knee joint and Popliteal Fossa Flashcards
What are the 4 primary flexors of the hip joint?
Psoas major
Psoas minor
Iliacus
Sartorius
What is the action of the psoas major, psoas minor, and iliacus?
Flexes and laterally rotates the hip joint together with the iliacus (as iliopsoas).
Stabilizes the hip joint.
What is the nerve supply of the psoas major and minor?
Direct branches from the lumbar plexus (L
What is the nerve supply of the iliacus?
Femoral nerve (L2-L4).
What is the action of the sartorius muscle?
Flexes, abducts, and laterally rotates the hip joint.
Flexes the knee.
Medially rotates a flexed knee.
What is the nerve supply of the sartorius muscle?
Femoral nerve (L2-L4).
What is the primary extensor of the knee joint?
Quadriceps femoris.
What muscles make up the quadriceps femoris?
Rectus femoris
Vastus lateralis
Vastus medialis
Vastus intermedius
What is the action of the rectus femoris?
Extends the knee joint.
Helps flex the hip joint.
Steadies the hip joint.
What is the action of the vastus lateralis, vastus medialis, and vastus intermedius?
Extend the knee joint.
What is the nerve supply of the rectus femoris, vastus lateralis, vastus medialis, vastus intermedius?
Femoral nerve (L2-L4).
What is the femoral triangle?
A triangular anatomical landmark important for dissections and understanding groin relationships.
what are the 4 borders of the femoral triangle?
Superiorly – Inguinal ligament
Laterally – Sartorius
Medially – Adductor longus
Floor – Iliopsoas (lateral), Pectineus and Adductor longus (medial)
What are the key contents of the femoral triangle?
Femoral nerve, artery, and vein
Deep inguinal lymph nodes
What is the clinical relevance of the femoral triangle?
Palpation of the femoral artery pulse.
Cannulation of the femoral artery (used in cardiac/coronary angiography).
Venous puncture of the femoral vein.
Site of femoral hernia.
Used in administration of embalming fluids.
What are the primary adductors of the hip joint?
Adductor longus
Adductor brevis
Adductor magnus
Gracilis
Obturator externus
Pectineus
What is the action of the adductor longus and brevis?
Adducts the hip joint.
What is the nerve supply of the adductor longus and brevis?
Obturator nerve (L2-L4).
What is the action of the adductor magnus?
Adducts the hip joint.
Adductor part: Flexes the hip joint.
Hamstring part: Extends the hip joint.
What is the nerve supply of the adductor magnus?
Adductor part: Obturator nerve (L2-L4).
Hamstring part: Tibial division of sciatic nerve.
What is the action of the gracilis muscle?
Adducts the hip joint.
Flexes and medially rotates the knee joint.
What is the nerve supply of the gracilis and obturator externus muscle?
Obturator nerve (L2-L4).
What is the action of the obturator externus?
Adducts and laterally rotates the hip joint; steadies the femoral head in the acetabulum.
What is the action of the pectineus muscle?
Adducts and slightly flexes the hip joint; assists in medial rotation.
What is the nerve supply of the pectineus muscle?
Femoral nerve (L2-L4), may also receive innervation from the obturator nerve.
What are the extensors of the hip joint and flexors of the knee joint?
Semitendinosus
Semimembranosus
Biceps femoris
what is the action of the semitendinosus and Semimembranosus?
Extends the hip joint.
Flexes the knee joint.
Medially rotates the knee when flexed.
What is the nerve supply of the semitendinosus and semimembranosus?
Tibial division of the sciatic nerve.
What is the action of the biceps femoris?
Flexes the knee joint.
Laterally rotates the knee when flexed.
Long head extends the hip joint.
What is the nerve supply of the biceps femoris?
Long head: Tibial division of the sciatic nerve.
Short head: Common fibular division of the sciatic nerve.
What type of joint is the knee joint?
It is a synovial hinge joint that allows flexion and extension, with gliding and rotation, making it a modified hinge joint.
is the fibula involved in the knee joint?
No, the fibula is not involved in the knee joint.
Why is the knee joint mechanically unstable?
Due to the incongruence of the articulating bones, making it function like two balls sitting on a warped tabletop.
What are the three main articulations of the knee joint?
Medial femorotibial joint
Lateral femorotibial joint
Patellofemoral joint
What provides stability to the knee joint?
Muscles and their tendons (most important for stability).
Ligaments connecting the femur and tibia.
What are the main movements of the knee joint?
Flexion and extension; some rotation occurs when the knee is flexed.
What happens when the knee is fully extended with the foot on the ground?
The knee passively locks due to medial rotation of the femoral condyles on the tibial plateau.
Why is the locked knee position important?
It makes the lower limb a solid column, improving weight-bearing stability.
How is the knee unlocked for flexion?
The popliteus muscle contracts, laterally rotating the femur by 5° on the tibial plateau.
