Knee, popliteal fossa and leg Flashcards
What bones does the knee joint include?
articulation between the distal end of femur (medial and lateral condyles) and proximal tibia (tibial plateau) Also arguably includes the posterior aspect of the patella *note the fibula is NOT included*
find the following landmarks of the knee joint
- lateral/medial epicondyle
- latera/medial condyl of the femur
- patellar surface
- intercondylar fossa
- supracondylar line
Find the following landmarks of the tibia/fibula
- head of fibula
- neck of fibula
- fibullar lateral malleolus
- intercondylar eminence
- tibial tuberosity
- tibial medial malleolus
- soleal line
Why does it hurt so bad to be kicked in the shin?
Because your tibial crest is most anterior and there is no muscular coverage - also why it does not heal well.
What kind of joint is the knee?
modified hinge synovial joint
Describe a synovial joint
- 2 or more bony articulating surfaces
- articular capsule
- synovial membrane
- synovial fluid
- hyaline cartilage
Describe the menisci in the knee
semi- lunar fibrocartilage (medial and lateral)
they deepen the articular surface and act as a cushion
the upper surfaces are in contact with the femoral condyles and the lower surfaces are in contact with the tibial condyles
Name the major ligaments and tendons of the knee joint
- tendon of the quadriceps femoris
- patellar ligament
- tibial (medial) collateral ligament
- fibular (lateral) collateral ligament
- patellar retinacula
- oblique popliteal
What tendon does the patella sit in?
What do you call a bone that grows within a tendon?
The patella is a ‘sesamoid’ bone that sits within the quadriceps tendon in this case.
What are the attachements of the patellar ligament?
lower border of the patella to the tibial tuberosity
What are the attachments of the medial collateral ligament?
attaches from the medial femoral epicondyle to the medial tibia
*it is attached to the medial meniscus - clinically, damage to this ligament could potentially tear the meniscus- damage to the meniscus is difficult to repair due to lack of blood supply*
What are the attachments of the lateral (fibular) collateral ligament?
this ligament is thin and cord-like extending from the lateral femoral epicondyle to the head of the fibula. it is NOT attached to the lateral meniscus or capsule
the popliteus tendon passes inbetween the ligament and the lateral meniscus
Describe the intracapsular ligaments of the knee
Anterior cruciate ligament (ACL) - the ACL stops the tibia from moving forward or femur from sliding posteriorly - attachments from lateral femoral condyle to the anterior tibia
Posterior cruciate ligament (PCL) - stops the tibia from moving backwards or the femur from sliding anteriorly- originates in the medial femoral condyle and inserts at the back of the tibia - the PCL lies medially to the ACL
*called cruciate ligaments because they ‘cross’*
What are the movments at the knee?
flexion (hamstrings- tibial/sciatic nerve)
Extension (quads- femoral nerve)
Medial and Lateral rotation - occurs when knee is in flexion by contraction of alternate hamstring muscles
How and why does the knee ‘lock’ and ‘unlock’?
Why? increased stability while standing - less energy use
Locking: happens in full extension- femur rotates medially on tibia
unlocking: ligaments become untwisted and relaxed
*popliteus muscle LATERALLY rotates the femur on the tibia*
Name the synovial bursae
- Suprapatellar bursa - behind quads tendon
- prepatellar bursa- responsible for ‘housemaids knee’ anteior to patella
- infrapatellar bursa- deep to patellar ligament responsible for cleryman’s knee
- semimembranosus bursa- between membrane and joint
- popliteal bursa- communicates with joint cavity
What is the blood supply/nerve supply to the knee?
blood = genicular arteries and popliteal artery
nerve= (remember hilton’s law - the nerve supplying the muscle that crosses the joint also innervates it) - femoral nerve, tibial nerve, and common peroneal nerve
How to test for ACL rupture?
‘Anterior Drawer Test’ = ask to lay down with knees up and feet on table - pull leg towards the foot of the bed and if the tibia moves more than 5 mm anteriorly (not stopped by the ACL) then the acl is damaged
What are the attachments of the popliteus?
from the popliteal surface of the tibia to the lateral condyle of femur and lateral meniscus
Is the popliteus muscle intra capsular?
Yes, it is intracapsular but extrasynovial
What is the action of the popliteus muscle?
laterally rotates the femur on the tibia to ‘unlock’ knee
What is the innervation of the popliteus muscle?
tibial nerve
Follow the path of the femoral artery to it’s termination
The femoral artery travels down the subsartorial canal (hunter’s canal) - then passes through the adductor hiatus to become the popliteal artery. The popliteal artery runs posterior to the knee and sends branches to the gastrocnemius and forms the genicular arteries of the knee joint. The popliteal artery then divides into the anterior tibial (anterior compartment) and the posterior tibial (posterior compartment) and the peroneal artery (lateral compartment)
Where are the articulating surfaces of the tibia and fibula?
Tibia: articulates with the femoral condyles at the knee and the Talus at the ankle - also the fibula at the tibiofibular joint (immovable)
Fibula: articulates with the tibia via tibiofibular joint (immoveable) and the lateral side of the talus (talofibular joint)
What is the purpose of the fibula?
