Lecture 14 & 15 - The Knee Flashcards
what actions are possible at the knee
flexion and extension
- > flexion/extension direction is reversed
important structures of the femur
important at the distal end of the femur
important structures of the leg bones
features of the tibia
- > medial bone in crural region
proximal features
- > has a medial and lateral condyle which are smooth surfaces for articulation with femur
- > has fibular articular facet which is an articulation site for head of fibula under lateral condyle
tibial tuberosity
rough anterior projection inferior to the condyles
- > can be palpated just inferior to the patella
- > for attachment of patellar ligament
features of fibula
- > long thin lateral crural bone
- > non weight bearing
- > has prox. head with flat articular facet for articulation with the tibia
- > narrow neck and slender shaft
- > distal end expands into lateral malleolus
why do we have a fibula if it’s not weight bearing?
- Provides a site for muscle attachments
- It provides lateral stability to the ankle joint
- With the tibia, the fibula has an interosseous membrane (site for muscle attachment)
what is the purpose of the patella
act as a pully to redirect the forces for the quad tendon
muscles involved in knee flexion
- > hamstrings
- > gastrocnemius
- > sartorius
- > gracillis
muscles involved in knee extension
quadriceps femoris (group of 4 muscles)
- > rectus femoris
- > vastus lateralis
- > vastus intermedius
- > vastus medialis
what muscle “unlocks” the knee joint
popliteus
OINA of popliteus
Origin
- > lat femoral condyle
Insertion
- > post surface of the tibial, proximal to the soleus line
Nerve
- > tibial nerve
Action
- > medially rotates the tibia relative to the femur when knee is flexed
- > unlocks the knee to allow flexion
- > helps prevent ant dislocation
quadriceps
don’t forget gracillis
OINA of rectus femoris
Origin
- > anterior inferior iliac spine
Insertion
tibial tuberosity (via patellar tendon)
Nerve
- > femoral
Action
- > flexes hip and extends knee
OINA of vastus lateralis
Origin
- > greater trochanter and lateral lip of linea aspera
Insertion
- > tibial tuberosity via patellar tendon
Nerve
- > femoral
Action
- > extends knee
OINA of vastus medialis
Origin
- > intertrochanteric line and medial lip of the linea aspera
Insertion
- > tibial tuberosity via patellar tendon
Nerve
- > femoral nerve
Action
- > extends knee
OINA of vastus intermedius
Origin
- > anterior and lateral surfaces of the shaft of the femur
Insertion
- > tibial tuberosity via patellar tendon
Nerve
- > femoral nerve
Action
- > extends the knee
OINA of sartorius
Origin
- > anterior superior iliac spine
Insertion
- > pes anserinus
Nerve
- > femoral
Action
- > tailors position, longest muscle in the body
- > flexes hip and knee, abducts and externally rotates hip
OINA of the gracilis
Origin
- > ischiopubic ramus
Insertion
- > pes anserinus
Nerve
- > obturator
Action
- > flexes, medially rotates and adducts the hip
OINA of the gastrocnemius
Origin
- > lat head: lateral aspect of the lateral condyle of the femur
- > med head: popliteal surface of the femur superior to the medial condyle
Insertion
- > post surface of the calcaneus via the calcaneal tendon (achilles)
Innervation
- > tibial nerve
Action
- > plantar flexes the ankle when the knee is extended
- > raises heel during walking
- > flexes knee
O/I/I/A of bicep femoris
Origin
- > Long head: ischial tuberosity
- > Short head: linea aspera of the femur
Insertion
- > head of fibula
Nerve
- > LH fibial nerve
- > SH common fibular nerve
Action
- > both heads flex and extend the knee but only LH extends the hip
O/I/I/A of semitendinosus
Origin
- > ischial tuberosity
Insertion
- > Pes anserinun (tibia)
Nerve
- > sciatic nerve (tibial)
Action
- > flex knee and extends hip
O/I/I/A of semimembranosus
Origin
- > ischial tuberosity
Insertion
- > medial condyle of the tibia
Nerve
- > sciatic nerve (tibial)
Action
- > flex knee extends hip
knee joint characteristics
synovial hinge joint between femur, tibia and patella
- > largest and most complex joint in the body
ligaments of the knee
- > patellar lig
- > fibular (Lateral) collateral lig
- > tibial (medial) collateral lig
- > ant (ACL) and post (PCL) cruciate ligs
- > transerve lig
tibiofemoral joints
Menisci
- > comprised of fibrocartilage
- > wedge shaped with greater thickness in the periphery
- > blood supply to the periphery but not to inner portions
- which doesn’t allow for healing*
functions of menisci
- > enhance stability
- > shock absorption
- > enhances lubrication of the joint
- > limits movement between tibia and femur
injured meniscus
MCL
medial collateral ligament
- > covers most medial side of knee joint
- > protects against medial movement (imposed from a force on the lateral side
ligaments tears/ how do we test MCL injury
valgus stress test
LCL
lateral collateral ligament
- > thinner than MCL
- > protects agains lateral movement (imposed from a force on the medial side)
ACL
anterior cruciate ligament
- > provides the primary (85%) restraint for anterior movement of the tibia
- > tight when knee is in an extended position
how to test the ACL
anterior drawer test
- > put fingers on patella and pull a 90deg flex knee
- > if it pulls out then its torn
PCL
posterior cruciate ligament
- > provides primary (95%) of restrained to posterior movement of the tibia on the femur
- > taut in full knee extension
types of ACL injuries
non contact and contact injuries
why do ACL injuries occur more in females
- > increased Q angle due to pelvis shape
movements of the tibiofemoral joint
Flex/Extend
- > 130-145deg
Hyperextension
- > 1-2deg
Internal rotation
- > 6-30deg
External rotation
- > 45deg
*through 90deg flexion, no rotation when in locked position
movements of the patelofemoral joint
Extension of the knee (resting position)
- > rests higher on femur between medial and lateral condyles
Flexion at the knee
- > patella moves inferiorly and towards the lateral condyle of femur
popliteal fossa
edges defined by the…
- > semimembranosus (sup and med)
- > bicep femoris (sup and lat)
- > two portions of gastrocnemius (inf and med/lat)
*lat head of gastro and the plantaris muscle (inf and lat)
sciatic nerve
a bundle of 2 nerves
- > tibial n
- > common fibular n
- the nerve splits in the popliteal fossa*
vein that passes through the popliteal fossa
- > small saphenous vein
- > harvested to be used in some heart surguries
contents of the popliteal fossa
- > tibial nerve
- > common fibular nerve
- > popliteal vein
- > small saphenous vein
- > popliteal artery