What type of rotation occurs when the knee is flexed?
Medial rotation of the leg (when knee flexed 10-90°).
Lateral rotation of the leg (when knee flexed 30-40°).
Where are the cruciate ligaments located?
In the center of the knee joint, crossing each other obliquely.
What is the function of the cruciate ligaments
They connect the femur and tibia and limit excessive rotation.
how do the cruciate ligaments respond to medial rotation of the tibia on the femur?
They wind around each other, limiting medial rotation to about 10°.
how do the cruciate ligaments respond to lateral rotation of the tibia on the femur?
They unwind, allowing nearly 40° of lateral rotation when the knee is flexed to 90°.
What happens to the cruciate ligaments in different knee positions?
Due to their oblique orientation, at least one cruciate ligament is always tense in every position.
Where does the anterior cruciate ligament (ACL) arise from?
Anterior intercondylar area of the tibia.
Where does the ACL attach?
Posterior part of the medial side of the lateral condyle of the femur.
What is the function of the ACL?
Prevents posterior displacement of the femur on the tibia.
How does the ACL prevent tibial movement in flexion?
When the knee is flexed at a right angle, the tibia cannot be pulled anteriorly due to the ACL.
Where does the posterior cruciate ligament (PCL) arise from?
Posterior intercondylar area of the tibia.
Where does the PCL attach?
Anterior part of the lateral surface of the medial condyle of the femur.
What is the function of the PCL?
Prevents anterior displacement of the femur on the tibia.
which is ACL/ PCL attachment
What are the menisci of the knee joint?
Crescent-shaped fibrocartilage plates on the tibia that deepen the surface for better joint congruency and absorb shock.
How do the menisci appear in cross-section?
They are thicker at their external margins and taper to thin edges on the inner joint, forming a wedge shape.
How are the menisci attached to the tibia?
They are firmly attached at their ends to the intercondylar area of the tibia.
What are the differences between the medial and lateral menisci?
Medial meniscus: C-shaped, less mobile, attached to the tibial collateral ligament.
Lateral meniscus: Circular, smaller, and more freely movable.
What is the transverse ligament of the knee?
ligament that joins the anterior edges of the menisci.
What 3 muscles form the Pes Anserinus?
Sartorius, Gracilis, and Semitendinosus.
Where does the Pes Anserinus insert?
Superior part of the medial surface of the tibia.
Why is the Pes Anserinus unique?
It consists of three muscles from different thigh compartments, each innervated by different nerves but sharing a common tendinous insertion.
What is the functional significance of the Pes Anserinus?
It contributes to medial knee stability, similar to how the gluteus maximus and tensor fasciae latae stabilize the lateral knee via the iliotibial tract.
What is the most common knee injury in contact sports?
Ligament sprain, often occurring when the foot is fixed on the ground and a force is applied against the knee.
Why is the attachment of the Tibial Collateral Ligament (TCL) to the medial meniscus clinically significant?
Because tearing of the TCL often results in concomitant tearing of the medial meniscus.
What are common causes of TCL and medial meniscus injuries?
A blow to the lateral side of an extended knee
Excessive lateral twisting of the flexed knee
What is the Unhappy Triad of knee injuries?
Tibial Collateral Ligament (TCL)
Medial meniscus
Anterior Cruciate Ligament (ACL)
^ This occurs when the ACL, which serves as a pivot for knee rotation, is torn along with the other two structures.
What type of force can tear the Anterior Cruciate Ligament (ACL)?
Hyperextension and severe force directed anteriorly against the femur when the knee is semiflexed.
what is the anterior drawer sign, and what does it indicate?
The free tibia slides anteriorly under the fixed femur, indicating an ACL rupture.
What is the function of the ACL in knee stability?
The ACL prevents posterior displacement of the femur on the tibia and also prevents hyperextension of the knee.
What is the posterior drawer sign, and what does it indicate?
The free tibia slides posteriorly under the fixed femur, indicating a PCL rupture.
What is the popliteal fossa, and where is it located?
fat-filled compartment on the posterior aspect of the knee joint.
What are the superior borders of the popliteal fossa?
Superolaterally: Biceps femoris
Superomedially: Semimembranosus
What are the inferior borders of the popliteal fossa?
Inferolaterally: Lateral head of gastrocnemius
Inferomedially: Medial head of gastrocnemius
What structures form the roof and floor of the popliteal fossa?
Roof: Skin and popliteal fascia
Floor: Knee joint capsule, distal femur, proximal tibia, and popliteus muscle
What are the nerve contents of the popliteal fossa?
Tibial nerve
Common fibular nerve
Posterior cutaneous nerve of the thigh
What are the vessels found in the popliteal fossa?
Popliteal artery and vein (including their branches and tributaries)
Small saphenous vein
What type of lymph nodes are present in the popliteal fossa?
Popliteal lymph nodes
