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