Posterior Thigh & Knee Flashcards
What are the 2 bones of the leg?
How are they positioned relative to each other?
the tibia and the fibula
the tibia is much larger and lies medially
the fibula is much thinner and lies laterally
What part of the fibula is involved in the knee joint?
the fibula is NOT involved in the knee joint
only the proximal tibia articulates with the distal femur to form the knee joint
Label the components of the tibia, femur and fibula
What are the 3 articulations of the knee joint?
femorotibial articulations:
there is a medial and a lateral femorotibial articulation
femoropatellar articulation:
this is between the distal femur and the patella
What does the proximal aspect of the tibia provide important attachments for?
- ligaments that stabilise the knee joint
- muscles that move the knee joint
label the important bony landmarks on the anterior and posterior surfaces of the proximal tibia
What group of muscles insert onto the tibial tuberosity?
the quadriceps femoris tendon and the associated muscles:
- rectus femoris
- vastus lateralis
- vastus intermedius
- vastus medialis
insert onto the tibial tuberosity and extend the leg at the knee joint
How is the proximal fibula involved in the knee joint?
it is not part of the knee joint but it acts as an attachment site for ligaments that stabilise the knee and muscles that move theknee
What nerve is vulnerable to injury in fracture of the proximal femur?
the common peroneal nerve
this winds around the neck of the fibula
label the features of the proximal fibula
What are the 4 hamstring muscles found in the posterior thigh?
- semimembranosus
- semitendinosus
- long head of biceps femoris
- hamstring part of adductor magnus
What nerve innervates the muscles of the posterior thigh?
sciatic nerve
this bifurcates into 2 major nerves as it travels down the posterior thigh:
- tibial nerve
- common fibular (peroneal) nerve
complete the table describing the hamstring muscles
What are the functions of semimembranosus and semitendinosus?
- flex the leg at the knee joint
- extend the thigh at the hip joint
- medially rotates the thigh at the hip joint and leg at the knee joint
Why is the short head of the biceps femoris not considered a hamstring muscle?
it originates from the posterior aspect of the femoral shaft
it is not considered a hamstring muscle as it does not originate from the ischial tuberosity meaning that it CANNOT EXTEND THE HIP
label the hamstring muscles
What is the insertion, action and innervation of the short head of biceps femoris?
insertion:
head of fibula
action:
flexion of the leg at the knee joint
innervation:
common fibular division of sciatic nerve
What are the functions of both the adductor and hamstring parts of adductor magnus?
they can both adduct the hip
the adductor portion can also flex the hip
the hamstring portion can extend the hip
What is the action of the adductor magnus on the knee?
the adductor magnus cannot act on the knee
it attaches to the distal femur so does not span the knee joint
What is the insertion, action and innervation of adductor magnus?
insertion:
adductor tubercle and supracondylar line
action:
adduction and extension of the hip
innervation:
tibial division of sciatic nerve (L2, L3, L4)
Label the components of adductor magnus
What is the vascular supply of the posterior thigh?
branches from the inferior gluteal artery and perforating branches of the profunda femoris artery
the perforating branches perforate the adductor magnus through the adductor hiatus
How is the popliteal artery formed?
the femoral artery passes through the adductor canal, which ends in the adductor ihatus
after passing through the adductor hiatus, the femoral artery becomes the popliteal artery
What are the divisions of the popliteal artery?
at the lower border of popliteus, the popliteal artery bifurcates into:
- anterior tibial artery
- tibioperoneal trunk
The tibioperoneal trunk then divides into:
- posterior tibial artery
- fibular (peroneal) artery
label the arteries
What is the popliteal fossa?
a diamond-shaped depression located behind the knee
it is the main path by which vessels and nerves pass between the thigh and the leg
What are the borders of the popliteal fossa?
superomedial border:
semimembranosus
superolateral border:
biceps femoris
inferomedial border:
medial head of gastrocnemius
inferolateral border:
lateral head of gastrocnemius and plantaris
Label the borders of the popliteal fossa
What forms the floor and roof of the popliteal fossa?
Floor:
- posterior surface of the knee joint and the posterior surface of the femur
Roof:
- popliteal fascia and skin
- the popliteal fascia is continuous with the fascia lata of the leg
What are the contents of the popliteal fossa?
- popliteal artery
- popliteal vein
- tibial nerve
- common fibular nerve (common peroneal nerve)
What other vein enters the popliteal fossa?
the small saphenous vein pierces the popliteal fascia to enter the diamond and enter into the popliteal vein
How can disease of the popliteal artery affect the leg and foot?
it seriously compromises perfusion to the leg and food
this can lead to irreversible ischaemia and loss of the foot and/or leg
What are the 5 main ways in which the popliteal artery can become diseased?
- atherosclerosis
- popliteal artery aneurysm
- arterial embolus
- popliteal artery entrapment syndrome
- cystic adventitial disease
How may the popliteal artery become injured?
- knee dislocation
- complex tibial plateau fractures
- supracondylar femur fractures
How is the popliteal vein often diseased?
it is a deep vein that can become occluded by a blood clot in deep vein thrombosis
What type of joint is the knee joint?
