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What are the main functions of the patella?
- increase mechanical advantage of quadriceps - protect the knee
What are the two joint muscles of the knee? (8)
- rectus femoris - long head of biceps femoris - semimembranosus - semitendinosus - sartorius - gracilis - gastrocnemius - tensor fasciae latae
What are the one joint muscles of the knee? (3)
- vastii - short head of biceps femoris - popliteus
What are the 2 types of end feel of the knee joint?
1. knee flexion = soft = soft tissue approximation (due to the contact between the muscle bellies of thigh and leg) 2. knee extension = firm = soft tissue stretch (due to the tension of joint capsule & ligaments)
What are the 3 arthrokinematic motions?
1. roll - rotary, one rolling on another 2. spin - rotary, one body spinning on another 3. slide - translatory, sliding on one joint surface over another
What is the normal range of Q angle?
13˚ - 19˚ tends to be greater in females due to wider hips
The cruciates are located within the joint capsule and are ∴ called?
Intracapsular Ligaments
A mobilizing force applied to the proximal tibia in a posterior direction will create what movement?
Knee Flexion
A mobilizing force applied to the proximal tibia in an anterior direction will create what movement?
Knee extension
What is genu recurvatum?
Knee hyperextension beyond 5˚
Tibial Tuberosity
Large projection at the proximal end on the anterior surface in the midline
The ACL attaches posteriorly on the?
Lateral condyle of the femur
The LCL provides stability to what side of the knee? Against what forces?
Lateral side of the knee against medial-to-lateral forces VarUS force
Fibers of the medial meniscus are attached to the?
Medial Collateral Ligament
The menisci are located?
On the superior surface of the tibia
What is special about the popliteus muscle?
One - Joint deep to the 2 head of the gastrocnemius originates on the lateral femur inserts on the medial tiba because it has an oblique line of pull, it creates the rotational pull needed to unlock the knee as it initiates knee flexion and tibial inward rotation
The 3 vasti muscles are what distinct type of muscle joint type?
One joint muscles
What is the Q angle?
Patellofemoral Angle
A mobilizing force applied to the proximal tibia, that creates knee flexion, moves the tibia in what direction in relation the femur?
Posterior Gliding Direction of tibia e.g. Posterior Drawer Test
Lateral Epicondyle
Projection proximal to the lateral condyle
Medial Epicondyle
Projection proximal to the medial condyle
Lateral Tibial Condyle
Proximal Lateral end
Medial Tibial Condyle
Proximal medial end
What is the Patellofemoral angle?
Q angle the angle between the quads (primarily rectus femoris) & the patellar tendon
The cruciates provide stability in what plane?
Sagittal
The last few degrees of motion lock the knee in extension. What is this called?
Screw-Home Mechanism of the knee
Superficially, on the hamstrings, is the _____________ on the medial side.
Semitendinosus
Deep to the superficial hamstrings is the _______________
Short head biceps femoris (laterally) (attaches to head of fibula) Semimembranosus (medially)
Adductor Tubercle
Small projection proximal to the medial epicondyle
What do the gracilis, sartorius, and tensor fasciae latae have in common?
Span the knee joint posteriorly Stabilize the knee joint Smaller in size in relation to other leg muscles do not have prime mover functions
The screw-home mechanism / full extension of the knee, allows an individual to do what?
Stand for a long time without using muscles
What are the borders of the popliteal space?
Superomedial border - semimembranosus & semitendinosus Superolateral border - biceps femoris. Inferomedial border - medial head of the gastrocnemius. Inferolateral border - lateral head of the gastrocnemius and plantaris.
What is a moment arm?
The perpendicular distance between the muscle's line of action and the center of the joint axis.
The lateral meniscus almost forms what shape?
circle
The knee has what relationship in open chain movements?
concave on convex concave tibial condyles glide posteriorly on femur with flexion, and anteriorly with extension
The knee has what relationship in closed chain movements?
convex on concave convex femoral condyles glide & roll posteriorly on the tibia with extension.
