310 - Chapter 10: The Knee Joint
Knee flexion
- 140 degrees
Patellofemoral Joint
- arthrodial (gliding)
Poplitius
- assists in internal rotation
Knee External Rotation
- biceps femoris
what are the hamstrings?
- biceps femoris, - semimembranosus - semitendinosus
Quadriceps Group
- extends the knee - anterior compartment -rectus femoris, vastus lateralis, intermedius, and medialis
Muscle Force
- greater when lengthened than when shortened
Two-Joint muscles
- hamstring group - rectus femoris
Knee flexed 30 degrees or more
- internal rotation 30 degrees - external rotation 45 degrees
Hamstring Group
- knee flexion - posterior compartment - semitendinosus (medial) - semimembranosus (medial) - biceps femoris (lateral)
Bursae
- knee has more than 10 surrounding it - shock absorbers - prevent friction
Fibula
- lateral - does NOT articulate with femur or patella -attachment point for knee structures -NOT part of the knee joint
MCL (tibial)
- maintains medial stability - resists valgus forces, preventing abd of knee - commonly injured - contact sports, hit from the lateral side
Infrapatella Fat Pad
- posterior to patellar tendon - insertion point for synovial folds "plica"
Higher Q angles
- potential for knee problems and subluxations -important to maintain strength in vastus MEDIALIS
Knee Extension
- rectus femoris - vastus lateralis - vastus intermedius - vastus medialis
Hamstrings
- running muscles - very commonly strained
Knee Internal Rotation
- semitendinosus - semimembranosus - popliteus
"Unlocking the knee"
- tibia internally rotates from its externally rotated position
Full Extension of the knee
- tibia must externally rotate 10 degrees
Knee Joint
- tibiofemoral joint -largest joint in the body - hinge joint (ginglymus)
Most common injuries to the knee
-ACL injuries - noncontact, rotary forces, planting, cutting, hyperextension
Posterior Muscles
-Knee flexion - biceps femoris, - semimembranosus - semitendinosus - sartorius - gracillis - popliteus - gastrocnemius
What provides dynamic stability?
-Quads and hamstrings
Knee Flexion
-biceps femoris - semitendinosus - semimembranosus
Knee Hyperextension
-can be 10 degrees or more
Q Angle
-central line of pull for entire Quad group -runs from ASIS to the center of the patella -line of pull from patella tendon goes from center of patella -> tibial tuberosity - Angle formed is the intersection of the 2 lines - usually 15-20 degrees or less (more in females)
Menisci
-cushions -attached to the tibia - between bones - bigger "open" "C" is the medial menisci - smaller "closed C" is the lateral one -enhance stability -thicker on the OUTSIDE borders
Quads
-deceleration (eccentric) - jumping - 25-33% stronger than hamstring group (more heads)
Femoral Nerve
-innervates the knee extensors (quads)
Tibia
-medial - bears most of the weight
LCL (fibular) injuries
-not common
PCL injuries
-not common -direct contact
Ligaments
-provide STATIC stability
Anterior & Posterior Cruciate Ligaments
-provide anterior and posterior stability as well as rotary stability
Patella
-sesamoid (floating) bone - imbedded in QUADRACEPS & patellar tendon - serves to increase mechanical advantage like a pulley, IMPROVING the angle of pull
Sciatic Nerve
-tibial division -hamstring group
Knee Extension
-to 180 degrees
Synovial Cavity
-under the patella -capsule of the knee
How is the tibiofemoral joint formed?
a synovial hinge joint formed between three bones: the femur, tibia, and patella. Two rounded, convex processes (known as condyles) on the distal end of the femur meet two rounded, concave condyles at the proximal end of the tibia
hamstring primary movement
explosive running function in acceleration
vastus intermedius primary movements
extension of the knee
vastus lateralis primary movements
extension of the knee
vastus medialis - primary movement
extension of the knee
what are the primary movements?
flexion extension internal rotation external rotation
rectus femoris primary movement
flexion of the hip extension of the knee anterior pelvic rotation
popliteus primary movements
flexion of the knee internal rotation of the knee as it flexes
Anterior muscles
quadriceps **** Knee extension - rectus femoris - vastus medialis - vastus intermedius - vastus lateralis
what are the tibial menisci?
A meniscus is a piece of cartilage found where two bones meet (joint space). Menisci (plural of meniscus) protect and cushion the joint surface and bone ends. In the knee, the crescent-shaped menisci are positioned between the ends of the upper (femur) and lower (tibia) leg bones.
rectus femoris origin/insertion
O: anterior inferior iliac spine of the ilium and superior margin of the acetabulum I: superior aspect of the patella and patellar tendon to tibial tuberosity
vastus lateralis origin/insertion
O: intertrochanteric line, anterior and inferior borders of the greater trochanter, gluteal tuberosity, upper half of the linea aspera, and entire lateral intermuscular septum I: lateral border of the patella and patellar tendon to the tibial tuberosity
Poplitius
O: lateral aspect of lateral femoral condyle I: upper surface of posterior tibia
Fibular Collateral Ligament (LCL)
O: lateral femoral condyle I: fibular head
popliteus origin/insertion
O: posterior surface of the lateral condyle of the femur I: upper posterior medal surface of the tibia
vastus intermedius origin/insertion
O: upper 2/3 of the anterior surface of the femur I: upper border of the patella and patellar tendon to the tibial tuberosity
Tibial Collateral Ligament (MCL)
O: upper medial femoral condyle I: medial tibial surface
vastus medialis origin/insertion
O: whole length of the linea aspera and medial condyloid ridge I: medial half of the upper border of the patella and patellar tendon to the tibial tuberosity
what is the patellafemoral joint?
The knee is a hinge type synovial joint, which is composed of three functional compartments: the femoropatellar articulation, consisting of the patella, or "kneecap", and the patellar groove on the front of the femur through which it slides; and the
what is the tibiofemoral joint?
The knee joint joins the thigh with the leg and consists of two articulations: one between the femur and tibia, one between the femur and patella. It is the largest joint in the human body. The knee is a mobile trocho-ginglymus, which permits flexion and extension as well as slight internal and external rotation.