How is it made stable?
it is a synovial hinge joint
the articular surfaces of the joint are incongruent, meaning that stability largely depends on surrounding soft tissue structures
(cartilage, ligaments and muscles)
label the components of the knee joint
What is the patella?
What is its structure like?
a triangular sesamoid bone that develops within the quadriceps tendon
it has a base, an apex and two surfaces (anterior and articular)
the articular surface has a medial and a lateral facet
What does the patella articulate with?
femoral condyles
the medial facet articulates with the medial condyle
the lateral facet articulates with the lateral condyle
what are these features of the patella?
What are the 2 main fucntions of the patella?
- leg extension
- protection
How is the patella involved in leg extension?
it enhances the leverage that the quadriceps tendon can exert on the femur
this increases the efficiency of the muscle
How is the patella involved in protection?
it protects the anterior aspect of the knee joint from physical trauma
What is meant by bipartite patella?
a condition in which the patella is composed of 2 separate bones
these bones usually fuse together in early childhood
Why is the patella at risk of lateral displacement?
the patella would be at risk of being excessively pulled and displaced laterally by the powerful lateral pull of:
- rectus femoris
- vastus intermedius
- vastus lateralis
when they contract
What are the 2 mechanisms that counteract the tendency of the patella towards lateral displacement?
- vastus medialis contracts to pull the patella medially at a horizontal/oblique angle
this counteracts lateral movement of the patella
- lateral femoral condyle projects more anteriorly than the medial femoral condyle to limit lateral movement of the patella
What happens if the lateral condyle is underdeveloped?
recurrent dislocation of the patella may occur
Why are patella dislocations more common in females?
the knee is positioned under the hip to return the centre of gravity to the midline
as females have wider pelves relative to the length of their femurs, their femurs lie at a relatively more oblique angle
a strong quad contraction is more likely to displace the patella
How is the patella often fractured?
by a direct blow
the patella can shatter or split but the fragments are not avulsed as the quadriceps expansion remains intact
What causes cartilage within the knee joint to become worn and torn?
What happens?
it can be worn and torn by repetitive use, traumatic injury, obesity and increasing age
when the cartilage wears away, the bony articular surfaces are exposed to each other
this is osteoarthritis
What is septic arthritis?
this occurs when there is infection within a joint
a septic knee is red, inflamed, warm and painful
What is meant by the tibial plateau?
What is the main issue with this?
the articular surfaces of the tibial condyles are practically flat - this area is the tibial plateau
a flat surface is a poor fit for the rounded femoral condyles
What are the menisci and what is their main function?
they are specialised cartilage that covers part of the tibial plateaus
this shapes and deepens the tibial articular surface so it is a better fit for the femoral condyles
What are the intercondylar tubercles attachment sites for?
the anterior and posterior cruciate ligaments
they are NOT covered by menisci
label the menisci
What are the 2 pairs of ligaments within the knee joint?
- anterior and posterior cruciate ligaments
- medial (tibial) and lateral (fibular) collateral ligaments
label the ligaments of the knee joint
What type of ligaments are the cruciate ligaments?
How are they repaired when damaged?
they are intra-articular ligaments that connect the tibia to the femoral condyles
they are repaired by using a tendon from another site to reconstruct the damaged cruciate
What is the origin, insertion and primary function of the anterior cruciate ligament?
origin:
intercondylar fossa of femur
insertion:
anterior intercondylar region of tibia
primary function:
prevents anterior dislocation of the tibia onto the femur
What is the origin, insertion and primary function of the posterior cruciate ligament?
origin:
medial femoral condyle
insertion:
posterior intercondylar region of tibia
primary function:
prevents posterior dislocation of the tibia onto the femur
How may the cruciate ligaments be injured?
- partially or completely torn
- completely avulsed from the tibia
What type of ligaments are the collateral ligaments?
extra-articular ligaments
What is the origin, insertion and primary function of the medial (tibial) collateral ligament?
origin:
medial femoral condyle
insertion:
medial margin and medial surface of tibia
primary function:
resists outwards turning forces on the knee
What is the origin, insertion and primary function of the lateral (fibular) collateral ligament?
origin:
lateral femoral condyle
insertion:
head of fibula
primary function:
resists inwards turning forces on the knee
What usually causes tears of the collateral ligaments?
tearing or stretching of the ligaments caused by forces which push the knee sidewayds
What usually causes a medial collateral ligament tear?
What other structure is often also injured?
a direct blow to the outside of the knee
this pushes the knee inwards (towards the other knee)
the tibial collateral ligament is attached to the medial meniscus, meaning they are often injured together
What usually causes a lateral collateral ligament tear?
a blow to the inside of the knee that pushes the knee outwards
What is meant by locking of the knee?
What is the benefit of this mechanism?
as the knee reaches full extension, there is a small degree of medial rotation of the distal femur on the tibia
locking increases the stability of the knee
What is meant by unlocking of the knee?
When does it occur?
when the knee is flexed from full extension, the first thing that occurs is unlocking
this involves a small degree of lateral rotation of the femur on the tibia
this is achieved by contraction of popliteus
What vessels create an anastomotic network around the knee joint?
the genicular arteries that arise from the popliteal artery