The medial meniscus from what shape?
crescent moon
Lateral Femoral Condyle
distal lateral end
Medial Femoral Condyle
distal medial end
How is the Q angle determined?
drawing a line from the ASIS to the midpoint of the patella drawing a line from the tibial tuberosity and the midpoint of the patella
The menisci are?
fibrocartilage discs
Where does the vastus lateralis, vastus medialis originate?
linea aspera
The popliteal space contains?
medial to lateral (AVN) Popliteal artery Popliteal vein Tibial nerve Common fibular nerve
When the knee is partly flexed the ACL keep the tibia from?
moving anteriorly
What is pes anserine?
muscle group made up of sartorius gracilis semitendinosus
Rectus Femoris OIAN
o: AIIS i: tibial tuberosity via patellar tendon a: hip flexion and knee extension n: femoral nerve L2, L3, L4 two joint muscle
Vastus Intermedius OIAN
o: anterior femur i: tibial tuberosity via patellar tendon a: knee extension n: femoral nerve L2, L3, L4 one joint muscle
Semitendinosus OIAN
o: ischial tuberosity i: anteromedial surface of proximal tibia aka pes anserinus a: hip extension, knee flexion, medially rotates tibia n: sciatic nerve L5, S1, S2, tibial part
Semimembranosus OIAN
o: ischial tuberosity i: posterior surface of medial condyle of tibia, (belly under semitendinosus) a: hip extension, knee flexion, medially rotates tibia n: sciatic nerve L5, S1, S2, tibial part
Vastus Lateralis OIAN
o: linea aspera i: tibial tuberosity via patellar tendon a: knee extension n: femoral nerve L2, L3, L4 one joint muscle
Vastus Medialis OIAN
o: linea aspera i: tibial tuberosity via patellar tendon a: knee extension n: femoral nerve L2, L3, L4 one joint muscle
Biceps Femoris OIAN
o: long head: ischial tuberosity o: short head: lateral lip of linea aspera, lateral supracondylar ridge i: fibular head (lateral condyle of tibia - muscle sheet) a: long head: hip extension, knee flexion a: short head: knee flexion, laterally rotates tibia
Popliteus OIAN
o: posterior surface, lateral condyle of femur i: proximal, posterior medial condyle/surface of tibia a: initiates knee flexion with inward tibial rotation, screw home mechanism n: tibial nerve L4, L5, S1
The smooth, posterior surface of the patella glides over the?
patellar surface of the femur
The articulation between the patella and femur is referred to as?
patellofemoral joint
The gastrocnemius and hamstring muscles provide...
posterior stability both medially and laterally
What are the 3 muscles collectively known as the hamstrings?
semimembranosus semitendinosus biceps femoris
The gracilis, sartorius provide...
spans the knee joint medially contribute to medial stability
Tensor Fasciae Latae...
spans the knee laterally essentially in the middle of the joint axis for flexion and extension contributes greatly to lateral stability
What is special about the gastrocnemius?
2 joint muscle crosses knee and ankle extremely strong plantar flexor but also has a significant role at the knee attaches by 2 heads at the medial and lateral condyles of the femur when it combines distally it forms the achilles tendon with the soleus and attaches to posterior surface of the calcaneus knee flexion & plantar flexion
What type of motion is the rotational component of the knee?
Accessory (it is not a free motion rather an accompaniment of flexion and extension)
A mobilizing force applied to the proximal tibia, that creates knee extension, moves the tibia in what direction in relation to the femur?
Anterior Gliding Direction of tibia e.g. Lachman test e.g. Anterior Drawer Test
Superficially, on the hamstrings, is the ___________ on the lateral side.
Biceps Femoris Long Head
Intercondylar Eminence
Double pointed prominence on the proximal surface at about the midpoint, which extends up into the intercondylar fossa of the femur
Because the collateral ligaments are placed superiorly and posteriorly they tighten during?
