Knee Flashcards
What is different about the lateral condyle of the inferior femur?
Projects farther laterally
how does the lateral condyle of the femur assist in functionality?
Patellofemoral stability
How does the medial condyle of the femur assist in function?
Screw home mechanism
What creates the extension of the lateral condyle of the femur?
Lateral pull of patella by muscles
Which condyle of the tibia is 50% larger?
Medial
What are the 3 facets of the patella?
Medial, lateral, odd
What do the medial and lateral facets of the patella form in the trochlear groove?
“V”
What are the 2 articulations of the Knee?
- Tibiofemoral
2. Patellofemoral
What is 1 limitation and 1 functional advantage of the tibiofemoral joint?
Limitation: Poor congruence
Advantage: Large articular surface
What is an advantage of the patellofemoral joint over the tibiofemoral joint?
Good congruence
When is the congruence better in the patellofemoral joint?
In flexion
What is the fibrous sleeve that invests the distal end on the femur and the proximal tibia?
Joint Capsule
What is the inner surface of the joint capsule covered by?
Synovial lining
What reinforces the joint capsule?
Ligaments for stability
In extension, the joint capsule is loose ________ and tight ________ preventing ________.
Anteriorly, Posteriorly, Hyperextension
In flexion, _________ aspect of capsule prevents femur from _______ _______
anterior, sliding, anteriorly
Are the ACL & PCL within the synovium?
NO
Where is the synovium found?
Lines joint capsule
What does the synovium do posteriorly?
Invaginates
Why do the ACL & PCL need their own blood supplies while the menisci do not?
ACL & PCL are not within the synovium
What are 2 functions of the Bursae?
- Reduce friction
2. Increase surface area (reduce compressional stress)
What are the 4 anterior bursae? (Superior to inferior)
- Suprapatellar bursa
- Prepatellar bursa
- Depp infrapatellar bursa
- Subcutaneous infrapatellar bursa
Where are the posterior bursae located?
Under muscle bellies and tendon attachments
What are 3 areas posterior bursae are found?
- Gastroc
- Popliteus
- Semimembranosis tendon
Which menisci have insertion sites that are far apart? (C-shaped)
Medial
Which Menisci have insertion sites that are close together? (Circular)
Lateral
What ligament has capsular attachments on the Medial Menisci?
MCL
What ligaments attach to the lateral menisci posteriorly?
Meniscofemoral (PCL)
What are the 4 ligaments about the Menisci?
- Coronary
- Transverse
- Intercondylar
- Meniscofemoral
Where do the coronary ligaments attach?
Menisci -> Tibia
Where do the transverse ligaments attach?
Anterior menisus -> anterior meniscus
Where do the intercondylar ligaments attach?
Meniscal horns -> intercondylar eminence
Where do the meniscofemoral ligaments attach?
Posterior horn of lateral meniscus -> medial femoral condyle
What are 3 functions of the Menisci?
- Improve congruency
- Assist in arthrokinematics
- Distribute weight bearing forces
How do the menisci influence loading?
Greatly reduce external forces by increasing surface area.
What is needed of the menisci during tibiofemoral motion to improve congruency and distribute forces?
Movement
During flexion, menisci move _______
Posteriorly
During extension, menisci move _________
Anteriorly
Which menisci has twice as much motion?
Lateral
Which menisci are attached to the joint capsule?
Medial
What 4 structures does the stability of the knee depend on?
- Collateral Ligaments
- Cruciate Ligaments
- Capsular Ligaments
- Muscles/tendons
What structure increases the surface area of the knee extensor mechanism?
Patellar Retinacula
How would medial external force affect the knee?
load the lateral side (varus)
How would lateral external force affect the knee joint?
Medial loading (valgus)
Which type of loading (Valgus or varus) is more common?
Valgus
Which cruciate ligament is ccapsular?
MCL
Which cruciate ligament is Extrinsic?
LCL
When is the MCL most effective?
Extension (taut in this position)
What muscle attachment does the LCL run underneath?
Biceps femoris
What does the LCL primarily resist?
Varus Stress
What does the MCL primarily resist?
Valgus stress
What are 2 secondary restraints of the LCL?
- Tibial Lateral Rotation
2. Posterior tibial displacement
slide 38
slide 38
Which condyle of the femur extends farther distally and laterally?
Medial
What forms the Iliotibial Band proximally?
Fascia investing TFL & glut max
Where does the IT band insert?
Lateral Tibial Condyle
Which side of the knee does the IT band reinforce
Lateral
How does the IT band assist the ACL?
Resists tibial IR and posterior displacement of the femur when tibia is fixed.
What are the Posterior reinforcing ligaments of the knee
- Oblique Popliteal
2. Arcuate
What are the proximal and distal attachment sites of the oblique popliteal ligament?
Proximal: Lat condyle of femur
Distal: Med Condyle tibia
What are the Proximal and distal Attachment sites of the Arcuate ligament?
Proximal: Lat condyles of femur and tibia
Distal: head of fibula
The cruciates are within the _________ _________ but outside of the _________ ___________
- Articular Capsule
2. Synovial Capsule
The Cruciates are stabilizing ligaments that resist ________ and anterior/posterior ________ of the tibia
- Rotation
2. Translation
What are the attachments of the ACL?
