Knee FINAL Flashcards
2 articulations of the knee
tibiofemoral
patellofemoral
the medial & lateral condyles of the femur articulate with the ________, which are attached to the superior articular surface of the ______
- menisci
- tibia
the tibiofemoral joint is considered a ________ joint due to its restricting _______ & the occurrence of ________ motions
- modified
- ligaments
- rotation
what is the screw home mechanism
during the last few degrees of the knee extension, the anatomy of the knee requires the tibia to slightly externally rotate
explain the screw home mechanism
during the last few degrees of the knee extension, the anatomy of the knee requires the tibia to slightly externally rotate
when flexing the knee from a fully extended position, slight ____ of the _____ occurs
IR [internal rotation], tibia
what are menisci? what shape are they?
fibrocartilaginous discs located between the tibia and femur; semilunar shape
what do the menisci do?
distribute load at the knee to absorb shock
outer ___-___ % menisci receive blood supply
10-30%
what is the largest sesamoid bone
patella
the patella is formed within a _____
tendon
the patella rides in the ____ ______ of the femur, encased in the _______ tendon
- trochlear groove
- patellar
what is the posterior surface of the patella covered with? What does this do?
articular cartilage; reduces friction between patella and femur
the _______ surface of the patella contains ___ facets
posterior; 7
the patellofemoral joint has a ______ facet and a ______ facet
lateral; medial
what are the portions of the lateral and medial facets
- superior
- middle
- inferior
what is the odd facet of the patellofemoral joint
located on the far medial aspect; only comes into contact with the femur in full knee flexion
what does the patella do?
increases angle of pull of the quads on the tibia
the patella improves the mechanical advantage of the quadriceps as much as ___%
50%
what are the quadriceps muscles
- vastus medialis
- vastus lateralis
- vastus intermedius
- rectus femoris
what is the articulates genu
elevates the articular capsule of the knee joint
hamstring muscles
- biceps femoris short head
- biceps femoris long head
- semimembranosus
- semitendinosus
where is the popliteus located
deep in the popliteus fossa [posterior knee]
what muscle is known as the “key to the knee” muscle? why?
- Popliteus muscle
2. laterally rotates the tibia & unlocks the knee to begin knee flexion
the tibia can rotate when the knee is _______
flexed
what muscles contribute to tibial internal rotation
- semimembranosus
2. semitendinosus
muscle responsible for tibia external rotation
biceps femoris
ligaments of the knee are split into what two groups
cruciate ligaments and colateral ligaments
2 cruciate ligaments
- anterior cruciate ligament (ACL)
2. posterior cruciate ligament (PCL)
2 colateral ligaments
- medial colateral ligament [MCL]
2. lateral colateral ligament [LCL]
what is normal knee range of motion from flexion to extension? Up to ____ degrees of hyperextension is common
0-140 degrees; 15 degrees
normal level ground walking requires ___ to ____ degrees of knee flexion
60-120
normal level ground walking requires ___ to ____ degrees of knee flexion
60-120
after surgery it is very important to achieve full ROM, especially _____ in order to walk with a normal gait again
extension
running requires _____ to ____ degrees of knee flexion
120-140
to rise from a seated position at least ____ degrees of knee _____ is needed for most chairs; lower chairs may require _____ degrees
90; flexion; 115
what occurs in your knees biomechanically during a squat
surface motions between the tibia and femur: roll, slide & spin
what happens in your knees biomechanically during the first 10 degrees of a squat
spin occurs from the unblocking mechanism; slight posterior roll of femur on the tibia
What 3 things happen as you descend deeper in the squat
- condyles roll posteriorly on to the posterior aspect of the menisci
- the femur slides anterior proportionally with the deepness of the squat
- femoral translation is regulated by the ACL & PCL
the lowest compressive forces are at ____ degrees of knee flexion and at ___ degrees of knee flexion [in open chain]
90 degrees; 0 degrees
the highest compressive forces are at ___ degrees of knee flexion. What is significant about this angle?
25
- where pain is felt usually
- highest compressive forces
what two things are recommended for someone with patellofemoral pain
- perform leg extension ONLY from 90 deg. to 60 deg. of knee flexion
- perform “terminal knee extensions” [extend leg from 10-15 deg. flexion]
