11/30 Knee + Leg Flashcards
What is the superior border of the popliteal fossa?
Hamstrings
Laterally biceps femoris muscle
Medially semimembranosus muscle
What is the inferior border of the popliteal fossa?
Gastrocnemius muscle (lateral & medial heads)
What is the posterior (roof) border of the popliteal fossa?
Skin, popliteal fascia
What is the anterior (floor) border of the popliteal fossa?
Femur, investing popliteus fascia/muscle
What are the nerves of the popliteal fossa?
Sciatic nerve (L4-S3)
Branches into: Tibial nerve (L4-S3), common fibular nerve (L4-S2)
Where does the tibial nerve go? What is the cutaneous branching?
Continues within the posterior leg
Medial sural cutaneous nerve (contributes to sural nerve)
Where does the common fibular nerve go? What is the cutaneous branching?
Divides into superficial and deep fibular nerve
Continues within the lateral and anterior leg
Lateral sural cutaneous nerve (contributes to sural nerve)
What is the largest and most superficial joint?
The knee
What kind of joint is the knee?
Primarily a hinge type of synovial joint (flexion/extension), also does gliding and rotation about a vertical axis
What are the articulations of the knee?
2 femorotibial articulations, lateral and medial
1 femoropatellar articulation
What bone is not involved in the knee joint?
The fibula
The strength of the knee joint is dependent on?
Strength of the associated muscles and ligaments
What provides the most muscular stabilization of the knee? What is the most stable position of the knee?
Quadriceps femoris
Extended knee (taut ligaments)
What is the Q-Angle?
A line representing the resultant line of force of the quadriceps, made by connecting a point near the ASIS to the mid-point of the patella
A line of gravity, “weight-bearing line”.
What mechanism locks the knee in full extension?
“Screw Home” mechanism
Where does the “screw home” mechanism occur? What allows this to happen?
Occurs between 20 degrees of knee flexion and full extension
A combination of lateral rotation of the tibia and passive medial rotation of the femur
What is the result of the “screw home” mechanism
tightening of both cruciate ligaments, which locks the knee in extension
How does the “screw home” mechanism unlock?
Popliteus muscle initiates “unlocking” followed by lateral rotation of femur to enable knee flexion
What is the knee joint capsule made of?
External fibrous layer, internal synovial membrane
What is the external fibrous layer of the knee joint capsule?
Incomplete external portion of the capsule
What is the internal synovial membrane of the knee joint capsule?
Completely lines the articular cavity
Lines the internal surface of the fibrous layer laterally and medially but separates centrally
Posteriorly reflects into the intercondylar area almost separating the R&L femorotibial articular cavities
How is the joint capsule of the knee strengthened?
By 5 extracapsular ligaments
What are the 5 extracapsular ligaments which strengthen the knee joint (anterior/posterior)?
Anterior: Patellar tendon, fibular/lateral collateral ligament (F/LCL), tibial/medial collateral ligament (T/MCL)
Posterior: oblique popliteal ligament, arcuate popliteal ligament
What is the patellar tendon and where does it attach?
Distal extension of the quadriceps tendon
Attaches to tibial tuberosity
What is the Fibular/Lateral Collateral Ligament (F/LCL) and where does it attach?
Strong “cord-like” band of dense C.T.
Lateral epicondyle of femur to head of fibula
Where does the popliteus tendon pass?
Between Fibular/lateral collateral ligament and lateral meniscus
What is the Tibial/Medial Collateral Ligament (T/MCL)? Where does it attach?
Weaker than FCL
Medial epicondyle of femur to:
• Medial meniscus
• Medial surface of tibia
What is the Tibial/Medial Collateral Ligament (T/MCL) deep to?
Pes anserinus
What is the oblique popliteal Ligament?
Expansion of the semimembranosus tendon
Where does the arcuate popliteal ligament arise from?
Arises from the fibular head
Intra-articular ligaments originate and insert within the knee joint and consists of
Cruciate ligaments and menisci
Where do cruciate ligaments run?
cross obliquely within the joint capsule but outside the synovial cavity
What are the types of cruciate ligaments?
Anterior cruciate ligament (ACL)
Posterior cruciate ligament (PCL)
What does the anterior cruciate ligament (ACL) do?
