Lower Limb Joints Flashcards
Classify all the joints of the lower limb
All are synovial except inferior tibiofibular joint
Classify hip joint accord to type, articular surface and stability
Type-Synovial ball & socket
Acetabulum and head of femur
Most stable joint because:
1. Shape of articular surfaces(deep acetabulum and small head, labrum increases concavity to prevent dislocation)
2. strong ligaments
3. Surrounding muscles
4. Atmospheric pressure
3 Accessory ligaments of the hip joint and their function
1.Iliofmeroal- preventing hyperextension
2. Pubofemoral- prevents hyper abduction
3. Ischiofemoral- prevents excessive medial rotation
Classify knee joint( include type, articular surfaces etc)
Synovial condylar, biaxial
Femoral and tibial condyles and patella
modified hinge( allows some med and lat rotation)
Describe the stabilty of the knee joint
relatively weak due to incongruency of articular surfaces
static= bones and ligaments, dynamic= muscles and tendons
**Ligaments:
1.capsular- fibrous capsule and is lined by synovial membrane{forms suprapatellar bursa)
2.ligamentum patellae- connects a
Functions of the knee menisci
1.Adapt femoral condyles to tibial condyles
2. Absorb shocks
3. Lubricate the articular surfaces
-Medial meniscus is more liable to injury because it is fixed( it is attached to the capsule and to medial collateral ligament)
Ligaments of the knee joint and function
- Medial(tibial) collateral - extends from medial epicondyle of femur to medial condyle of tibia
- Lateral(fibular) collateral - from lateral epicondyle of femur to styloid process of fibula
They prevent side to side displacement of the tibia
- Capsular ligament- deficient anteriorly
- Ligamentum patellae- tendon of insertion of quadriceps femoris
Inside:
1. Anterior cruciate ligament (ACL)- prevents hyperextension and displacement of tibia anteriorly
2. Posterior cruciate ligament (PCL)- prevents hyperflexion and posterior displacement of tibia
Factors maintaining knee joint stability
static= bones and ligaments, dynamic= muscles and tendons
Muscular factors:
-Strength and action of the surrounding muscles
-medial and lateral vastal retinacula
-ITB stabilizes slightly flexed knee
Ligamentous factors:
-Oblique polpiteal and collateral ligaments maintain side to side stability and stability in flexion
-Cruciate ligaments maintain anteroposterior stability
Bony factors:
-Intercondylar eminence of the tibia projects into intercondylar notch of femur preventing side to side displacement.
What are the relations of the knee joint?
Anteriorly:
-prepatellar bursa, patellar ligament, patella, patellar nerve plexus.
Anteromedially:
-Medial patellar(vastal) retinaculum
Anterolaterally:
-lateral patellar retinaculum and ITB
Posteriorly:
-Popliteal vessels, tibial nerve and oblique popliteal ligament
Posterolaterally:
-Tendon of biceps femoris, common peroneal nerve, lateral head of gastrocnemius and plantaris.
Posteromedially:
-Sartorius, gracilis,semitendinosus( pes anserinus), semimembranosus, medial head of gastrocnemius and popliteus
Describe the bursae around the knee joint.
Anterior bursae:
(a) subcutaneous prepatellar bursa(housemaid’s bursa)- in front of patella
(b) subcutaenous infrapatellar bursa- between skin and tibial tuberosity
(c) Deep infrapatellar bursa- between ligamentum patellae and upper part of tibia
(d) Suprapatellar bursa- upward extension of synovial membrane. Lies between lower part of femur and lower part of quadriceps femoris.
2. Lateral bursae:
(a) Bursa between fibular collateral ligament and biceps tendon.
(b) Bursa between lateral condyle of tibia and popliteus tendon-communicates with joint cavity
(c)Bursa between popliteus tendon and fibular collateral ligament
3. Medial bursae:
(a) Bursa between tendon of semimembranosus and medial collateral ligament
(b) Anserine- separates tendons of S.G.S from each other and from tibial collateral ligament
(c) Bursa between tendon of semimbranosus and medial condyle of tibia- may communicate with knee joint.
4. Posterior bursae:
(a) bursa between lateral head of gastrocnemius and capsule of joint.
(b) bursa between medial head of gastrocnemius and capsule of joint- brodie’s bursa
Describe the movements that occur at the knee joint.
- Flexion(hamstrings) and extension(quadriceps femoris)- differs from normal hinge movements; transverse axis is not fixed and there is conjunct rotation of the knee. Occur above menisci.
- Medial and lateral rotation- usually occur with flexion and extension (conjunct rotations) but may occur independently if the knee is flexed (adjunct rotations). Occur below menisci
Describe locking and unlocking mechanism.
1.Locking:(screw home mechanism)
When the foot is on the ground, medial rotation of femur on tibia during terminal phase of extension.Brought about by quadriceps femoris. When the knee is locked it becomes rigid and all the ligaments are taut.
** 2.Unlocking:**
When the foot is on the ground, Lateral rotation of femur on tibia during initial phase of flexion. Brought about by popliteus.Tight ligaments are untwisted therefore movement can occur. Unlocked knee can further be flexed.
during locomotion, locking and unlocking occurs simultaneously.
locking of the knee is essential for bearing load durin erect posture.
Name the chief muscles producing movement at the knee joint.
Flexion- semimembranosus, semitendinosus, biceps femoris ; popliteus(initiates flexion), sartorius, gracilis, gasrocnemius, plantaris
Extension- Quadriceps femoris ; TFL
Medial rotation- semitendinosus, semimembranosus, popliteus ; sartorius, gracilis
Lateral rotation- biceps femoris ; glut. max, TFL
x
Unhappy triad
- Tibial collateral
2.medial meniscus - Anterior cruciate ligament
Describe the blood supply of the knee joint.
Arterial anastomosis around the knee:
1. 5 genicular branches of popliteal artery.
2. descending genicular branch of femoral artery
3. descending branch of lateral circumflex femoral artery
4. two recurrent branches of anterior tibial artery.
5. circumflex fibular branch of posterior tibial artery
