The Knee [2] Flashcards
What are the major bones and joints of the knee?
Bones:
* femur
* tibia
* fibula
* patella
Joints
* tibiofemoral
* tibiofibular
* patellofemoral
Describe the MCL and LCL; what do they protect against and any major attachments?
MCL: protects from valgus forces and attctcahes to medial meniscus and joint capsule (protects knee from going inwards)
LCL: protects aginst varus force and is not attached to lateral meniscus (protects knee from going away from the midline)
Bonus: the unhappy traid is a tear of the medial meniscus, MCL, and ACL
Describe the ACL and PCL
ACL:
* acts as a restraint against anterior translation and internal rotation of the tibia (provides 86% of restraint)
* 2 bundles: anteromedial and posterolateral
PCL:
* restraint against posterior translation of tibia
* strongest and thickest ligament in the knee
* no rotational component here
* stronger than ACL
What is the Posterior Lateral Corner and what does it do?
(PCL)
It aids in rotational stability of the knee and includes 3 main structures
1. LCL (lateral collateral ligament)
2. PFL (popliteal fibular ligament)
3. PTU (popliteus tendon unit)
Describe the 2 menisci
- medial: c shaped
- lateral: O shaped
both provide cushion and stability due to the deepening of the socket
What does the transverese meniscal ligament do?
limits translation and stabilizes the menisci.
* it connects the medial and lateral menisci
Describe the meniscofemoral ligaments
It limits the translation of the lateral meniscus
* Anterior (humfrey’s): bifurcates and crosses over and behind the PCL
* Posterior (wrisberg’s): crosses over the PCL
What do the coronary ligaments do?
They limit the translation of menisci
and surround the tibial plateaus like a “crown”
- described as sutures
What are the 4 muscles of the quadraceps?
- rectus femoris (bi-articular); origin is AIIS
- vastus medialis;
- vastus lateralis
- vastus intermedius
- The vastus’s all originate on the femur
- All 4 inset into the tibial tuberosity on the patellar tendon
- Action: all extend the knee + the rectus femorus also flexes the hip
What are the OIA’s for the semimembranosus, semitendinosus, and biceps femoris?
Semimembranosus:
* O: ischial tuberosity
* I: medial condyle of tibia
Semitendinosus
* O: ischial tuberosity
* pes anserine
Biceps femoris
* O: long head originates at ischial tuberosity
* O: short head originates at linea aspera
* I: fibular head
All of them have the action of flexing the knee EXCEPT the biceps femoris short head will extend the hip
What are the OIA’s for the tensor fascia latte, sartorius, gracilious, and gastrocnemius
Tensor Fascia Latte:
* O: illiac crest
* I: gurdy’s tubercle
* A: abduct hip and extend & flex knee
Sartorius:
* O: ASIS
* I: pesansrine
* A: flexes the knee
Gracilis:
* O: ischial ramus
* I: pesanserine
* A: knee flexion
Gastrocnemius:
* O: medial and lateral head of the medial and lateral femoral epicondyle
* I: calcaneus
* Knee flexion + plantar flexion
What is the purpose of the popliteus?
- unlocks screw home mechanism
- also action is to flex the tibia and internally rotate tibia
What are the movements of the knee? and the degrees
Flexion:
- normal = 135-140
Extension:
- normal = 0
- up to 10 hyperextended
Tibial rotation: when we invert/evert the ankle the tibia follows suit
- internal and external rotation
Paterllar movements
Explain the screw-home mechanism?
Where the knee is in full extension and the tibia rotates to lock us into place
* when we are standing upright; the quads dont have to work hard bc of this mechanism that holds us aligned and in place
* the popliteus is what unlocks this
What are the 3 motions of the patella?
- glide: L&R, Up&down
- tilt: L&R, Up&down
- rotate/spin: L&R
Lot of freedom for motion here