It does not play a role in the knee joint, but it is a site of muscle attachment and is great for weight bearing as well as stability
Describe the movements at the ankle joint
dorsiflexion= toes up towards the ceiling - Anterior compartment
Plantarflexion= plant foot down = posterior compartment
eversion of foot = Lateral compartment
inversion of foot = posterior compartment
Name the muscles of the anterior compartment of the leg
All supplied by the deep peroneal nerve (L5,S1)
- tibialis anterior
- extensor digitorum longus
- extensor hallucis longus
- fibularis brevis
Name the muscles in the posterior muscle compartment
Supplied by the tibial nerve (L5- S1,2,3)
- deep =
- tibialis posterior
- flexor digitorum longus
- flexor hallucis longus
- superficial =
- gastrocnemis
- soleus
- plantaris
Name the muscles of the Lateral compartment of the leg
supplied by the superior peroneal nerve (L5, S1)
- fibularis longus
- fibularis brevis
What is the medical term for a tendon that pulls out a fraction of bone?
Avulsion Fracture
Which structure in the popliteal fossa is nearest to the femur?
The popliteal artery - which is why a femoral fracture in this area is particularly dangerous
where does the popliteal artery start? Where does it end?
The popliteal artery begins after the femoral artery passes through the adductor hiatus -
It ends when it splits into the anterior and posterior tibial arteries
Which region of the lower limb is drained by the popliteal lymph nodes?
They receive lymph from the lateral superficial vessels. (so the lateral leg)
Which nerves send branches to the knee joint?
femoral, tibial and common fibular nerves
define on the skeleton the capsular attachments of the knee joint - which regions of the joint are not covered with synovial membrane?
the intercondylar space is not covered by synovial membrane or capsule - this region is an attachment site for the ACL and PCL
What mechanism keeps the knee joint fixed while standing?
The popliteus muscle pulls the tibia medially ‘unlocking’ the fixed knee joint- but while standing the tibia moves laterally to fit against the femur without any muscle use whatsoever- this allows you to stand without exertion for long periods of time
What structures are attached to the medial meniscus and the lateral meniscus of the knee?
Lateral meniscus - attached to the ACL and the politeus muscle - The firm attachment of the arcuate ligament to the lateral meniscus and the attachment of the popliteus muscle to both the arcuate ligament and meniscus ensure the dynamic retraction of the posterior segment of the meniscus during internal rotation of the tibia on the femur as the knee begins to ‘unlock’
Medial meniscus - ACL, medial collateral ligament, - more likely to be injured due to it’s association with this medial collateral ligament (unhappy triad = damage to the ACL, medial collateral ligament, and the medial meniscus)
List the four major bursae around the knee joint - which ones communicate with the joint space?
Suprapatella bursa – This is an extension of the synovial cavity of the knee, located between the quadriceps femoris and the femur.- the only one that communicates with the knee joint?
Prepatella bursa
Infrapatella bursa
Semimembranosus bursa
What is Bursitis? What can cause it?
Bursitis is the swelling of any bursa
A sharp blow to the knee can cause symptoms to appear rapidly. But most cases of knee bursitis result from friction and irritation of the bursa that occurs in jobs that require a lot of kneeling on hard surfaces (maid’s knee)
What is a baker’s cyst?
A Baker’s cyst is caused when excess synovial fluid is pushed into one of the bursaes behind the knee. When this sac fills with fluid and bulges out, it is called a cyst. The excess fluid is usually caused by conditions such as rheumatoid arthritis or osteoarthritis that irritate the knee.
Find the popliteal, the posterior tibial and the dorsalis pedis pulse on yourself and on a friend- know where to find them on a surface model
how does the venous blood drain from the foot against gravity?
Venous valves prevent backflow of blood -
What is a varicose vein?
Varicose veins occur when there is pooling of blood in a vein and it expands due to the increased pressure - this often occurs in the legs due to weakening of the venous valves
What may cause an ulcer in the leg?
Venous ulcers - due to excessive pooling of blood, any sort of leakage of the vessels could cause degradation of the surrounding skin - causing a venous ulcer
Arterial ulcers- due to a lack of blood in the area, usually occur at pressure points in the foot. They are usually ‘punched out’ in appearance and occur due to damage to cells and lack of blood flow for healing
Diabetic nueropathy ulcers- due to insufficient sensation in the extremities, damage to the area goes undetected and therefore large ulcers could develop without the patient knowing. These often occur on the bottom of the feet and take a very long time to heal due to insufficient blood flow.
Why is a kick in the medial aspect of the leg so painful?
There is no muscle directly covering this area, therefore the force is directly impacting the bone.
Why do fractures of the tibia tend to heal slowly?
lack of blood supply - no direct muscle attachments on anterior tibia
What is Hilton’s Law?
The nerves which supply muscles that act on a joint, also supply the joint itself
What is a deep venous thrombosis?
a blood clot in a deep vein of the leg
Do the long and short saphenous veins communicate?
Yes, they do; at the level of the lower leg they freely anastomose.
Where does the short saphenous vein drain into?
the popliteal vein - close to the popliteal fossa
at what site is the common peroneal nerve in danger of injury from trauma? Describe the areas of sensory and motor loss following such an injury
The most common site for peroneal nerve damage is at the head of the fibula. Damage to the common peroneal nerve would lead to foot drop or an inability to dorsiflex one’s foot (anterior compartment leg muscles). Damage to this nerve would cause loss of feeling in the toes and the lateral leg
is the inferior tibiofibular joint easily dislocated?
no - there is a very strong interosseus ligament that connects the two together as well as an anterior and posterior tibiofibular ligaments.
Which nerves are responsible for the ankle jerk reflex? how many synapses are involved?
tibial nerve - Being a deep tendon reflex, it is monosynaptic.
What are the stabilizing factors of the knee?
ACL
PCL
Medial/Lateral collateral ligaments
‘locking mechanism’
popliteus muscle
Quadriceps tendon/patellofemoral ligament