Extension
The ACL tightens during?
Extension
T/F The screw-home mechanism is an independent motion of the knee.
False This rotation is not an independent motion, is is not considered a motion of the knee.
LCL is aka?
Fibular collateral ligament
The collateral ligaments supply stability in what plane?
Frontal plane
The calcaneus is the final insertion point of the?
Gastrocnemius
Explain how the Gastrocnemius creates the standing movement for a person with paralyzed quadriceps.
Gastrocnemius contributes to knee extension, which may still happen without the quadriceps muscle function. In a closed kinetic chain action with the foot planted on the ground so that the distal segment is stationary, the proximal segment is moveable. There is also a reversal of this muscle action in which the femur is pulled posteriorly. This feature of the gastrocnemius muscle makes it possible for a person to stand upright without the use of the quadriceps muscles. The combined reverse muscle action of the gluteus maximus and gastrocnemius makes knee extension possible during stance. e.g. other moment of femoral posterior glide = anterior drawer test, and Lachman's test, which also creates knee extension.
The ACL prevents?
Hyperextension
How does the patella increase the mechanical advantage of the quadriceps?
The quadriceps moment arm is lengthened by placing the patella between the patellar tendon & the femur. - The action line of the quads is farther away. - Hence, the moment arm lengthens, allowing the muscle to have a greater angular force.
What is special about biceps femoris short head?
The short head of biceps femoris is the only part of the hamstring muscle group that has a function only at the knee. The other hamstring muscles have a function at both the hip and the knee.
The 3 vasti muscles and rectus femoris have one major thing in common, which is?
They all come together to the quadriceps aka patellar tendon, base, into the tibial tuberosity.
The lateral meniscus is thicker or thinner than the medial?
Thicker
What is significant about the screw-home mechanism?
This small amount of rotation of the femur on the tibia, or vice versa, keeps the knee from being a true hinge joint.
The cruciates are named for their attachment on the?
Tibia
MCL is aka?
Tibial collateral Ligament
The purpose of bursa is?
To reduce friction. Approx. 13 at the knee joint
T/F All 3 types of arthrokinematic motion occur during flexion & extension of the knee.
True
T/F During non-WB extension (open-chain) the tibia rotates laterally on the femur.
True
T/F Menisci absorb shock.
True
T/F Q angle must be measured while knee is in extension.
True
T/F The Q angle, bigger or smaller than normal range, is associated with Patellofemoral pain syndrome.
True
T/F The articular surface of the femoral condyles is much greater than that of the tibial condyles.
True
T/F The menisci deepen the the relatively flat joint surface of the tibia.
True
T/F It is the posterior gliding of the medial femoral condyle during the last few degrees of WB extension (closed-chain) that causes the femur to spin medially on the tibia.
True Spin Medially = Rotate Medially
T/F The articular surface of the medial femoral condyle is longer than that of the lateral femoral condyle.
True ∴ as extension occurs, the articular surface of the lateral femoral condyle is used up while some articular surface remains on the medial femoral condyle. ∴ the medial condyle of the femur must also glide posteriorly to use it entire articular surface.
T/F If the femur rolled on the tibia from flexion to extension, the femur would roll off the tibia before the motion was complete.
True ∴ femur must glide posteriorly on the tibia as it rolls into extension
In order for knee flexion to occur, the knee must be?
Unlocked by laterally rotating the femur on the tibia.
What type of joint is the knee?
Untrue Synovial Hinge Joint (untrue bc it has a rotational component)
The MCL provide medial stability and prevent excessive motion if there is what force?
Valgus force, lateral-to-medial force
When is the knee in the open packed position?
When it is flexed to 25˚ That is the position when most joint play is available.
The quadriceps provide...
anterior stability
Where does the vastus intermedius originate from?
anterior surface
The popliteal space is the area?
behind the knee
The PCL keeps the femur from...
being displaced anteriorly on the tibia
The ACL keeps the femur from ....
being displaced posteriorly on the tibia