Week 5: Bursae & Muscles of the Knee Joint Flashcards
Describe the gross morphology of a bursa:
- A closed connective tissue sac (filled with fluid) which develops in response to friction
- Typically collapsed, containing only enough fluid to moisten their walls (i.e. a potential space)
What is bursitis?
When the space between the walls may become inflated with fluid if the bursa becomes inflamed
What is the function of a bursa?
Decreases friction between tendon and bone, ligament and bone, bone and skin, muscle and muscle, muscle and tendon, muscle and bone
Where is the prepatellar bursa located?
Between the skin and lower part of patella and the patellar ligament
Where is the superficial infrapatellar bursa located?
Between the skin and the patellar ligament i.e. it is subcutaneous
Where is the suprapatellar bursa or recess located?
Between the tendon of the quadriceps and the anterior surface of the femur
Where is the deep infrapatellar bursa located?
Between the patellar ligament and the tibia
Where are the bursae of the heads of gastrocnemius located?
Between the tendon of origin of each head and the joint capsule
What muscles cross anterior to the knee joint?
Quadriceps femoris:
- Rectus femoris
- Vastus medialis
- Vastus lateralis
- Vastus intermedius
Which muscles attach to the patella via the quadriceps tendon?
The four heads of the quadriceps femoris muscle
What is the action of the quadriceps muscles at the knee joint?
- Extension of the leg on the thigh
- Patellar stability - particularly vastus medialis
What is the innervation of the quadriceps muscles?
Femoral nerve
What muscles cross posterior to the knee joint?
- Hamstring muscles:
- Semitendinosus
- Semimembranosus
- Biceps femoris - Sartorius
- Gracilis
- Gastrocnemius
- Popliteus
What are the attachments sites of the semimembranosus?
- Ischial tuberosity
- Posteromedial aspect of tibia, medial condyle of tibia
What are the attachments sites of the semitendinosus?
- Ischial tuberosity
- Anteromedial aspect body of tibia medial and inferior to tibial tuberosity
What are the attachments sites of the biceps femoris?
- Long head: ischial tuberosity
- Short head: lateral lip linea aspera and lateral intermuscular septum
- Head of fibula and lateral tibial condyle
What are the attachments sites of the gastrocnemius?
- Medial and lateral femoral condyles
- Posterior surface calcaneus
What are the attachments sites of the popliteus?
- Lateral condyle of femur
- Posterior surface of tibia above soleal line
What is the plantaris?
A small muscle that attaches to the lateral femoral condyle deep to the lateral head of gastrocnemius also crosses the posterior knee joint
What nerve innervates each of the posterior muscles of the knee joint?
All innervated by the tibial nerve, except the short head of biceps femoris which is supplied by the common fibular nerve
Describe the general action of the posterior muscles of the knee joint:
Flexion of the leg
With the leg off the ground, what action of the tibia will popliteus perform?
Medially rotates the tibia (femur considered fixed)
If the foot was firmly planted on the ground, so that the tibia stayed fixed, what action of the femur would popliteus perform?
Laterally rotates femur during weight bearing, and stabilises the femur against any unwanted medial rotation (tibia considered fixed)
When the tibia is non-weightbearing, what muscle(s) are capable of producing medial rotation of the tibia?
Semitendinosus, gracilis, sartorius
Semimembranosus, popliteus
