Functional Anatomy Week 3 - kinematics, knee joint and muscles Flashcards
2 types of linear motion
what do they mean
Rectilinear motion - all parts of an object or athlete move the same distance in the same direction at the same time
Curvilinear motion - same as rectilinear motion but over a curved path
Angular velocity
The rate of change of the angular position of a rotating body
General motion
A combination of linear and rotary motions
2 main forms of biomechanical analysis
Kinetics - study of relationships between the forces acting on the body and how those forces affect motion
Kinematics - geometry of the motion of objects which includes displacement, velocity and acceleration
Example of a spatial reference system
Cartesian coordinate system
-Joint is given a code, and tracked by cameras - used by FIFA on footballers
Scalars and vectors
Scalars have a magnitude - mass, distance, speed
Vectors have a magnitude and direction - velocity, weight, acceleration
How to calculate velocity
Change in displacement/change in time
If the velocity of an object is decreasing then its acceleration is
Negative
Conseravation of momentum
The total momentum of a system in any direction will remain constant unless an external force acts upon it
Momentum =
Mass x velocity
Impulse =
Force x time
Or the area under the force time graph
Impulse represents
A net external force and therefore produces a change in momentum
Impulse-momentum relationship using newtons 2nd law
Force = mass x acc
Acc = change in velocity/change in time
Times both sides by change in time
Force x time = mass x velocity
Using the formula force x time = mass x velocity, any change in impulse represents a
Change in velocity as mass is constant
Force, or external force, can also be represented as
Impact, as the external force is the impact of a body landing from a jump
2 joints in the knee
Patellofemoral joint
Tibiofemoral joint
Functions of knee joint
Support body weight (stability)
Transmit forces between femur and tibia (stability)
Provide movement (mobility)
Compromise between knee stability and mobility
Great stability in extension and great mobility in flexion
The tibiofemoral joint is a
Synovial, bicondylar joint between femoral condyles and tibial articular surfaces
Which femoral condyle’s articular profile is longer
Lateral
The ______ tibial condyle is larger and more oval shape
Medial
On top of the articular surfaces are
Semi lunar fibrocartilage discs called menisci
Function of menisci
Congruence between articular surfaces
Assist weight bearing across joints
Shock absorber
4 major ligaments
Anterior cruciate ligament (ACL)
Posterior cruciate ligament (PCL)
Medial collateral ligament (MCL)
Lateral collateral ligament (LCL)
2 extra capsular ligaments at the knee
The medial and lateral collateral ligaments
What does the medial collateral ligament prevent
Prevents valgus displacement –> abduction of a joint that isnt meant to abduct
Key information about the LCL
Attaches onto the fibula
Prevents varus displacement –> adduction of a joint that isn’t meant to adduct
2 intra capsular ligaments
ACL and PCL
Anterior cruciate ligament
Hands in pockets ligament
Prevents anterior tibial displacement (tibia moving forwards on the femur) - anterior cruciate ligament prevents anterior tibial displacement
Posterior cruciate ligament
Prevents posterior tibial displacement
Starts at the back
What is the patellofemoral joint
Synovial saddle joint betwen articular surface of patella and patella furface of femur
Type of bone the patella is
Functions of patella
Largest sesamoid bone in the body
Patella allows quadricep to pull the tibia around the femur and extension of the knee
Reduces friction
What happens to the patella during knee extension and flextion
During knee extension, patella moves proximally up the femur
During flexion, the patella moves distally
What is the joint capsule and what does it do
A fibrous bag of dense irregular connective tissue and holds synovial fluid in the joint
What are bursa
Fluid filled sacs designed to reduce friction
The tibiofemoral joint is a ____ joint
Biaxial joint
Movement occurs in 2 planes around 2 axis
Movements at the knee
Flexion and extension about horizontal axis in sagittal plane
Medial and lateral rotation about a vertical axis in the transverse plane
Closed pack position of the knee
The most stable position - extension - most contact between surfaces. No rotation possible in this position
When knee goes into closed pack position –> locking mechanism
Role of the popliteus in knee flexion
Unlocks the closed pack position
As it contracts it laterally rotates the femur on the tibia, allowing for knee flexion.
It attaches onto the meniscus and pulls the lateral meniscus backwards and stops it from getting trapped during knee flexion
Muscles that produce medial rotation of the tibia in flexion
Semiteninosus, semimembranosus, gracilis and sartorius
Muscles that produce lateral rotation of the tibia in extension
Long and short heads of bicep femoris
Muscles that produce knee flexion
Biceps femoris, semimembranosus, semitendinosus, sartorius, gracilis, gastrocnemius (medial and lateral head)
Muscles that produce knee extension
Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius, tensor fascia latae
Why does the gastrocnemius produce knee flexion
Both heads cross over the knee joint
Origin and insertion of the medial and lateral head of the gastrocnemius
Medial condyle of femur –> Achilles tendon
Lateral condyle of femur –> Achilles tendon
Origin and insertion of semitendonosus
Ischium –> tibia (anteriorly)
Origin and insertion of semimembranosus
Ischium –> tibia (more posteriorally)
Origin and insertion of gracilis
Pubis –>medial tibia at the pes anserinus
Origin and insertion of sartorius
ASIS –> medial side of tibia
Origin and insertion of long head of biceps femoris
Ishcial tuberosity –> head of fibula
Origin and insertion of short head of biceps femoris
Femur, attaches into same tendon as long head –> head of fibula
Muscles that cause knee extension
Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius, tensor fascia latae
Origin and insertion of rectus femoris
ASIS –> top of patella
Origin and insertion of vastus medialis and lateralis
medialis = upper part of femur, runs down linear aspera –> medial part of patella
lateralis = upper part of femur, runs down linear aspera –> lateral part of patella
Origin and insertion of vastus intermedialis
upper femoral shaft –> upper border of patella
What happens to the quadracep muscles when they connect into the patella
All 4 hamstring muscles connect into the upper border of the patella, then the ligament goes to the tibial tuberosity