Prevents anterior displacement of tibia on femur
Limits tibia movement anteriorly (knee flexed)
What does the posterior cruciate ligament (PCL) do?
Prevents posterior displacement of tibia on femur
Limits tibia movement posteriorly (knee flexed)
What are menisci?
crescent plates of fibrocartilage on the articular surface of the tibia
What do menisci do?
Deepen articular surface and absorbs mechanical load
What attaches to the menisci?
Coronary ligaments
Transverse ligament of the knee
MCL
Where are the coronary ligaments?
Extend from the joint capsule to the margins of the menisci/tibia
What does the transverse ligament of the knee do?
Joins the anterior margins of the menisci
What are the menisci of the knee?
Medial meniscus
Lateral meniscus
What is the medial meniscus?
C shaped
Attachment to TCL
What is the lateral meniscus?
Nearly circular
More mobile
What are the movements of the ankle?
Dorsiflexion (extension)
Plantarflexion (flexion)
What allows dorsiflexion of the ankle?
Muscles/tendons from the anterior compartment of leg
What allows plantarflexion of the ankle?
Muscles/tendons from the posterior and lateral compartments of leg
What movements does the foot allow?
Flexion/extension of toes
Stabilization of foot arches
What is the popliteal artery a continuation of? When does this change take place?
From femoral artery
After passing through adductor hiatus
Runs to inferior border of popliteus
What makes up the superior part of the knee anastomoses before the edge of patella? Where do they come from?
Descending branch of lateral femoral circumflex artery - from deep femoral (lateral)
Descending genicular artery - from femoral (medial)
What makes up the parts of the knee anastomoses surrounding the patella? Where do they come from?
Superior and inferior lateral genicular artery
Superior and inferior medial genicular artery
Middle genicular artery (posterior to anterior through knee joint)
All branch from popliteal artery (all but middle start posteriorly and come anteriorly around the sides of femur/tibia/fibula)
When the popliteal artery divides, what does it become?
Anterior and posterior tibial arteries
What does the anterior tibial artery give rise to?
Anterior tibial recurrent artery (part of genicular anastomosis)
What does the posterior tibial artery give rise to?
Fibular artery
What does the bowleg stance do to the coxa and genu angles? What about Q-angle and condylar separation?
Coxa valgus
Genu varus
Q-angle is decreased/smaller
Condylar separation laterally
What does the knock-knee stance do to the coxa and genu angles? What about Q-angle and condylar separation?
Coxa varus
Genu valgus
Q-angle is increased/bigger
Condylar separation medially
The anterior compartment of the thigh promotes this knee joint movement
Which nerve innervates these muscles?
Knee extension
Femoral nerve
The posterior compartment of the thigh promotes this knee joint movement
Which nerve innervates these muscles?
Knee flexion
Tibial nerve (short head of biceps femoris is common fibular)
Which muscles provide flexion of the knee? What is their innervation?
Gracilis - obturator nerve
Hamstrings (semitendinosus, semimembranosus, biceps femoris) - tibial nerve (short head of biceps femoris is common fibular)
Sartorius - femoral nerve
What makes up the pes anerinus?
semitendinosus, gracilis, and sartorius muscles
What is torn in a compound knee injury? What can also happen?
“Terrible triad”
Torn: anterior cruciate ligament, tibial collateral ligament, medial meniscus
Can also have a crushing injury to lateral meniscus
What muscles make up the anterior compartment of the leg? What movement do they perform?
Tibialis anterior, extensor hallicus longus, extensor digitorum longus, fibularis tertius
Dorsiflexion
What is the neurovascular supply to the anterior compartment of the leg?
Deep fibular nerve
Anterior tibial artery/vein
What muscles make up the lateral compartment of the leg? What movement do they perform?
Fibularis brevis, fibularis longus
Plantar flexion and eversion
What is the neurovascular supply of the lateral compartment of the leg?
Superficial fibular nerve
What muscles make up the posterior compartment of the leg? What movement do they perform?
Flexor digitorum longus, tibialis posterior, plantaris, soleus, gastrocnemius, flexor hallucis longus
Plantarflexion
What is the neurovascular supply of the posterior compartment of the leg?
Tibial nerve
Posterior tibial artery/nerve, fibular artery/nerve
