Lecture 6: Tissues under load 4 Flashcards
what is a complex synovial joint?
when there is a simple joint plus extra structures
what is a compound synovial joint?
when there is more than two bones at a joint
what kind of joint is the knee?
a comound-complex synovial joint
in joints, which is more common, angular or linear movement?
angular. linear movement would be the lateral sliding of bones which is not good
what is the largest joint in the body?
the knee
what are the complex features in the knee joint?
- shape of the contributing bones (condyles, fossa and trochlea)
- intracapsular and extracapsular ligaments
- tendons
- menisci
which three bones form the knee joint?
tibia, femur and patella
why isn’t the fibula part of the knee joint?
because it doesn’t contribute to the articulation of the knee
why is the knee a compound joint?
because there are three articulating surfaces
what are the three articulating surfaces in the knee joint that makes is compound?
2 are found between the condyles of the tibia and femur
- lateral tibio-femoral joint
- medial tibio-femoral joint
- patellar-femoral joint
how is the patella a sesamoid bone?
because it isn’t attached to the femur by ligament, but instead sits in a trochlea
what is the function of the trochlea?
to prevent the patella from sliding laterally or medially
what is a meniscus?
like a rubber washer- a fibrocartilage ring that supports the femur
what is the intercondylar eminence?
acts as a plug, sits in the fossa and allows rotation of the knee joint
what is the intercondylar fossa?
the space between the condyles of the femur. it sits atop the intercondylar eminence and allows for movement of the femur and tibia anteriorly and posteriorly without moving them medially or laterally (linear movement prevented)
rotation of the knee can only occur when it is?
flexed
can your knee joint abduct and adduct?
lets bloody hope not
flexion and extension of the knee is movement in the ____________ plane, and it is pivoting around the ______________ axis
sagittal, medial-lateral or transverse
what are the adaptations made to the bone shape that allows for a larger angle of movement of the knee joint?
- curved ends of bones
- offsetting articulating surfaces (condyles ‘poke out’)
what is the negative side effect of offsetting the articulating surfaces at a joint?
one articular surface is longer than the other and the joint would roll off
what adaptation prevents the femur from rolling off of the tibia?
rolling and sliding anteriorly and posteriorly
- IF and IE is the adaptation that prevents medial and lateral sliding
rotation of the knee is movement in the ____________ plane, and it is pivoting around the ______________ axis
transverse, superior-inferior
what adaptation allows rotation of the knee joint?
the intercondylar eminence acting as a round pivot point for 360º rotation rather than just forwards and backwards movement
approximately how much rotation in degrees do we get while sitting?
70º
adduction and abduction of the knee would be movement in the ____________ plane, and would pivot around the ______________ axis
frontal, anterior-posterior
ligaments are made out of _________ connective tissue
dense connective tissue
the main purpose of ligaments is to?
distribute tensile loads to other structures within the joint, and limiting or controlling the limits of joint motion
what movement do ligaments prevent in the knee?
abduction and adduction
what are extracapsular ligaments?
ligaments that occur outside the articular capsule
what are capsular ligaments?
they form the outer fibrous layer of the articular capsule
what are intracapsular ligaments?
ligaments that are found inside the articular capsule
list the two collateral ligaments of the knee
- Tibial (or medial) collateral ligament (joins femur to tibia)
- fibular (or lateral) collateral ligament (joins femur to the fibula)
the collateral ligaments only work…?
when the knee is in full extension. during flexion these ligaments are loose.
what are the retinaculae?
fibrous connective tissue that stengthens the ligament and stabilises the patella in place, as the quads move the patella in multiple directions
which ligament does knee adduction break?
fibular (or lateral) collateral ligament
which ligament does knee abduction break?
tibial (or medial) collateral ligament
what feature of the knee prevents adduction and abduction in the unwanted plane?
the condyles
what are the intracapsular ligaments of the knee?
the cruciate ligaments:
- anterior cruciate ligament
- posterior cruciate ligament
where are the cruciate ligaments of the knee attached?
to the inside of the articular capsule - the intercondylar fossa
where are the attachments of the anterior cruciate ligament
attaches to the tibia anteriorly and the intercondylar fossa posteriorly
where are the attachments of the posterior cruciate ligament
attaches to the tibia anteriorly and the intercondylar fossa anteriorly
what movements does the anterior cruciate ligament resist in terms of the femur and tibia?
resists the posterior movement of the femur and the anterior movement of the tibia
what movements does the posterior cruciate ligament resist in terms of the femur and tibia?
resists the anterior movement of the femur and the posterior movement of the tibia
ligaments provide ________ stabilisation of the knee, whereas tendons and muscles provide _______ stabilisation of the knee
passive, active
how are the collateral ligaments both extracapsular and capsular?
because they transition from being outside the articular capsule to being a part of the articular capsule, but aren’t inside like the ACL and PCL.
what are the four muscles of the quadriceps femoris?
- rectus femoris
- vastus intermedius
- vastus medius
- vastus lateralis
which muscle attaches to the patella ligament
none, its a ligament between the patella and the tibia
where is the origin and insertion of the quadriceps?
origin is at the femur (unless it is rectus femoris, whose origin is at the ilium), insertion is at the patella.
where are the insertions of the hamstring muscles?
biceps femoris = lateral side of the tibia and the head of the fibula
semitendinosus = medial side of the tibia
semimbranosus = medial side of the tibia
what rotation does semitendinosus and semimembranosus contribute to if flexed alone?
medial or internal rotation
what rotation does biceps femoris contribute to if flexed alone?
lateral or external rotation
