Musculoskeletal: Anatomy - Knee joint and popliteal fossa Flashcards
What makes up most of the contents of the popliteal fossa?
Fat
Four superficial boundaries of the popliteal fossa
Superolateral: medial border of biceps femoris
Superomedial: semimembranosus and semitendinosus
Inferior: lateral and medial heads of gastrocnemius
Roof: skin, popliteal fascia
Three deep boundaries of the popliteal fossa
Superior: medial and lateral condylar lines of femur
Inferior: soleal line of tibia
Floor: popliteal surface of femur, posterior aspect of knee joint capsule, popliteus and investing fascia
Six contents of the popliteal fossa
- Termination of small saphenous vein (pierces popliteal fascia)
- Popliteal arteries and veins (and their branches)
- Tibial nerve
- Common fibular nerve
- Posterior cutaneous nerve of thigh
- Popliteal lymph nodes and lymphatic vessels
What is the popliteal fascia continuous with superiorly and inferiorly?
Superiorly: fascia lata
Inferiorly: deep fascia of leg
Branches of tibial nerve and their functions
- Motor to:
- Soleus
- Plantaris
- Gastrocnemius
- Popliteus
- Posterior compartment of leg - Medial sural cutaneous
- Joins sural communicating branch of common fibular to form the sural nerve (which then supplies sensation to the lateral leg and ankle) - Medical calcaneal, and medial and lateral plantar nerves:
- Sensory to dorsum of foot and posterior leg
- Medial and lateral plantar nerves supply intrinsic foot muscles
Where does the sciatic nerve divide into the tibial and common fibular nerves?
At the apex of the popliteal fossa
Describe the course of the tibial and common fibular nerves in the popliteal fossa
Tibial: bisects popliteal fossa vertically, exits between heads of gastrocnemius
Common fibular: lateral to tibial nerve, follows medial border of biceps femoris then exits passing superficial to lateral head of gastrocnemius and head of fibula before winding around neck of fibula
Four branches of the common fibular nerve and their functions
- Sural communicating branch:
- Joins medial sural nerve from tibial nerve to form sural nerve (supplies lateral leg and ankle) - Lateral cutaneous nerve of calf:
- Supplies skin over upper peroneal and extensor compartments - Superior and inferior genicular nerves:
- Travels with vessels to supply the knee capsule and lateral collateral ligament - Recurrent genicular nerve:
- Perforates tibialis anterior to supply capsules of superior tibiofibular joint and knee joint
Describe the course of the popliteal artery
Continuation of the femoral artery after it passes through the adductor hiatus
Ends at inferior border of popliteus by dividing into anterior and posterior tibial arteries
List in order of most superficial to deepest in the popliteal fossa: veins, arteries, nerves
- Nerves
- Veins
- Arteries
Five genicular branches and four muscular branches of the popliteal artery
Five genicular:
1. Superior medial
2. Superior lateral
3. Middle
4. Inferior medial
5. Inferior lateral
Four muscular:
1. To hamstrings
2. To soleus
3. To plantaris
4. To gastrocnemius
Which arteries make up the genicular anastamosis?
- Branches of popliteal artery:
- Superior medial
- Superior lateral
- Middle
- Inferior medial
- Inferior lateral - Branch of femoral artery:
- Descending genicular - Descending branch of lateral femoral circumflex
- Branch of anterior tibial artery:
- Anterior tibial recurrent
Describe the course of the popliteal vein
Begins at distal border of popliteus as continuation of posterior tibial vein
Receives small saphenous vein in the popliteal fossa after it pierces the popliteal fascia
Becomes femoral vein as it passes through the adductor hiatus
Describe the relation of the popliteal vein to the popliteal artery and tibial nerve within the popliteal fossa
Inferiorly: lies posteromedial to popliteal artery and lateral to tibial nerve
Superiorly: overlies popliteal artery with tibial nerve on top
Where do the popliteal lymph nodes drain to?
Deep inguinal lymph nodes
Where do the superficial popliteal lymph nodes receive lymph from?
Lymphatics accompanying the small saphenous vein
Where do the deep popliteal lymph nodes receive lymph from?
From joint capsule of knee and from lymphatics accompanying the deep veins of the leg
Proximal and distal attachment, course of tendon, innervation and action of popliteus
Proximal: lateral femoral condyle and lateral meniscus
Distal: posterior tibia, superior to soleal line
Tendon course: lies within capsule of knee joint (enters beneath arcuate popliteal ligament)
Innervation: tibial nerve (L4-5, S1)
Action: weak knee flexor, unlocks knee during flexion (by rotating femur laterally on fixed tibia), acts with PCL to prevent anterior displacement of femur on tibia
What are the three articular surfaces of the knee?
- Medial tibiofibular
- Lateral tibiofibular
- Femoropatellar
Describe the posterior surface of the patella
Larger lateral and smaller medial surface
What gives the knee joint its stability?
Mechanically relatively weak due to incongruent surfaces
Dependent on strength and action of surrounding muscles and tendons, and connecting ligaments
What is the most important stabiliser of the knee?
Quadriceps tendon (particularly inferior fibres of vastus medialis and lateralis)
What is the most important stabiliser of the patella?
