osteology: femur, tibia (Femoral condyles on tibial plateaus
joint type: hinge joint (hinge joints typically have 1 degree of freedom, internal/external rotation is the 2nd degree)
degrees of freedom: 2
flexion ROM: 1400
extension ROM: 100 of hyperextension possible
IR ROM: 300
ER ROM: 450 (internal/external rotation occurs when knee flexed @ about 300)
compared to other joints, what is different about the proximal end of the tibia?
what is the benefit of this:
the proximal end of the tibia is a flat, plateau others are concave/convex
benefit: does not allow for dislocations, less friction
describe the structure of the menisci:
what are the benefits of this design:
structural designcircular rims of fibrocartilage
thick at the peripheral borders
thin within the inner portions
(the thick/thin of each portion creates the concave shape)
benefits of designprovides for a more congruent joint
deepens tibial articular facets
shock absorption
describe the fxn of the medial and lateral menisci
supports the knee
cushions actions due to weight bearing
lateral menisciincomplete circle
less attachment; more movement or stretch
medial menisci"C" shaped
stronger attachment
injured more often
more often injured because it has a stronger attachments to the bone
attachment of the semitendinosis
the patellar ligament connects lower margin of patella with ____________:
the patellar ligament is a continuation of _________:
what is the fxn of the patellar ligament:
the patellar ligament connects lower margin of patella with: tuberosity of the tibia
the patellar ligament is a continuation of: the central fibers of the quadriceps tendon
fxn: provides patellar stability
what is the fxn of the oblique popliteal ligament:
protects against hyperextension
what are the 2 fxn of the medial (tibial) collateral ligament:
where does the MCL attach:
what type of force does the MCL resist:
which forces tears the MCL:
fxnsecures the medial condyle of the tibia to the medial epicondyle of the femur
checks extension
prevents lateral motion
where does the MCL attach: medial menisci
what type of forces does the MCL resist: valgus forces (abduction of the tibia)
torn: with laterally directed forcesmore frequently injured than the LCL
what are the 2 fxn of the lateral (tibial) collateral ligament:
what type of forces does the LCL resist:
which forces tears the LCL:
fxnssecures the lateral side of the head of the fibula to the lateral epicondyle of the femur
what types of forces does the LCL resist: varus forces (adduction of the tibia)
torn: with medially directed forces
LCL infrequently injured
what are the common characteristics of the ACL and PCL:
both are strong cordlike ligaments
cross (cruicate) within the knee
named due to the attachment to the tibia
limited extension & prevent rotation in exteneded position of the knee
describe the characteristics of the ACL:
passes up and back from the anterior tibia to the posterior femur
provides anterior stability
checks posterior slide of femur on tibia
most injures (from noncontact rotatary forces, and planting or cutting)
describe the characteristics of the PCL:
passes up and forward from the posterior tibia to the anterior femur
provides posterior stability
shorter and stronger than the ACL
checks anterior slide of the femur on tibia
not often injured (unless hyperextended)
describe the screw home mechanism:
WB, closed chain extension (seated to standing up)
as knee is extending; at about 300 flexed
the lateral femoral condyle (shorter) stops roll glide
medial femoral condyle continues posterior roll glide
causes interal rotation of the femur on the tibia
brings the knee into its more stable position:closed packed position
Which portion of the quadriceps is the largest muscle of the quadriceps group?
C. vastus lateralis
Which of the following is not considered a hamstring muscle?
A. rectus femoris
What muscle action is involved in the movement of the knee joints in the power phase of the standing long jump?
a.Concentric action of the hamstrings
b. Concentric action of the quadriceps
c. Eccentric action of the hamstrings
d. Eccentric action of the quadriceps
b. concentric action of the quadriceps
In performing a deep squat, which of the following is not an active muscle at the knee
a. Rectus femoris
b. Biceps femoris
c. Vastus lateralis
d. Vastus medialis
b. biceps femoris
External rotation of the knee is produced by which of the following muscles?
A. biceps femoris
Which muscle helps prevent lateral subluxation of the patella?
