310 - Chapter 10: The Knee Joint

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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.


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