Inferior fibres of vastus medialis
Describe the capsular attachments of the knee
Superoposterior: proximal margins of femoral condyles and intercondylar fossa (with attachment to lateral condyle interrupted by aperture for popliteus tendon)
Inferoposterior: tibial plateau (again with aperture for popliteus tendon)
Anterior: replaced by quadriceps tendon, patella, and patellar ligament (with deficiency in attachment to femur above level of patella: allows communication between joint and suprapatellar bursa)
Medial: articular margins of femur and tibia with attachment to medial meniscus and medical collateral ligament
Lateral: proximal to groove for popliteus tendon, and surrounds head of fibula with attachment to lateral meniscus
Five extra-capsular ligaments of the knee
- Patellar ligament (distal quadriceps tendon)
- Lateral collateral ligament
- Medical collateral ligament
- Oblique popliteal ligament
- Arcuate popliteal ligament
Describe the structure of the patellar ligament
Distal part of quadriceps tendon
Also receives medial and lateral retinacula from vastus medialis and lateralis respectively
Describe the anatomy of the lateral collateral ligament. How does it relate to the biceps femoris and popliteus tendons?
Extends from lateral femoral epicondyle to lateral surface of fibular head
Splits biceps femoris tendon in two
Separated from lateral meniscus by popliteus tendon
Describe the anatomy of the medial collateral ligament. How does it relate to pes anserinus and the medial meniscus?
Extends from medial femoral epicondyle to medial tibial condyle and superomedial tibial surface
Crossed by pes anserinus (tendons of sartorius, gracilis and semitendinosus)
Attaches to medial meniscus at midpoint
What are the major differences between the lateral and medial collateral ligaments?
Lateral collateral is stronger and cord-like
Medial collateral is weaker and flat
Describe the anatomy of the oblique popliteal ligament
Expansion of semimembranosus
Crosses intercondylar fossa from posteromedial tibial condyle to superolateral femoral condyle to reinforce joint posteriorly
Blends with posterior capsule
Describe the anatomy of the arcuate popliteal ligament
Y-shaped ligament
Strengthens capsule posteriorly
Passes from posterior fibular head superomedially over popliteus tendon to posterior tibial intercondylar area
Lateral limb attaches to lateral femoral condyle
Seven intracapsular ligaments of the knee
- Anterior cruciate ligament
- Posterior cruciate ligament
- Medial meniscus
- Lateral meniscus
- Coronary ligaments
- Transverse ligament of knee
- Posterior meniscofemoral ligament
What are the major differences between the anterior and posterior cruciate ligaments?
Anterior: longer, weaker, poor blood supply
Posterior: shorter, stronger
Describe the anatomy of the anterior cruciate ligaments
Extends from anterior intercondylar tibia (posterior to medial meniscus) to posteromedial aspect of lateral femoral condyle
What is the role of the anterior cruciate ligament?
Prevents posterior displacement of femur on tibia in extension
Prevents hyperextension
How is the anterior cruciate ligament tested?
With anterior draw test with knee in 90 degrees of flexion
Describe the anatomy of the posterior cruciate ligament
Extends from posterior intercondylar tibia and passes medially to ACL to insert at anterolateral aspect of medial femoral condyle
What is the role of the posterior cruciate ligament?
Prevents anterior displacement of femur on tibia
Prevents hyperflexion
How is the posterior cruciate ligament tested?
With posterior draw test with knee in 90 degrees of flexion
What are the major differences between the medial and lateral menisci?
Medial: C shaped, broader posteriorly than anteriorly, less mobile (attached to MCL -> more prone to tears)
Lateral: nearly circular, smaller and more freely mobile than medial
Describe the attachments of the medial meniscus
Attached anteriorly to anterior intercondylar tibia (anterior to ACL)
Attached posteriorly to posterior intercondylar tibia (anterior to PCL)
Attaches to MCL medially
Describe the attachments of the lateral meniscus
Attached anteriorly to anterior intercondylar tibia (posterior to ACL)
Attached posteriorly to posterior intercondylar tibia (anterior to PCL)
What are the coronary ligaments?
Portions of the knee joint capsule between margins of menisci and periphery of tibial condyles
What structures are joined by the transverse ligament of the knee?
Joints anterior aspects of medial and lateral menisci to tether them together during knee movement
What structures are joined by the posterior meniscofemoral ligament?
Joins lateral meniscus to PCL and medial femoral condyle
How many bursae are in and around the knee joint?
At least 12
Describe the eight named bursae of the knee joint. Where are they located? Which communicate with the knee joint?
Anterior:
1. Subcutaneous prepatellar: between skin and anterior patella
2. Subcutaneous infrapatellar: between skin and tibial tuberosity
3. Deep infrapatellar: between patellar ligament and anterior tibia (separated from knee joint by fat pad)
4. Suprapatellar*: between femur and quadriceps tendon
Posterior:
1. Popliteus: between popliteus tendon and lateral tibial condyle
2. Anserine: between pes anserinus, and MCL and media tibia
3. Gastrocnemius*: deep to tendon of medial head of gastrocnemius
4. Semimembranosus: between medial head of gastrocnemius and semimembranosus tendon
Which artery pierces the knee joint capsule? What does it supply?
Middle genicular artery pierces joint capsule to supply the cruciate ligaments, synovial membrane, and peripheral menisci
Four nerves supplying the knee joint
- Femoral: branches to vasti supply anterior aspect
- Tibial: genicular branches supply posterior aspect
- Common fibular: genicular branches supply lateral aspect
- Saphenous: articular branches supply medial aspect
What are the primary and secondary muscles responsible for knee flexion?
Primary: hamstrings (biceps femoris, semimembranosus, semitendinosus)
Secondary: gracilis, sartorius, popliteus, gastrocnemius, plantaris
What are the primary and secondary muscles responsible for knee extension?
Primary: quadriceps femoris
Secondary: tensor fascia lata
What are the primary and secondary muscles responsible for medial rotation of the knee?
Primary: semitendinosus, semimembranosus
Secondary: popliteus when knee in extension
What are the primary and secondary muscles responsible for lateral rotation of the knee?
Primary: biceps femoris