D. vastus medialis
Which of the following terms is used to describe someone who is bowlegged?
a. Genu varum
b. Genu valgum
a. genu varum
Bowlegged stance stretches which of the following ligaments?
a. Medial collateral ligament
b. Lateral collateral ligament
c. Anterior cruciate ligament
d. Posterior cruciate ligament
b. lateral collateral ligament
In landing from a vertical jump, what motion is occurring at the knees?
a. Flexion
b. Extension
c. Internal rotation
d. External rotation
a. flexion
What muscle action is involved in the movement of the knee joints in landing from a vertical jump?
a. Concentric action of the hamstrings
b. Concentric action of the quadriceps
c. Eccentric action of the hamstrings
d. Eccentric action of the quadriceps
d. eccentric actions of the quadriceps
how does the concentric action of the extensor muscles contribute to motion:
how does the eccentric action of the extensor muscles contribute to motion:
concentric actionimportant for ...
jumping
walking
running
eccentric actionwork body into slow landing
changing direction
list the anterior (quadriceps group) of extensor muscles:
rectus femoris
vastus intermedius
vastus lateralis
vastus medialis
what is the fxn of the rectus femoris:
how can this muscle become inactive:
fxn: strong, powerful extension
how can this muscle become inactive: when the hip is flexed
what is the fxn of the vastus intermedisu, vastus lateralis, vastus medialis:
which is the largest of this group:
which is the most active of this group:
fxn: extension
largest of the group: vastus lateralis; can cause lateral patellar subluxation
most active of the group: vastus medialis; prevents lateral disolcation of the patella
list the muscles of the posterior (hamstring group) of flexors:
biceps femoris
semimembranosus
semitendinosus
secondary flexorssartorius
gracilis
popliteus
gastrocnemius
the flexors of the knee are also secondary hip extensors
the ability to produce effective force at the knee is influenced by the position of other joints
what is the fxn of the biceps femoris:
flexion
external rotation in NWB
helps to stabilize posterolateral aspect of the joint
what is the fxn of the semimembranosus and semitendinosus collectively:
what is the fxn of the semimembranosus independently:
fxn: flexion, internal rotation in WB
semimembranosusdynamic medial stability
fibers attach to medial meniscus
with popliteus cause posterior motion of menisci during flexion
what is the fxn of the sartorius:
flexion
internal roation
activity more common with the hip
relativley impervious to active insuffiency
what is the fxn of the gacilis:
flexion (weak)
slight internal rotation
more primarily a hip flexor and adductor
actively insufficient if hip and knee flex together
what is the fx of the popliteus:
flexion
assists with internal rotation
unlocks the knee - to innitiate flexion, creates external rotation of the femur
with semimembranosus, pulls menisci posteriorly during flexion
what is the fxn of the gastrocnemius:
dynamic stabilizer
slight force to flexion
effective in preventing hyperextension
becomes actively insufficient easily
list the internal rotator muscles of the knee:
under what conditions can this motion happen:
semitendinosus
semimembranosus
popliteus
gracilis
sartorius
knee flexed at least 300
list the external rotators of the knee:
biceps femoris
possibly tensor fascia lata
how would you strengthen the quadriceps muscles:
resisted knee extension from a seated position
fxnal WB activites such as step-ups or squats
how would you strengthen the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedialis (the quadriceps group)?
knee extension activites against resistance
leg extensions
dead lifts
sumo dead lifts
dumbell squats
squats
front squats
angled leg press
power squats
hack squats
lunges
how would you stretch the rectus femoris, vastus lateralis, vastus medials, vastus intermedialis (the quadriceps group):
stretching
pulling the knee into maximum flexion
standing on one leg and pulling the heel of the other leg up to the buttocks
how can you strengthen the biceps femoris, the semimembranosus, and the semitendinosus (the hamstring group) muscles:
preforming knee or hamstring curls on a knee table against resistance
exercisesstanding leg curls
seated leg curls
lying leg curls
how can you stretch the biceps femoris, the semimembranosus, and the semitendinosus ( the hamstring group) muscles:
slow, static stretching
flexing the hip slowly while maintaining knee extension in a long sitting position
how do you strengthen the popliteus muscle:
how do you stretch the popliteus muscle:
strengthenhanging from a bar with legs flexed at the knee
walking, running
combine knee internal rotation and flexion exercises against resistance
sstretchpassive full knee extension without flexing the hip
passive max external rotation with the knee flexed to 20-30 degrees
