Chapter 10 The Knee Joint
Muscles: How many knee extensors are there?
- 4 quad muscles that extend
Muscles: How many knee flexors are there?
- 7 knee flexors *3 of them are hamstrings (biarticular- attach to both hip and knee)
Muscles: Vastus intermedius muscle
- Anterior knee joint muscle - extension of knee
Bones: Tibia?
- Bigger because bears the most weight
Joints: Anterior and posterior cruciate ligaments?
- Cross within knee between tibia and femur - vital maintaining anterior and posterior stability and rotatory stability
Bones: Fibular
- NOT part of knee joint - doesn't articulate w/ femur or patella -serves as attachment for knee joint structures
Muscles: Semimembranosus muscle
- Posterior knee joint muscle - Origin= Ischial tuberosity - Insertion= posteromedial surface of the medial tibial condyle - Action= Flexion of knee, extension of hip, internal rotation, posterior pelvic rotation
Muscles: Semitendinosus muscle
- Posterior knee joint muscle - Origin= ischial tuberosity -Insertion= upper anterior medial surface of tibia -Actions= Flexion of knee, extension of hip, internal rotation, posterior pelvic rotation *
How is dynamic stability produced?
- Quadriceps and hamstrings contractions
Whats the difference between a sprain and a strain?
- Sprain is elongation of ligament while strain is elongation of a muscle
What do ligaments provide?
- Stability
Knee Joint
-Largest joint in body - hinge joint
Joints: MCL Injuries
- Tibial (medial) collateral ligament - maintains medial stability by resisting valgus forces or preventing knee from being abducted - injuries occur commonly in contact or collision sports - teammate or opponent may fall against lateral aspect of knee or leg causing medial opening of knee joint stress to medial ligamentous structures
Muscles: Whats the Q angle?
- angle formed by the intersection of central line and line of pull at the patella - normally angle will be 15 degrees or less for males and 20 degrees or less in females - females have higher angles due to wider pelvis
Joints: ACL injuries
- anterior cruciate ligament most common serious injury to knee - involves non contact rotary forces associated with planting and cutting, hyperextension, or by violent quadriceps contraction which pulls tibia forward on femur
Muscles: Rectus femoris
- anterior knee joint muscle - extension of knee -flexion of hip - anterior pelvic rotation *
Muscles: vastus medialis muscle
- anterior knee joint muscle - extension of the knee
Joints: Patellofemoral joint
- arthrodial - gliding nature of patella on femoral condyle
What do menisci form?
- cushions between bones - attached to tibia - deepen tibial fossa - enhance stability
Bones: Where do femoral condyles articulate?
- enlarged tibial condyles
Muscles: Quadriceps muscle group
- extends knee - located in anterior compartment of thigh - consists of 4 muscles 1. rectus femoris 2. vastus lateralis 3. vastus intermedius 4. vastus medialus
Bones: What are medial and lateral tibial condyles ( medial and lateral tibial plateaus) receptacles for?
- femoral condyles
Joints: LCL Injuries
- fibular (lateral) collateral ligament infrequently injured
Muscles: what does popliteus assists in?
- medial hamstrings in knee internal rotation
Joints: PCL Injuries
- posterior cruciate ligament not often injured - mechanism of direct contact with an opponent or playing surface -
Muscles: Biceps Femoris muscle
- posterior knee joint muscle - Origin= ischial tuberosity, lower half of linera aspera lateral condyloid ridge - Insertion= lateral condyle of tibia head and head of fibula -Action= flexion of knee, extension of hip, external rotation, posterior pelvic rotation - short head attaches to knee long head attaches to both hip and knee
Muscles: what happens to individuals with higher Q angles?
- predispose people in varying degrees to a variety of potential knee problems including lateral patellar subluxation or dislocation, patellar compression syndrome, chrondromalacia, and ligamentous injuries - important to maintain high levels of strength and endurance in vastus medialis to counteract lateral pull of vastus lateralis
Muscles: Anterior knee joint muscles?
- primary knee extension - rectus femoris - vastus medialis - vastus intermedius - vastus lateralis
Muscles: Posterior knee joint muscles?
- primary knee flexion - biceps femoris - semimembranosus - semitendinosus * sartorius * gracilis * popliteus * gastrocnemius
Muscles that extend the knee?
- rectus femoris vastus lateralis vastus intermedius vastus medialis
Quads: Describe quad muscle group
- rectus femoris ( two-joint), vastus medialis, vastus lateralis(largest) - all attach to patella then to tibial tuberosity via patellar tendon - all are superficial and palpable except vastus intermedius(under rectus femurs)
Muscles: Hamstring muscles group
- responsible for knee flexion - located in posterior compartment of thigh - consists of 3 muscles 1. semitendinosus (medial internal rotator) 2. semimembranosus ( medial internal rotator) 3. biceps femoris (lateral external rotator)
Muscles: Whats the central line of pull for quads?
- runs from ASIS to the center of patella
Muscles: Whats the line of of pull for patella tendon?
- runs from center of patella to center of tibial tuberosity
Muscles: Hamstring muscle group
- semitendinosus (anteromedial tibia) - biceps femoris ( lateral tibial condyle and head of fibula) - semimembranosus (posteromedial tibia)
Bones: Patella?
- sesamoid(floating) bone - imbedded in quads and patellar tendon - serves as pulley in improving angles of pull resulting in greater mechanical advantage in knee extension
Muscles: Hamstring muscles
- strains very common - running muscles function in acceleration -antagonists to quadricep muscles at knee -ALL originate on ischial tuberosity of pelvis
Joints: Knee Joint proper
- tibiofemoral joint - ginglymus - also known as trochoginglymus -internal and external rotation occur during flexion
Muscles: What are biarticular muscles?
- two joint muscles - hamstrings and rectus femoris are biarticular
Quads: How can quad strength and power be indicated?
- vertical jump test - desired to be 25% to 33% stronger than hamstring group
Quads: Functions of quads?
- vital in jumping - functions as decelerator ( when decreasing speed to change direction) (when coming down from a jump) - eccentric contraction during decelerating actions - controls slowing of movements initiated in previous phases of the sports skill
Muscles: when are two joint muscles most effective?
- when either origin or insertion is stabilized to prevent movement in direction of the contracting muscle
Muscles: When are muscles able to exert the most force?
- when they are lengthened as opposed to shortened
Can menisci be torn?
-Yes, either or both may be torn in different areas from a variety of mechanisms, resulting in degrees of problems - tears often occur due to compression and shear forces during rotation while flexing or extending during quick directional changes in running
Muscles: Vastus lateralis muscle
-anterior knee joint muscle -all vastus muscles only extend - extends at the knee
Muscle: Popliteus muscle
- flexion of knee