Clinical Abatomy Of The Lower Limb 2 Flashcards
Describe the knee joint
The knee joint is the largest synovial joint in the body
Type: hinge
-articulation between the femoral condyles and superior aspect of tibial condyles
-articulation between the patella and the femur
Describe the two menisci of the knee joint
Fibrocartilaginous C-shaped cartilages
- menisci increase the congruency between the tibial and femoral
- attached medially to the intercondylar region of the tibia
- medial meniscus: attached around its margin to the capsule of the joint and to the tibial collateral ligament
Lateral meniscus: unattached to the capsule as tendon of the popliteus muscle passes between them
What connects the two menisci of the knee?
Transverse ligament of the knee connects the anteriorly
What is the function of the patellar ligament?
Pateliar ligament: the continuation of the quadriceps femoris tendon inferior to the patella
Contrast the tibial(medial) collateral ligament and the fibula (lateral) collateral ligament
Tibial (medial) collateral ligament- medial femoral Condyle to the medial aspect of tibia (deep fibers are attached to the medial meniscus)
Fibulae (lateral) collateral ligament-lateral femoral condyle to the fibular head
What is the function of the anterior Cruciate ligament?
-attaches on the anterior part of the intercondylar area of the tibia and ascends posteriorly to attach at the back of the lateral wall of the intercondylar fossa of the femur
- prevents anterior displacement of the tibia relative to the femur
- prevents posterior displacement of the femur
What is the function of the posterior Cruciate ligament?
-attaches to the posterior aspect of the intercondylar area of the tibia and ascends anteriorly to attach to the medial wall of the intercondylar fossa of the femur
- Restricts posterior displacement of the tibia relative to the femur
- restricts anterior displacement of the femur
Explain the locking mechanism
When standing, the knee joint is locked into position, thereby reducing the amount of muscle work needed to maintain the standing position.
Locking mechanism is achieved by:
-The change in the shape and size of the femoral surfaces that articulate with the tibia dueling extension. The joint surfaces become larger and more stable in extension.
-medial rotation of the femur on the tibia during extension that tightens all the associated ligaments
The popliteus muscle unlocks the knee by initiating lateral rotation of the femur on the tibia
What causes genu varus & valgus ?
Changes in the distribution of weight to the tibia can cause increase or decrease in the space between the femur and patellar
Genu varus- knees bow outward, giving bow legged appearance
Genu valgus- inward bending at the knees
What is the unhappy triad?
Excessive force to the lateral side of the knee (valgas pressure):
- medial collateral (most common)
- anterior cruciate
- medial memiscus/lateral meniscus
Describe the knee bursae
Anteriorly, the synovial membrane is separated from the patellar ligament by an infrapatellar fat pad
Suprapatellar bursa: continuous with the Articular cavity superiorly between the distal end of the shaft of the femur and the quadriceps femoris muscle and tendon
Aside from knee bursae, what other bursae exist that associate with the knee, but not normally communicating with the artcular cavity ?
These include:
- subcutaneous prepatellar bursa (housemaid knee-pratellar bursitis)
- deep and infrapatellar bursa
- subcutaneous infrapatellar bursa (clergyman’s knee)
Summarize blood supply to the knee
5 genicular arteries from the popliteal artery
-superior medial genicular
- superior lateral genicular
- inferior medial genicular
- inferior lateral genicular
- middle genicular
Recurrent branch of anterior tibial artery
2 descending genicular arteries
- one from femoral artery
- one from the lateral circumflex
Explain the leg compartments/divisions
The leg is divided into anterior, posterior and lateral compartments by:
- interosseous membrane
- fascia cruris (deep fascia)
- two inter muscular septa (fibula to deep fascia)
- direct attachment of the deep fascia to the periosteum of the tibia
What are the compartments of the leg?
Lateral compartment-
-superficial fibular nerve= eversion of foot
- Anterior compartment= extensor compartment, deep fibular nerve
- dorsiflexion (extension) of foot
- inversion
- Posterior compartment= flexor compartment, tibial nerve
- planterflexion (flexion) of the foot
- inversion
What are the muscles of the posterior compartment of the lower limb?
- gastrocnemius
- soleus
- plantaris
- tibialis posterior
- flexor digitorum longus
- flexor hallucis longus
- popliteus
What are the posterior compartment of the motor and sensory innervation of the lower limb?
Tibial nerve
What is the opening(canal) of the posterior compartment of the lower limb
Medial tarsal tunnel
What is the blood supply of the posterior compartment of the lower limb?
Posterior tibial artery
What are the general functions of the posterior compartment of the lower limb?
Planter flexion of the ankle joint, tibialis posterior also inverts, flexion of digits
What is the innervation and function of the gastrocnemius?
Tibial nerve
-plantar flexes ankle joint/foot and flexes the knee/leg