support balance uneven gorund)
articular surfaces:
1. med cub -> B1stM
2. intermde cub -> B2ndM (recessed / least mobile)
3. lateral cub -> B3rdM
4. lateral cub -> cuboid + B4thM
5. cuboid + B5thM
tarsometatarsal joints
tarsometatarsal joints - ligaments
dorsal TML, plantar TML, cuneometatars inteross lig
functions
1. dorsal TML:
- DCR flex meta
2. plantar TML:
- DCR ext meta
3. cuneometatarsal interossus lig:
- 3 slips: med + lat cuneiforms
- 2 slips: B2nd + 4th metatarsals
interphalangeal joints
interphalangeal joints
class, movem, A/S
class:
- syn, uniax, hinge
movements:
- flex/ext
A/S:
- head of phalanx
- bases of adj phalanx
interphalangeal joints
interphalangeal joints - ligaments
collateral, plantar
1. collateral ligament:
s: thick articular capsule on side
f: DCR flex digits
2. plantar ligs:
s: fibrocart plates
grooved for long flexor tendons
f: DCR ext
metatarsophalangeal joints
metatarsophalangeal joints
class, A/S, movement of digits
class:
- syn, biax, condyloid
A/S:
- head of metatarsals
- base of prox phallanges
movement of digits:
- flex/ext
- abd/add
- circumduction
metatarsophalangeal joints
metatarsophalangeal joints - ligaments
collateral lig, plantar lig, deep t/verse metatars lig
1. collateral lig:
s: thickenings of articular capsle on sides
f: DCR flex of digits
CDR abd/add of digits in flex
2. Plantar lig:
s: fibrcart
grooved for long flexor tendon
f: DCR ext of digits
3. deep transverse metatarsals lig
attach: connect plantar lig of MTP joints
f: keep heads of metatarsals togther -> assist w WB