Lateral Femoral condyle -> Anterior intercondylar fossa
What innervates the ACL?
Tibial Nerve
What two forces does the ACL primarily resist?
Anterior tibial Translation & Internal Tibial Rotation
The ACL secondarily resists ______ and _______ stresses
Varus and valgus
What are the attachment sites of the PCL?
Medial femoral condyle -> posterior intercondylar fossa
What are the attachment sites of the meniscofemoral ligaments?
posterior horn of lateral meniscus -> lateral wall of medial femoral condyle
What does the PCL primarily resist?
Posterior translation of tibia or anterior translation of femur
At what range of flexion is the PCL least effective at?
70-90
What is the Screw-home mechanism?
Femur rotates medially in relation to the tibia or vice versa upon extension: locking/unlocking the knee
Which segment (femur or tibia) moves in the screw-home motion?
Whichever has least amount of inertia.
What muscle works to unlock/lock the knee?
Popliteaus
What is the average angle of the patellar facet angle?
138 degrees
What is an incomplete fusion of the epiphyseal disc in the patella?
Bipartite Patella
What is the Patella embedded in?
Quad Tendon
What does the patella articulate with?
Trochlear groove of femur
How do the muscles typically pull the patella?
Along Diaphesis of femur
What does the Q Angle measure
line from ASIS (femoral shaft) to center of patella
Line from tibial tuberosity to patella
Know how to draw the Q-angle
Draw it.
What is the function of the patella?
Provides mechanical advantage by placing torque further from the axis of rotation
Draw PFJ
DRAW IT
What is a high-riding patella called?
Patella Alta
What is the normal patella ligament hight / patellar height ratio
Should be bout 1.3/1
What happens fuctionally when the patella rides high on the femur?
Less congruence and stability
at what angle of flexion does the patellar tendon compress the anterior portion of the patella?
90degree
at what angle of flexion does the patellar tendon compress the middle portion of the patella?
45deg
at what angle of flexion does the patellar tendon compress the Posterior portion of the patella?
20Deg
at greater flexion angles, quad tendon contacts ______
femur
What are the only anterior muscles that control extension?
Quads
Vastus Intermedius prox Origin
Anterior femoral shaft
Vastus lateralis Prox Origin
Lateral Lip of Linea Aspera (Lat Greater trochanter)
Vastus Medialis prox origin
Med lip of linea aspera (distal intertrochanteric line)
All Vasti Distal ins
Tibial Tuberosity (via patellar ligament)
Vasti Muscles innervation
Femoral N
functions of Vasti Muscles
- Extend Knee
2. Prevent entrapment of capsule
Rectus Femoris Prox Origin
AIIS and Sup (roof) acetabulum
Rectus Femoris Dist Ins
Tibial tuberoosity (via patellar ligament)
Rectus Femoris Innervation
Femoral N
Functions of Rectus Femoris
- Extends Knee
2. Flexes Hip
All Hamstring muscles Prox origin
Ischial Tuberosity
biceps Femoris long head dist ins
Head of fibula
Semimembranosis dist ins
Medial Tibial Condyle
Semitendinosus dist ins
Pes Anserinus
Innervation of all hamstrings (except biceps femoris short head)
Tbial N
Function of all Hamstrings (except biceps Femoris, short head)
- Flex Knee
- IR Tibia (semimem & semitend)
- ER Tibia (BF long head)
- Extend hip
Biceps femoris short head prox orig
Linea Aspera (lateral lib in middle 1/3 of femur)
Biceps femoris short head dist ins
Head of fibula
Innervation of Biceps Femoris short head
Common Fibular N
What are the functions of the biceps femoris short head?
- Flexes Knee
2. ER Tibia
Popliteus Prox origin
Lateral Femoral Condyle
Popliteus Dist ins
Posterior Tibial Surface
Popliteus Innervation
Tibial N
Functions of Popliteus
- Flexes Knee
- IR Tibia
- ER Femur
- Limits Hyperextension
Sartorius Prox Origin
ASIS
Sartorius Dist Ins
Medial Tibial Condyle (pes anserinus)
Sartorius Innervation
Femoral N
Functions of Sartorius
- Flexes Knee
- Flexes Hip
- Abducts Hip
- ER Hip
Gracilis Prox Origin
Inferior Pubic Ramus
Gracilis Dist Ins
Medial to the tibial Tuberosity (pes anserinus)
Gracilis Innervation
Obturator N
Functions of the Gracilis
- Flex Knee
- IR Tibia
- ADD Hip
- Flex Hip
What is the sequence of tendon insertions into the Pes Anserinus (sup -> inf)
Sup: Sartorius
Mid: Gracilis
Inf: Semitendinosus
Gastroc med head Prox Origin
Med Epicondyle of Femur
Gastroc Lat Head prox origin
Lat Epicondyle of Femur
Gastroc (both heads) dist Ins
calcaneal tubrosity via Achilles Tendon
Plantaris prox origin
Lat Epicondyle of Femur
Plantaris dist Ins
Calcaneal Tuberosity via Achilles Tendon
What Innervates the gastroc and Plantaris
Tibial N
Functions of the Gastrocnemius and Plantaris
- Flex knee
- Plaantar-flex Ankle
- Invert intertarsal
